Use predefined variables

Azure DevOps Services | Azure DevOps Server 2022 - Azure DevOps Server 2019

Variables give you a convenient way to get key bits of data into various parts of your pipeline. This is a list of predefined variables that are available for your use. There may be a few other predefined variables, but they're mostly for internal use.

These variables are automatically set by the system and read-only. (The exceptions are Build.Clean and System.Debug.)

In YAML pipelines, you can reference predefined variables as environment variables. For example, the variable Build.ArtifactStagingDirectory becomes the variable BUILD_ARTIFACTSTAGINGDIRECTORY.

For classic pipelines, you can use release variables in your deploy tasks to share the common information (for example, Environment Name, Resource Group, etc.).

Learn more about working with variables.

Build.Clean

This is a deprecated variable that modifies how the build agent cleans up source. To learn how to clean up source, see Clean the local repo on the agent.

System.AccessToken

System.AccessToken is a special variable that carries the security token used by the running build.

In YAML, you must explicitly map System.AccessToken into the pipeline using a variable. You can do this at the step or task level:

steps:
  - script: |
      echo "Using System.AccessToken to authenticate"
      git clone https://$(System.AccessToken)@dev.azure.com/yourorganization/yourproject/_git/yourrepository
    displayName: 'Clone repository using System.AccessToken'
    env:
      SYSTEM_ACCESSTOKEN: $(System.AccessToken)

You can configure the default scope for System.AccessToken using build job authorization scope.

System.Debug

For more detailed logs to debug pipeline problems, define System.Debug and set it to true.

  1. Edit your pipeline.

  2. Select Variables.

  3. Add a new variable with the name System.Debug and value true.

    Set System Debug to true

  4. Save the new variable.

Setting System.Debug to true configures verbose logs for all runs. You can also configure verbose logs for a single run with the Enable system diagnostics checkbox.

You can also set System.Debug to true as a variable in a pipeline or template.

variables:
  system.debug: 'true'

When System.Debug is set to true, an extra variable named Agent.Diagnostic is set to true. When Agent.Diagnostic is true, the agent collects more logs that can be used for troubleshooting network issues for self-hosted agents. For more information, see Network diagnostics for self-hosted agents.

Note

The Agent.Diagnostic variable is available with Agent v2.200.0 and higher.

For more information, see Review logs to diagnose pipeline issues.

Agent variables (DevOps Services)

Note

You can use agent variables as environment variables in your scripts and as parameters in your build tasks. You cannot use them to customize the build number or to apply a version control label or tag.

Variable Description
Agent.BuildDirectory The local path on the agent where all folders for a given build pipeline are created. This variable has the same value as Pipeline.Workspace. For example: /home/vsts/work/1.
Agent.ContainerMapping A mapping from container resource names in YAML to their Docker IDs at runtime.

Example follows table.
Agent.HomeDirectory The directory the agent is installed into. This contains the agent software. For example: c:\agent.
Agent.Id The ID of the agent.
Agent.JobName The name of the running job. This will usually be "Job"; or "__default", but in multi-config scenarios, will be the configuration.
Agent.JobStatus The status of the build.
  • Canceled
  • Failed
  • Succeeded
  • SucceededWithIssues (partially successful)
  • Skipped (last job)
The environment variable should be referenced as AGENT_JOBSTATUS. The older agent.jobstatus is available for backwards compatibility.
Agent.MachineName The name of the machine on which the agent is installed.
Agent.Name The name of the agent that is registered with the pool.

If you're using a self-hosted agent, then this name is specified by you. See agents.
Agent.OS The operating system of the agent host. Valid values are:
  • Windows_NT
  • Darwin
  • Linux
If you're running in a container, the agent host and container may be running different operating systems.
Agent.OSArchitecture The operating system processor architecture of the agent host. Valid values are:
  • X86
  • X64
  • ARM
Agent.TempDirectory A temporary folder that is cleaned after each pipeline job. This directory is used by tasks such as .NET Core CLI task to hold temporary items like test results before they're published.

For example: /home/vsts/work/_temp for Ubuntu.
Agent.ToolsDirectory The directory used by tasks such as Node Tool Installer and Use Python Version to switch between multiple versions of a tool.

These tasks add tools from this directory to PATH so that subsequent build steps can use them.

Learn about managing this directory on a self-hosted agent.
Agent.WorkFolder The working directory for this agent.

For example: c:\agent_work.

Note: This directory isn't guaranteed to be writable by pipeline tasks (for example, when mapped into a container)

Example of Agent.ContainerMapping:

{
  "one_container": {
    "id": "bdbb357d73a0bd3550a1a5b778b62a4c88ed2051c7802a0659f1ff6e76910190"
  },
  "another_container": {
    "id": "82652975109ec494876a8ccbb875459c945982952e0a72ad74c91216707162bb"
  }
}

Build variables (DevOps Services)

When you use a variable in a template that is not marked as available in templates, the variable will not render. The variable won't render because its value is not accessible within the template's scope.

Variable Description Available in templates?
Build.ArtifactStagingDirectory The local path on the agent where any artifacts are copied to before being pushed to their destination. For example: c:\agent_work\1\a.

A typical way to use this folder is to publish your build artifacts with the Copy files and Publish build artifacts tasks.

Note: Build.ArtifactStagingDirectory and Build.StagingDirectory are interchangeable. This directory is purged before each new build, so you don't have to clean it up yourself.

See Artifacts in Azure Pipelines.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.BuildId The ID of the record for the completed build. No
Build.BuildNumber The name of the completed build, also known as the run number. You can specify what is included in this value.

A typical use of this variable is to make it part of the label format, which you specify on the repository tab.

Note: This value can contain whitespace or other invalid label characters. In these cases, the label format fails.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.BuildUri The URI for the build. For example: vstfs:///Build/Build/1430.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.BinariesDirectory The local path on the agent you can use as an output folder for compiled binaries.

By default, new build pipelines aren't set up to clean this directory. You can define your build to clean it up on the Repository tab.

For example: c:\agent_work\1\b.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.ContainerId The ID of the container for your artifact. When you upload an artifact in your pipeline, it's added to a container that is specific for that particular artifact. No
Build.CronSchedule.DisplayName The displayName of the cron schedule that triggered the pipeline run. This variable is only set if the pipeline run is triggered by a YAML scheduled trigger. For more information, see schedules.cron definition - Build.CronSchedule.DisplayName variable Yes
Build.DefinitionName The name of the build pipeline.

Note: This value can contain whitespace or other invalid label characters. In these cases, the label format fails.
Yes
Build.DefinitionVersion The version of the build pipeline. Yes
Build.QueuedBy See "How are the identity variables set?".

Note: This value can contain whitespace or other invalid label characters. In these cases, the label format fails.
Yes
Build.QueuedById See "How are the identity variables set?". Yes
Build.Reason The event that caused the build to run.
  • Manual: A user manually queued the build.
  • IndividualCI: Continuous integration (CI) triggered by a Git push or a TFVC check-in.
  • BatchedCI: Continuous integration (CI) triggered by a Git push or a TFVC check-in, and the Batch changes was selected.
  • Schedule: Scheduled trigger.
  • ValidateShelveset: A user manually queued the build of a specific TFVC shelveset.
  • CheckInShelveset: Gated check-in trigger.
  • PullRequest: The build was triggered by a Git branch policy that requires a build.
  • BuildCompletion: The build was triggered by another build
  • ResourceTrigger: The build was triggered by a resource trigger or it was triggered by another build.
See Build pipeline triggers, Improve code quality with branch policies.
Yes
Build.Repository.Clean The value you've selected for Clean in the source repository settings.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.LocalPath The local path on the agent where your source code files are downloaded. For example: c:\agent_work\1\s.

By default, new build pipelines update only the changed files. You can modify how files are downloaded on the Repository tab.

Important note: If you check out only one Git repository, this path is the exact path to the code.

If you check out multiple repositories, the behavior is as follows (and might differ from the value of the Build.SourcesDirectory variable):
  • If the checkout step for the self (primary) repository has no custom checkout path defined, or the checkout path is the multi-checkout default path $(Pipeline.Workspace)/s/&<RepoName> for the self repository, the value of this variable reverts to its default value, which is $(Pipeline.Workspace)/s.
  • If the checkout step for the self (primary) repository does have a custom checkout path defined (and it's not its multi-checkout default path), this variable contains the exact path to the self repository.
This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.ID The unique identifier of the repository.

This won't change, even if the name of the repository does.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.Name The name of the triggering repository.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.Provider The type of the triggering repository.
This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.Tfvc.Workspace Defined if your repository is Team Foundation Version Control. The name of the TFVC workspace used by the build agent.

For example, if the Agent.BuildDirectory is c:\agent_work\12 and the Agent.Id is 8, the workspace name could be: ws_12_8

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.Uri The URL for the triggering repository. For example:
This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.RequestedFor See "How are the identity variables set?".

Note: This value can contain whitespace or other invalid label characters. In these cases, the label format fails.
Yes
Build.RequestedForEmail See "How are the identity variables set?". Yes
Build.RequestedForId See "How are the identity variables set?". Yes
Build.SourceBranch The branch of the triggering repo the build was queued for. Some examples:
  • Git repo branch: refs/heads/main
  • Git repo pull request: refs/pull/1/merge
  • TFVC repo branch: $/teamproject/main
  • TFVC repo gated check-in: Gated_2016-06-06_05.20.51.4369;username@live.com
  • TFVC repo shelveset build: myshelveset;username@live.com
  • When your pipeline is triggered by a tag: refs/tags/your-tag-name
When you use this variable in your build number format, the forward slash characters (/) are replaced with underscore characters _).

Note: In TFVC, if you're running a gated check-in build or manually building a shelveset, you can't use this variable in your build number format.
Yes
Build.SourceBranchName The name of the branch in the triggering repo the build was queued for.
  • Git repo branch, pull request, or tag: The last path segment in the ref. For example, in refs/heads/main this value is main. In refs/heads/feature/tools this value is tools. In refs/tags/your-tag-name this value is your-tag-name.
  • TFVC repo branch: The last path segment in the root server path for the workspace. For example, in $/teamproject/main this value is main.
  • TFVC repo gated check-in or shelveset build is the name of the shelveset. For example, Gated_2016-06-06_05.20.51.4369;username@live.com or myshelveset;username@live.com.
Note: In TFVC, if you're running a gated check-in build or manually building a shelveset, you can't use this variable in your build number format.
Yes
Build.SourcesDirectory The local path on the agent where your source code files are downloaded. For example: c:\agent_work\1\s.

By default, new build pipelines update only the changed files.

Important note: If you check out only one Git repository, this path is the exact path to the code. If you check out multiple repositories, it reverts to its default value, which is $(Pipeline.Workspace)/s, even if the self (primary) repository is checked out to a custom path different from its multi-checkout default path $(Pipeline.Workspace)/s/<RepoName> (in this respect, the variable differs from the behavior of the Build.Repository.LocalPath variable).

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.SourceVersion The latest version control change of the triggering repo that is included in this build.
This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Yes
Build.SourceVersionMessage The comment of the commit or changeset for the triggering repo. We truncate the message to the first line or 200 characters, whichever is shorter.

The Build.SourceVersionMessage corresponds to the message on Build.SourceVersion commit. The Build.SourceVersion commit for a PR build is the merge commit (not the commit on the source branch).

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.

Also, this variable is only available on the step level and is not available in the job or stage levels (that is, the message isn't extracted until the job starts and the code is checked out).

Note: This variable is available in TFS 2015.4.

Note: The Build.SourceVersionMessage variable does not work with classic build pipelines in Bitbucket repositories when Batch changes while a build is in progress is enabled.
No
Build.StagingDirectory The local path on the agent where any artifacts are copied to before being pushed to their destination. For example: c:\agent_work\1\a.

A typical way to use this folder is to publish your build artifacts with the Copy files and Publish build artifacts tasks.

Note: Build.ArtifactStagingDirectory and Build.StagingDirectory are interchangeable. This directory is purged before each new build, so you don't have to clean it up yourself.

See Artifacts in Azure Pipelines.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.Git.SubmoduleCheckout The value you've selected for Checkout submodules on the repository tab. With multiple repos checked out, this value tracks the triggering repository's setting.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.SourceTfvcShelveset Defined if your repository is Team Foundation Version Control.

If you're running a gated build or a shelveset build, this is set to the name of the shelveset you're building.

Note: This variable yields a value that is invalid for build use in a build number format.
No
Build.TriggeredBy.BuildId If the build was triggered by another build, then this variable is set to the BuildID of the triggering build. In Classic pipelines, this variable is triggered by a build completion trigger.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.

If you're triggering a YAML pipeline using resources, you should use the resources variables instead.
No
Build.TriggeredBy.DefinitionId If the build was triggered by another build, then this variable is set to the DefinitionID of the triggering build. In Classic pipelines, this variable is triggered by a build completion trigger.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.

If you're triggering a YAML pipeline using resources, you should use the resources variables instead.
No
Build.TriggeredBy.DefinitionName If the build was triggered by another build, then this variable is set to the name of the triggering build pipeline. In Classic pipelines, this variable is triggered by a build completion trigger.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.

If you're triggering a YAML pipeline using resources, you should use the resources variables instead.
No
Build.TriggeredBy.BuildNumber If the build was triggered by another build, then this variable is set to the number of the triggering build. In Classic pipelines, this variable is triggered by a build completion trigger.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.

If you're triggering a YAML pipeline using resources, you should use the resources variables instead.
No
Build.TriggeredBy.ProjectID If the build was triggered by another build, then this variable is set to ID of the project that contains the triggering build. In Classic pipelines, this variable is triggered by a build completion trigger.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.

If you're triggering a YAML pipeline using resources, you should use the resources variables instead.
No
Common.TestResultsDirectory The local path on the agent where the test results are created. For example: c:\agent_work\1\TestResults.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No

Pipeline variables (DevOps Services)

Variable Description
Pipeline.Workspace Workspace directory for a particular pipeline. This variable has the same value as Agent.BuildDirectory. For example, /home/vsts/work/1.

Tip

If you are using classic release pipelines, you can use classic releases and artifacts variables to store and access data throughout your pipeline.

Deployment job variables (DevOps Services)

These variables are scoped to a specific Deployment job and will be resolved only at job execution time.

Variable Description
Environment.Name Name of the environment targeted in the deployment job to run the deployment steps and record the deployment history. For example, smarthotel-dev.
Environment.Id ID of the environment targeted in the deployment job. For example, 10.
Environment.ResourceName Name of the specific resource within the environment targeted in the deployment job to run the deployment steps and record the deployment history. For example, bookings which is a Kubernetes namespace that has been added as a resource to the environment smarthotel-dev.
Environment.ResourceId ID of the specific resource within the environment targeted in the deployment job to run the deployment steps. For example, 4.
Strategy.Name The name of the deployment strategy: canary, runOnce, or rolling.
Strategy.CycleName The current cycle name in a deployment. Options are PreIteration, Iteration, or PostIteration.

System variables (DevOps Services)

When you use a variable in a template that is not marked as available in templates, the variable will not render. The variable won't render because its value is not accessible within the template's scope.

Variable Description Available in templates?
System.AccessToken Use the OAuth token to access the REST API.

Use System.AccessToken from YAML scripts.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Yes
System.CollectionId The GUID of the TFS collection or Azure DevOps organization. Yes
System.CollectionUri The URI of the TFS collection or Azure DevOps organization. For example: https://dev.azure.com/fabrikamfiber/. Yes
System.DefaultWorkingDirectory The local path on the agent where your source code files are downloaded. For example: c:\agent_work\1\s

By default, new build pipelines update only the changed files. You can modify how files are downloaded on the Repository tab.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Yes
System.DefinitionId The ID of the build pipeline. Yes
System.HostType Set to build if the pipeline is a build. For a release, the values are deployment for a Deployment group job, gates during evaluation of gates, and release for other (Agent and Agentless) jobs. Yes
System.JobAttempt Set to 1 the first time this job is attempted, and increments every time the job is retried. No
System.JobDisplayName The human-readable name given to a job. No
System.JobId A unique identifier for a single attempt of a single job. The value is unique to the current pipeline. No
System.JobName The name of the job, typically used for expressing dependencies and accessing output variables. No
System.OidcRequestUri Generate an idToken for authentication with Entra ID using OpenID Connect (OIDC). Learn more. Yes
System.PhaseAttempt Set to 1 the first time this phase is attempted, and increments every time the job is retried.

Note: "Phase" is a mostly redundant concept, which represents the design-time for a job (whereas job was the runtime version of a phase). We've mostly removed the concept of "phase" from Azure Pipelines. Matrix and multi-config jobs are the only place where "phase" is still distinct from "job." One phase can instantiate multiple jobs, which differ only in their inputs.
No
System.PhaseDisplayName The human-readable name given to a phase. No
System.PhaseName A string-based identifier for a job, typically used for expressing dependencies and accessing output variables. No
System.PlanId A string-based identifier for a single pipeline run. No
System.PullRequest.IsFork If the pull request is from a fork of the repository, this variable is set to True.

Otherwise, it's set to False.
Yes
System.PullRequest.PullRequestId The ID of the pull request that caused this build. For example: 17. (This variable is initialized only if the build ran because of a Git PR affected by a branch policy). No
System.PullRequest.PullRequestNumber The number of the pull request that caused this build. This variable is populated for pull requests from GitHub that have a different pull request ID and pull request number. This variable is only available in a YAML pipeline if the PR is affected by a branch policy. No
System.PullRequest.targetBranchName The name of the target branch for a pull request. This variable can be used in a pipeline to conditionally execute tasks or steps based on the target branch of the pull request. For example, you might want to trigger a different set of tests or code analysis tools depending on the branch that the changes are being merged into. No
System.PullRequest.SourceBranch The branch that is being reviewed in a pull request. For example: refs/heads/users/raisa/new-feature for Azure Repos. (This variable is initialized only if the build ran because of a Git PR affected by a branch policy). This variable is only available in a YAML pipeline if the PR is affected by a branch policy. No
System.PullRequest.SourceCommitId The commit that is being reviewed in a pull request. (This variable is initialized only if the build ran because of a Git PR affected by a branch policy). This variable is only available in a YAML pipeline if the PR is affected by a branch policy.
System.PullRequest.SourceRepositoryURI The URL to the repo that contains the pull request. For example: https://dev.azure.com/ouraccount/_git/OurProject. No
System.PullRequest.TargetBranch The branch that is the target of a pull request. For example: refs/heads/main when your repository is in Azure Repos and main when your repository is in GitHub. This variable is initialized only if the build ran because of a Git PR affected by a branch policy. This variable is only available in a YAML pipeline if the PR is affected by a branch policy. No
System.StageAttempt Set to 1 the first time this stage is attempted, and increments every time the job is retried. No
System.StageDisplayName The human-readable name given to a stage. No
System.StageName A string-based identifier for a stage, typically used for expressing dependencies and accessing output variables. No
System.TeamFoundationCollectionUri The URI of the TFS collection or Azure DevOps organization. For example: https://dev.azure.com/fabrikamfiber/.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Yes
System.TeamProject The name of the project that contains this build. Yes
System.TeamProjectId The ID of the project that this build belongs to. Yes
System.TimelineId A string-based identifier for the execution details and logs of a single pipeline run. No
TF_BUILD Set to True if the script is being run by a build task.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No

Checks variables (DevOps Services)

Variable Description
Checks.StageAttempt Set to 1 the first time this stage is attempted, and increments every time the stage is retried.

This variable can only be used within an approval or check for an environment. For example, you could use $(Checks.StageAttempt) within an Invoke REST API check.

Add the stage attempt as a parameter.

Agent variables (DevOps Server 2022)

Note

You can use agent variables as environment variables in your scripts and as parameters in your build tasks. You cannot use them to customize the build number or to apply a version control label or tag.

Variable Description
Agent.BuildDirectory The local path on the agent where all folders for a given build pipeline are created. This variable has the same value as Pipeline.Workspace. For example: /home/vsts/work/1.
Agent.ContainerMapping A mapping from container resource names in YAML to their Docker IDs at runtime. Example follows table.
Agent.HomeDirectory The directory the agent is installed into. This contains the agent software. For example: c:\agent.
Agent.Id The ID of the agent.
Agent.JobName The name of the running job. This will usually be "Job" or "__default", but in multi-config scenarios, will be the configuration.
Agent.JobStatus The status of the build.
  • Canceled
  • Failed
  • Succeeded
  • SucceededWithIssues (partially successful)
  • Skipped (last job)
The environment variable should be referenced as AGENT_JOBSTATUS. The older agent.jobstatus is available for backwards compatibility.
Agent.MachineName The name of the machine on which the agent is installed.
Agent.Name The name of the agent that is registered with the pool.

If you're using a self-hosted agent, then this name is specified by you. See agents.
Agent.OS The operating system of the agent host. Valid values are:
  • Windows_NT
  • Darwin
  • Linux
If you're running in a container, the agent host and container might be running different operating systems.
Agent.OSArchitecture The operating system processor architecture of the agent host. Valid values are:
  • X86
  • X64
  • ARM
Agent.TempDirectory A temporary folder that is cleaned after each pipeline job. This directory is used by tasks such as .NET Core CLI task to hold temporary items like test results before they're published.

For example: /home/vsts/work/_temp for Ubuntu.
Agent.ToolsDirectory The directory used by tasks such as Node Tool Installer and Use Python Version to switch between multiple versions of a tool.

These tasks add tools from this directory to PATH so that subsequent build steps can use them.

Learn about managing this directory on a self-hosted agent.
Agent.WorkFolder The working directory for this agent. For example: c:\agent_work.

Note: This directory isn't guaranteed to be writable by pipeline tasks (for example, when mapped into a container).

Example of Agent.ContainerMapping:

{
  "one_container": {
    "id": "bdbb357d73a0bd3550a1a5b778b62a4c88ed2051c7802a0659f1ff6e76910190"
  },
  "another_container": {
    "id": "82652975109ec494876a8ccbb875459c945982952e0a72ad74c91216707162bb"
  }
}

Build variables (DevOps Server 2022)

When you use a variable in a template that is not marked as available in templates, the variable will not render. The variable won't render because its value is not accessible within the template's scope.

Variable Description Available in templates?
Build.ArtifactStagingDirectory The local path on the agent where any artifacts are copied to before being pushed to their destination. For example: c:\agent_work\1\a.

A typical way to use this folder is to publish your build artifacts with the Copy files and Publish build artifacts tasks.

Note: Build.ArtifactStagingDirectory and Build.StagingDirectory are interchangeable. This directory is purged before each new build, so you don't have to clean it up yourself.

See Artifacts in Azure Pipelines.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.BuildId The ID of the record for the completed build. No
Build.BuildNumber The name of the completed build, also known as the run number. You can specify what is included in this value.

A typical use of this variable is to make it part of the label format, which you specify on the repository tab.

Note: This value can contain whitespace or other invalid label characters. In these cases, the label format fails.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.BuildUri The URI for the build. For example: vstfs:///Build/Build/1430.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.BinariesDirectory The local path on the agent you can use as an output folder for compiled binaries.

By default, new build pipelines aren't set up to clean this directory. You can define your build to clean it up on the Repository tab.

For example: c:\agent_work\1\b.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.ContainerId The ID of the container for your artifact. When you upload an artifact in your pipeline, it's added to a container that is specific for that particular artifact. No
Build.CronSchedule.DisplayName The displayName of the cron schedule that triggered the pipeline run. This variable is only set if the pipeline run is triggered by a YAML scheduled trigger. For more information, see schedules.cron definition - Build.CronSchedule.DisplayName variable. This variable is available in Azure DevOps Server 2022.1 and higher. Yes
Build.DefinitionName The name of the build pipeline.

Note: This value can contain whitespace or other invalid label characters. In these cases, the label format fails.
Yes
Build.DefinitionVersion The version of the build pipeline. Yes
Build.QueuedBy See "How are the identity variables set?".

Note: This value can contain whitespace or other invalid label characters. In these cases, the label format fails.
Yes
Build.QueuedById See "How are the identity variables set?. Yes
Build.Reason The event that caused the build to run.
  • Manual: A user manually queued the build.
  • IndividualCI: Continuous integration (CI) triggered by a Git push or a TFVC check-in.
  • BatchedCI: Continuous integration (CI) triggered by a Git push or a TFVC check-in, and the Batch changes was selected.
  • Schedule: Scheduled trigger.
  • ValidateShelveset: A user manually queued the build of a specific TFVC shelveset.
  • CheckInShelveset: Gated check-in trigger.
  • PullRequest: The build was triggered by a Git branch policy that requires a build.
  • BuildCompletion: The build was triggered by another build
  • ResourceTrigger: The build was triggered by a resource trigger or it was triggered by another build.
See Build pipeline triggers, Improve code quality with branch policies.
Yes
Build.Repository.Clean The value you've selected for Clean in the source repository settings.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.LocalPath The local path on the agent where your source code files are downloaded. For example: c:\agent_work\1\s.

By default, new build pipelines update only the changed files. You can modify how files are downloaded on the Repository tab.

Important note: If you check out only one Git repository, this path is the exact path to the code. If you check out multiple repositories, the behavior is as follows (and might differ from the value of the Build.SourcesDirectory variable):
  • If the checkout step for the self (primary) repository has no custom checkout path defined, or the checkout path is the multi-checkout default path $(Pipeline.Workspace)/s/<RepoName> for the self repository, the value of this variable reverts to its default value, which is $(Pipeline.Workspace)/s.
  • If the checkout step for the self (primary) repository does have a custom checkout path defined (and it's not its multi-checkout default path), this variable contains the exact path to the self repository.
This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.ID The unique identifier of the repository.

This won't change, even if the name of the repository does.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.Name The name of the triggering repository.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.Provider The type of the triggering repository.
This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.Tfvc.Workspace Defined if your repository is Team Foundation Version Control. The name of the TFVC workspace used by the build agent.

For example, if the Agent.BuildDirectory is c:\agent_work\12 and the Agent.Id is 8, the workspace name could be: ws_12_8.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.Uri The URL for the triggering repository. For example:This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag. No
Build.RequestedFor See "How are the identity variables set?".

Note: This value can contain whitespace or other invalid label characters. In these cases, the label format fails.
Yes
Build.RequestedForEmail See "How are the identity variables set?". Yes
Build.RequestedForId See "How are the identity variables set?". Yes
Build.SourceBranch The branch of the triggering repo the build was queued for. Some examples:
  • Git repo branch: refs/heads/main
  • Git repo pull request: refs/pull/1/merge
  • TFVC repo branch: $/teamproject/main
  • TFVC repo gated check-in: Gated_2016-06-06_05.20.51.4369;username@live.com
  • TFVC repo shelveset build: myshelveset;username@live.com
  • When your pipeline is triggered by a tag: refs/tags/your-tag-name
When you use this variable in your build number format, the forward slash characters (/) are replaced with underscore characters _).

Note: In TFVC, if you're running a gated check-in build or manually building a shelveset, you can't use this variable in your build number format.
Yes
Build.SourceBranchName The name of the branch in the triggering repo the build was queued for.
  • Git repo branch, pull request, or tag: The last path segment in the ref. For example, in refs/heads/main this value is main. In refs/heads/feature/tools this value is tools. In refs/tags/your-tag-name this value is your-tag-name.
  • TFVC repo branch: The last path segment in the root server path for the workspace. For example, in $/teamproject/main this value is main.
  • TFVC repo gated check-in or shelveset build is the name of the shelveset. For example, Gated_2016-06-06_05.20.51.4369;username@live.com or myshelveset;username@live.com.
Note: In TFVC, if you're running a gated check-in build or manually building a shelveset, you can't use this variable in your build number format.
Yes
Build.SourcesDirectory The local path on the agent where your source code files are downloaded. For example: c:\agent_work\1\s.

By default, new build pipelines update only the changed files.

Important note: If you check out only one Git repository, this path is the exact path to the code. If you check out multiple repositories, it reverts to its default value, which is $(Pipeline.Workspace)/s, even if the self (primary) repository is checked out to a custom path different from its multi-checkout default path $(Pipeline.Workspace)/s/<RepoName> (in this respect, the variable differs from the behavior of the Build.Repository.LocalPath variable).

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.SourceVersion The latest version control change of the triggering repo that is included in this build.
This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Yes
Build.SourceVersionMessage The comment of the commit or changeset for the triggering repo. We truncate the message to the first line or 200 characters, whichever is shorter.

The Build.SourceVersionMessage corresponds to the message on Build.SourceVersion commit. The Build.SourceVersion commit for a PR build is the merge commit (not the commit on the source branch).

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.

Also, this variable is only available on the step level and is not available in the job or stage levels (that is, the message isn't extracted until the job starts and the code is checked out).

Note: This variable is available in TFS 2015.4.

Note: The Build.SourceVersionMessage variable does not work with classic build pipelines in Bitbucket repositories when Batch changes while a build is in progress is enabled.
No
Build.StagingDirectory The local path on the agent where any artifacts are copied to before being pushed to their destination. For example: c:\agent_work\1\a.

A typical way to use this folder is to publish your build artifacts with the Copy files and Publish build artifacts tasks.

Note: Build.ArtifactStagingDirectory and Build.StagingDirectory are interchangeable. This directory is purged before each new build, so you don't have to clean it up yourself.

See Artifacts in Azure Pipelines.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.Git.SubmoduleCheckout The value you've selected for Checkout submodules on the repository tab. With multiple repos checked out, this value tracks the triggering repository's setting.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.SourceTfvcShelveset Defined if your repository is Team Foundation Version Control.

If you're running a gated build or a shelveset build, this is set to the name of the shelveset you're building.

Note: This variable yields a value that is invalid for build use in a build number format.
No
Build.TriggeredBy.BuildId If the build was triggered by another build, then this variable is set to the BuildID of the triggering build. In Classic pipelines, this variable is triggered by a build completion trigger.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.

If you're triggering a YAML pipeline using resources, you should use the resources variables instead.
No
Build.TriggeredBy.DefinitionId If the build was triggered by another build, then this variable is set to the DefinitionID of the triggering build. In Classic pipelines, this variable is triggered by a build completion trigger.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.

If you're triggering a YAML pipeline using resources, you should use the resources variables instead.
No
Build.TriggeredBy.DefinitionName If the build was triggered by another build, then this variable is set to the name of the triggering build pipeline. In Classic pipelines, this variable is triggered by a build completion trigger.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.

If you're triggering a YAML pipeline using resources, you should use the resources variables instead.
No
Build.TriggeredBy.BuildNumber If the build was triggered by another build, then this variable is set to the number of the triggering build. In Classic pipelines, this variable is triggered by a build completion trigger.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.

If you're triggering a YAML pipeline using resources, you should use the resources variables instead.
No
Build.TriggeredBy.ProjectID If the build was triggered by another build, then this variable is set to ID of the project that contains the triggering build. In Classic pipelines, this variable is triggered by a build completion trigger.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.

If you're triggering a YAML pipeline using resources, you should use the resources variables instead.
No
Common.TestResultsDirectory The local path on the agent where the test results are created. For example: c:\agent_work\1\TestResults.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No

Pipeline variables (DevOps Server 2022)

Variable Description
Pipeline.Workspace Workspace directory for a particular pipeline. This variable has the same value as Agent.BuildDirectory. For example, /home/vsts/work/1.

Tip

If you are using classic release pipelines, you can use classic releases and artifacts variables to store and access data throughout your pipeline.

Deployment job variables (DevOps Server 2022)

These variables are scoped to a specific Deployment job and will be resolved only at job execution time.

Variable Description
Environment.Name Name of the environment targeted in the deployment job to run the deployment steps and record the deployment history. For example, smarthotel-dev.
Environment.Id ID of the environment targeted in the deployment job. For example, 10.
Environment.ResourceName Name of the specific resource within the environment targeted in the deployment job to run the deployment steps and record the deployment history. For example, bookings which is a Kubernetes namespace that has been added as a resource to the environment smarthotel-dev.
Environment.ResourceId ID of the specific resource within the environment targeted in the deployment job to run the deployment steps. For example, 4.
Strategy.Name The name of the deployment strategy: canary, runOnce, or rolling.
Strategy.CycleName The current cycle name in a deployment. Options are PreIteration, Iteration, or PostIteration.

System variables (DevOps Server 2022)

When you use a variable in a template that is not marked as available in templates, the variable will not render. The variable won't render because its value is not accessible within the template's scope.

Variable Description Available in templates?
System.AccessToken Use the OAuth token to access the REST API.

Use System.AccessToken from YAML scripts.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Yes
System.CollectionId The GUID of the TFS collection or Azure DevOps organization. Yes
System.CollectionUri The URI of the TFS collection or Azure DevOps organization. For example: https://dev.azure.com/fabrikamfiber/. Yes
System.DefaultWorkingDirectory The local path on the agent where your source code files are downloaded. For example: c:\agent_work\1\s

By default, new build pipelines update only the changed files. You can modify how files are downloaded on the Repository tab.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Yes
System.DefinitionId The ID of the build pipeline. Yes
System.HostType Set to build if the pipeline is a build. For a release, the values are deployment for a Deployment group job, gates during evaluation of gates, and release for other (Agent and Agentless) jobs. Yes
System.JobAttempt Set to 1 the first time this job is attempted, and increments every time the job is retried. No
System.JobDisplayName The human-readable name given to a job. No
System.JobId A unique identifier for a single attempt of a single job. The value is unique to the current pipeline. No
System.JobName The name of the job, typically used for expressing dependencies and accessing output variables. No
System.PhaseAttempt Set to 1 the first time this phase is attempted, and increments every time the job is retried.

Note: "Phase" is a mostly redundant concept, which represents the design-time for a job (whereas job was the runtime version of a phase). We've mostly removed the concept of "phase" from Azure Pipelines. Matrix and multi-config jobs are the only place where "phase" is still distinct from "job." One phase can instantiate multiple jobs, which differ only in their inputs.
No
System.PhaseDisplayName The human-readable name given to a phase. No
System.PhaseName A string-based identifier for a job, typically used for expressing dependencies and accessing output variables. No
System.PlanId A string-based identifier for a single pipeline run. No
System.PullRequest.IsFork If the pull request is from a fork of the repository, this variable is set to True. Otherwise, it's set to False. Yes
System.PullRequest.PullRequestId The ID of the pull request that caused this build. For example: 17. (This variable is initialized only if the build ran because of a Git PR affected by a branch policy). No
System.PullRequest.PullRequestNumber The number of the pull request that caused this build. This variable is populated for pull requests from GitHub that have a different pull request ID and pull request number. This variable is only available in a YAML pipeline if the PR is affected by a branch policy. No
System.PullRequest.targetBranchName The name of the target branch for a pull request. This variable can be used in a pipeline to conditionally execute tasks or steps based on the target branch of the pull request. For example, you might want to trigger a different set of tests or code analysis tools depending on the branch that the changes are being merged into. No
System.PullRequest.SourceBranch The branch that is being reviewed in a pull request. For example: refs/heads/users/raisa/new-feature for Azure Repos. (This variable is initialized only if the build ran because of a Git PR affected by a branch policy). This variable is only available in a YAML pipeline if the PR is affected by a branch policy. No
System.PullRequest.SourceRepositoryURI The URL to the repo that contains the pull request. For example: https://dev.azure.com/ouraccount/_git/OurProject. No
System.PullRequest.TargetBranch The branch that is the target of a pull request. For example: refs/heads/main when your repository is in Azure Repos and main when your repository is in GitHub. This variable is initialized only if the build ran because of a Git PR affected by a branch policy. This variable is only available in a YAML pipeline if the PR is affected by a branch policy. No
System.StageAttempt Set to 1 the first time this stage is attempted, and increments every time the stage is retried. No
System.StageDisplayName The human-readable name given to a stage. No
System.StageName A string-based identifier for a stage, typically used for expressing dependencies and accessing output variables. No
System.TeamFoundationCollectionUri The URI of the TFS collection or Azure DevOps organization. For example: https://dev.azure.com/fabrikamfiber/.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Yes
System.TeamProject The name of the project that contains this build. Yes
System.TeamProjectId The ID of the project that this build belongs to. Yes
System.TimelineId A string-based identifier for the execution details and logs of a single pipeline run. No
TF_BUILD Set to True if the script is being run by a build task.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No

Checks variables (DevOps Server 2022)

Variable Description
Checks.StageAttempt Set to 1 the first time this stage is attempted, and increments every time the stage is retried.
This variable can only be used within an approval or check for an environment. For example, you could use $(Checks.StageAttempt) within an Invoke REST API check.
Add the stage attempt as a parameter.

Agent variables (DevOps Server 2020)

Note

You can use agent variables as environment variables in your scripts and as parameters in your build tasks. You cannot use them to customize the build number or to apply a version control label or tag.

Variable Description
Agent.BuildDirectory The local path on the agent where all folders for a given build pipeline are created. This variable has the same value as Pipeline.Workspace. For example: /home/vsts/work/1.
Agent.HomeDirectory The directory the agent is installed into. This contains the agent software. For example: c:\agent.
Agent.Id The ID of the agent.
Agent.JobName The name of the running job. This will usually be "Job" or "__default", but in multi-config scenarios, will be the configuration.
Agent.JobStatus The status of the build.
  • Canceled
  • Failed
  • Succeeded
  • SucceededWithIssues (partially successful)
  • Skipped (last job)
The environment variable should be referenced as AGENT_JOBSTATUS. The older agent.jobstatus is available for backwards compatibility.
Agent.MachineName The name of the machine on which the agent is installed.
Agent.Name The name of the agent that is registered with the pool.

If you're using a self-hosted agent, then this name gets set by you. See agents.
Agent.OS The operating system of the agent host. Valid values are:
  • Windows_NT
  • Darwin
  • Linux
If you're running in a container, the agent host and container might be running different operating systems.
Agent.OSArchitecture The operating system processor architecture of the agent host. Valid values are:
  • X86
  • X64
  • ARM processor
Agent.TempDirectory A temporary folder that is cleaned after each pipeline job. This directory is used by tasks such as .NET Core CLI task to hold temporary items like test results before they're published.
For example: /home/vsts/work/_temp for Ubuntu.
Agent.ToolsDirectory The directory used by tasks such as Node Tool Installer and Use Python Version to switch between multiple versions of a tool.

These tasks add tools from this directory to PATH so that subsequent build steps can use them.

Learn about managing this directory on a self-hosted agent.
Agent.WorkFolder The working directory for this agent. For example: c:\agent_work.

Note: This directory isn't guaranteed to be writable by pipeline tasks (for example, when mapped into a container)

Build variables (DevOps Server 2020)

When you use a variable in a template that is not marked as available in templates, the variable will not render. The variable won't render because its value is not accessible within the template's scope.

Variable Description Available in templates?
Build.ArtifactStagingDirectory The local path on the agent where any artifacts are copied to before being pushed to their destination. For example: c:\agent_work\1\a.

A typical way to use this folder is to publish your build artifacts with the Copy files and Publish build artifacts tasks.

Note: Build.ArtifactStagingDirectory and Build.StagingDirectory are interchangeable. This directory is purged before each new build, so you don't have to clean it up yourself.

See Artifacts in Azure Pipelines.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.BuildId The ID of the record for the completed build. No
Build.BuildNumber The name of the completed build, also known as the run number. You can specify what is included in this value.

A typical use of this variable is to make it part of the label format, which you specify on the repository tab.

Note: This value can contain whitespace or other invalid label characters. In these cases, the label format fails.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.BuildUri The URI for the build. For example: vstfs:///Build/Build/1430.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.BinariesDirectory The local path on the agent you can use as an output folder for compiled binaries.

By default, new build pipelines aren't set up to clean this directory. You can define your build to clean it up on the Repository tab.

For example: c:\agent_work\1\b.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.ContainerId The ID of the container for your artifact. When you upload an artifact in your pipeline, it's added to a container that is specific for that particular artifact. No
Build.DefinitionName The name of the build pipeline.

Note: This value can contain whitespace or other invalid label characters. In these cases, the label format will fail.
Yes
Build.DefinitionVersion The version of the build pipeline. Yes
Build.QueuedBy See "How are the identity variables set?".

Note: This value can contain whitespace or other invalid label characters. In these cases, the label format fails.
Yes
Build.QueuedById See "How are the identity variables set?". Yes
Build.Reason The event that caused the build to run.
  • Manual: A user manually queued the build.
  • IndividualCI: Continuous integration (CI) triggered by a Git push or a TFVC check-in.
  • BatchedCI: Continuous integration (CI) triggered by a Git push or a TFVC check-in, and the Batch changes was selected.
  • Schedule: Scheduled trigger.
  • ValidateShelveset: A user manually queued the build of a specific TFVC shelveset.
  • CheckInShelveset: Gated check-in trigger.
  • PullRequest: The build was triggered by a Git branch policy that requires a build.
  • BuildCompletion: The build was triggered by another build
  • ResourceTrigger: The build was triggered by a resource trigger or it was triggered by another build.
See Build pipeline triggers, Improve code quality with branch policies.
Yes
Build.Repository.Clean The value you've selected for Clean in the source repository settings.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.LocalPath The local path on the agent where your source code files are downloaded. For example: c:\agent_work\1\s.

By default, new build pipelines update only the changed files. You can modify how files are downloaded on the Repository tab.

Important note: If you check out only one Git repository, this path will be the exact path to the code.

If you check out multiple repositories, the behavior is as follows (and might differ from the value of the Build.SourcesDirectory variable):
  • If the checkout step for the self (primary) repository has no custom checkout path defined, or the checkout path is the multi-checkout default path $(Pipeline.Workspace)/s/&lt;RepoName&gt; for the self repository, the value of this variable will revert to its default value, which is $(Pipeline.Workspace)/s.
  • If the checkout step for the self (primary) repository does have a custom checkout path defined (and it's not its multi-checkout default path), this variable will contain the exact path to the self repository.
This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.ID The unique identifier of the repository.

This won't change, even if the name of the repository does.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.Name The name of the triggering repository.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.Provider The type of the triggering repository.
This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.Tfvc.Workspace Defined if your repository is Team Foundation Version Control. The name of the TFVC workspace used by the build agent.

For example, if the Agent.BuildDirectory is c:\agent_work\12 and the Agent.Id is 8, the workspace name could be: ws_12_8.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.Uri The URL for the triggering repository. For example:
This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.RequestedFor See "How are the identity variables set?".

Note: This value can contain whitespace or other invalid label characters. In these cases, the label format fails.
Yes
Build.RequestedForEmail See "How are the identity variables set?". Yes
Build.RequestedForId See "How are the identity variables set?". Yes
Build.SourceBranch The branch of the triggering repo the build was queued for. Some examples:
  • Git repo branch: refs/heads/main
  • Git repo pull request: refs/pull/1/merge
  • TFVC repo branch: $/teamproject/main
  • TFVC repo gated check-in: Gated_2016-06-06_05.20.51.4369;username@live.com
  • TFVC repo shelveset build: myshelveset;username@live.com
  • When your pipeline is triggered by a tag: refs/tags/your-tag-name
When you use this variable in your build number format, the forward slash characters (/) are replaced with underscore characters _).

Note: In TFVC, if you're running a gated check-in build or manually building a shelveset, you cannot use this variable in your build number format.
Yes
Build.SourceBranchName The name of the branch in the triggering repo the build was queued for.
  • Git repo branch, pull request, or tag: The last path segment in the ref. For example, in refs/heads/main this value is main. In refs/heads/feature/tools this value is tools. In refs/tags/your-tag-name this value is your-tag-name.
  • TFVC repo branch: The last path segment in the root server path for the workspace. For example, in $/teamproject/main this value is main.
  • TFVC repo gated check-in or shelveset build is the name of the shelveset. For example, Gated_2016-06-06_05.20.51.4369;username@live.com or myshelveset;username@live.com.
Note: In TFVC, if you're running a gated check-in build or manually building a shelveset, you can't use this variable in your build number format.
Yes
Build.SourcesDirectory The local path on the agent where your source code files are downloaded. For example: c:\agent_work\1\s.

By default, new build pipelines update only the changed files.

Important note: If you check out only one Git repository, this path is the exact path to the code. If you check out multiple repositories, it reverts to its default value, which is $(Pipeline.Workspace)/s, even if the self (primary) repository is checked out to a custom path different from its multi-checkout default path $(Pipeline.Workspace)/s/<RepoName> (in this respect, the variable differs from the behavior of the Build.Repository.LocalPath variable).

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.SourceVersion The latest version control change of the triggering repo that is included in this build.
This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Yes
Build.SourceVersionMessage The comment of the commit or changeset for the triggering repo. We truncate the message to the first line or 200 characters, whichever is shorter.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.

Also, this variable is only available on the step level and is not available in the job or stage levels (that is, the message isn't extracted until the job had started and checked out the code).

Note: This variable is available in TFS 2015.4.

Note: The Build.SourceVersionMessage variable does not work with classic build pipelines in Bitbucket repositories when Batch changes while a build is in progress is enabled.
No
Build.StagingDirectory The local path on the agent where any artifacts are copied to before being pushed to their destination. For example: c:\agent_work\1\a.

A typical way to use this folder is to publish your build artifacts with the Copy files and Publish build artifacts tasks.

Note: Build.ArtifactStagingDirectory and Build.StagingDirectory are interchangeable. This directory is purged before each new build, so you don't have to clean it up yourself.

See Artifacts in Azure Pipelines.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.Repository.Git.SubmoduleCheckout The value you've selected for Checkout submodules on the repository tab. With multiple repos checked out, this value tracks the triggering repository's setting.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.SourceTfvcShelveset Defined if your repository is Team Foundation Version Control.

If you're running a gated build or a shelveset build, this is set to the name of the shelveset you're building.

Note: This variable yields a value that is invalid for build use in a build number format.
No
Build.TriggeredBy.BuildId If the build was triggered by another build, then this variable is set to the BuildID of the triggering build. In Classic pipelines, this variable is triggered by a build completion trigger.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.TriggeredBy.DefinitionId If the build was triggered by another build, then this variable is set to the DefinitionID of the triggering build. In Classic pipelines, this variable is triggered by a build completion trigger.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.TriggeredBy.DefinitionName If the build was triggered by another build, then this variable is set to the name of the triggering build pipeline. In Classic pipelines, this variable is triggered by a build completion trigger.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.TriggeredBy.BuildNumber If the build was triggered by another build, then this variable is set to the number of the triggering build. In Classic pipelines, this variable is triggered by a build completion trigger.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Build.TriggeredBy.ProjectID If the build was triggered by another build, then this variable is set to ID of the project that contains the triggering build. In Classic pipelines, this variable is triggered by a build completion trigger.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
Common.TestResultsDirectory The local path on the agent where the test results are created. For example: c:\agent_work\1\TestResults.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No

Pipeline variables (DevOps Server 2020)

Variable Description
Pipeline.Workspace Workspace directory for a particular pipeline. This variable has the same value as Agent.BuildDirectory. For example, /home/vsts/work/1.

Deployment job variables (DevOps Server 2020)

These variables are scoped to a specific Deployment job and will be resolved only at job execution time.

Variable Description
Environment.Name Name of the environment targeted in the deployment job to run the deployment steps and record the deployment history. For example, smarthotel-dev.
Environment.Id ID of the environment targeted in the deployment job. For example, 10.
Environment.ResourceName Name of the specific resource within the environment targeted in the deployment job to run the deployment steps and record the deployment history. For example, bookings which is a Kubernetes namespace that has been added as a resource to the environment smarthotel-dev.
Environment.ResourceId ID of the specific resource within the environment targeted in the deployment job to run the deployment steps. For example, 4.

System variables (DevOps Server 2020)

When you use a variable in a template that is not marked as available in templates, the variable will not render. The variable won't render because its value is not accessible within the template's scope.

Variable Description Available in templates?
System.AccessToken Use the OAuth token to access the REST API.

Use System.AccessToken from YAML scripts.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Yes
System.CollectionId The GUID of the TFS collection or Azure DevOps organization Yes
System.CollectionUri A string Team Foundation Server collection URI. Yes
System.DefaultWorkingDirectory The local path on the agent where your source code files are downloaded. For example: c:\agent_work\1\s

By default, new build pipelines update only the changed files. You can modify how files are downloaded on the Repository tab.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No
System.DefinitionId The ID of the build pipeline. Yes
System.HostType Set to build if the pipeline is a build. For a release, the values are deployment for a Deployment group job, gates during evaluation of gates, and release for other (Agent and Agentless) jobs. Yes
System.JobAttempt Set to 1 the first time this job is attempted, and increments every time the job is retried. No
System.JobDisplayName The human-readable name given to a job. No
System.JobId A unique identifier for a single attempt of a single job. The value is unique to the current pipeline. No
System.JobName The name of the job, typically used for expressing dependencies and accessing output variables. No
System.PhaseAttempt Set to 1 the first time this phase is attempted, and increments every time the job is retried.

Note: "Phase" is a mostly redundant concept, which represents the design-time for a job (whereas job was the runtime version of a phase). We've mostly removed the concept of "phase" from Azure Pipelines. Matrix and multi-config jobs are the only place where "phase" is still distinct from "job". One phase can instantiate multiple jobs, which differ only in their inputs.
No
System.PhaseDisplayName The human-readable name given to a phase. No
System.PhaseName A string-based identifier for a job, typically used for expressing dependencies and accessing output variables. No
System.StageAttempt Set to 1 the first time this stage is attempted, and increments every time the job is retried. No
System.StageDisplayName The human-readable name given to a stage. No
System.StageName A string-based identifier for a stage, typically used for expressing dependencies and accessing output variables. Yes
System.PullRequest.IsFork If the pull request is from a fork of the repository, this variable is set to True. Otherwise, it's set to False. Yes
System.PullRequest.PullRequestId The ID of the pull request that caused this build. For example: 17. (This variable is initialized only if the build ran because of a Git PR affected by a branch policy). No
System.PullRequest.PullRequestNumber The number of the pull request that caused this build. This variable is populated for pull requests from GitHub which have a different pull request ID and pull request number. This variable is only available in a YAML pipeline if the PR is affected by a branch policy. No
System.PullRequest.targetBranchName The name of the target branch for a pull request. This variable can be used in a pipeline to conditionally execute tasks or steps based on the target branch of the pull request. For example, you might want to trigger a different set of tests or code analysis tools depending on the branch that the changes are being merged into. No
System.PullRequest.SourceBranch The branch that is being reviewed in a pull request. For example: refs/heads/users/raisa/new-feature. (This variable is initialized only if the build ran because of a Git PR affected by a branch policy). This variable is only available in a YAML pipeline if the PR is affected by a branch policy. No
System.PullRequest.SourceCommitId The commit that is being reviewed in a pull request. (This variable is initialized only if the build ran because of a Git PR affected by a branch policy). This variable is only available in a YAML pipeline if the PR is affected by a branch policy.
System.PullRequest.SourceRepositoryURI The URL to the repo that contains the pull request. For example: https://dev.azure.com/ouraccount/_git/OurProject. No
System.PullRequest.TargetBranch The branch that is the target of a pull request. For example: refs/heads/main when your repository is in Azure Repos and main when your repository is in GitHub. This variable is initialized only if the build ran because of a Git PR affected by a branch policy. This variable is only available in a YAML pipeline if the PR is affected by a branch policy. No
System.TeamFoundationCollectionUri The URI of the team foundation collection. For example: https://dev.azure.com/fabrikamfiber/.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Yes
System.TeamProject The name of the project that contains this build. Yes
System.TeamProjectId The ID of the project that this build belongs to. Yes
TF_BUILD Set to True if the script is being run by a build task.

This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
No

Agent variables (DevOps Server 2019)

Note

You can use agent variables as environment variables in your scripts and as parameters in your build tasks. You cannot use them to customize the build number or to apply a version control label or tag.

Variable Description
Agent.BuildDirectory The local path on the agent where all folders for a given build pipeline are created. For example: c:\agent_work\1.
Agent.HomeDirectory The directory the agent is installed into. This contains the agent software. For example: c:\agent.
Agent.Id The ID of the agent.
Agent.JobName The name of the running job. This will usually be "Job" or "__default", but in multi-config scenarios, will be the configuration.
Agent.JobStatus The status of the build.
  • Canceled
  • Failed
  • Succeeded
  • SucceededWithIssues (partially successful)
  • Skipped (last job)
The environment variable should be referenced as AGENT_JOBSTATUS. The older agent.jobstatus is available for backwards compatibility.
Agent.MachineName The name of the machine on which the agent is installed.
Agent.Name The name of the agent that is registered with the pool.

If you're using a self-hosted agent, then this name get set by you. See agents.
Agent.OS The operating system of the agent host. Valid values are:
  • Windows_NT
  • Darwin
  • Linux
If you're running in a container, the agent host and container may be running different operating systems.
Agent.OSArchitecture The operating system processor architecture of the agent host. Valid values are:
  • X86
  • X64
  • ARM processor
Agent.TempDirectory A temporary folder that is cleaned after each pipeline job. This directory is used by tasks such as .NET Core CLI task to hold temporary items like test results before they're published.
Agent.ToolsDirectory The directory used by tasks such as Node Tool Installer and Use Python Version to switch between multiple versions of a tool.

These tasks add tools from this directory to PATH so that subsequent build steps can use them.

Learn about managing this directory on a self-hosted agent.
Agent.WorkFolder The working directory for this agent. For example: c:\agent_work.

This directory isn't guaranteed to be writable by pipeline tasks (for example, when mapped into a container).

Build variables (DevOps Server 2019)

Variable Description
Build.ArtifactStagingDirectory The local path on the agent where any artifacts are copied to before being pushed to their destination. For example: c:\agent_work\1\a.

A typical way to use this folder is to publish your build artifacts with the Copy files and Publish build artifacts tasks.

Note: Build.ArtifactStagingDirectory and Build.StagingDirectory are interchangeable. This directory is purged before each new build, so you don't have to clean it up yourself.

See Artifacts in Azure Pipelines.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Build.BuildId The ID of the record for the completed build.
Build.BuildNumber The name of the completed build. You can specify the build number format that generates this value in the pipeline options.

A typical use of this variable is to make it part of the label format, which you specify on the repository tab.

Note: This value can contain whitespace or other invalid label characters. In these cases, the label format fails.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Build.BuildUri The URI for the build. For example: vstfs:///Build/Build/1430.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Build.BinariesDirectory The local path on the agent you can use as an output folder for compiled binaries.

By default, new build pipelines aren't set up to clean this directory. You can define your build to clean it up on the Repository tab.

For example: c:\agent_work\1\b.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Build.DefinitionName The name of the build pipeline.

Note: This value can contain whitespace or other invalid label characters. In these cases, the label format will fail.
Build.DefinitionVersion The version of the build pipeline.
Build.QueuedBy See "How are the identity variables set?".

Note: This value can contain whitespace or other invalid label characters. In these cases, the label format fails.
Build.QueuedById See "How are the identity variables set?".
Build.Reason The event that caused the build to run.
  • Manual: A user manually queued the build.
  • IndividualCI: Continuous integration (CI) triggered by a Git push or a TFVC check-in.
  • BatchedCI: Continuous integration (CI) triggered by a Git push or a TFVC check-in, and the Batch changes was selected.
  • Schedule: Scheduled trigger.
  • ValidateShelveset: A user manually queued the build of a specific TFVC shelveset.
  • CheckInShelveset: Gated check-in trigger.
  • PullRequest: The build was triggered by a Git branch policy that requires a build.
  • BuildCompletion: The build was triggered by another build.
See Build pipeline triggers, Improve code quality with branch policies.
Build.Repository.Clean The value you've selected for Clean in the source repository settings.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Build.Repository.LocalPath The local path on the agent where your source code files are downloaded. For example: c:\agent_work\1\s

By default, new build pipelines update only the changed files. You can modify how files are downloaded on the Repository tab.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.

This variable is synonymous with Build.SourcesDirectory.
Build.Repository.Name The name of the repository.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Build.Repository.Provider The type of repository you selected.
This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Build.Repository.Tfvc.Workspace Defined if your repository is Team Foundation Version Control. The name of the TFVC workspace used by the build agent.

For example, if the Agent.BuildDirectory is c:\agent_work\12 and the Agent.Id is 8, the workspace name could be: ws_12_8.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Build.Repository.Uri The URL for the repository. For example:
This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Build.RequestedFor See "How are the identity variables set?".

Note: This value can contain whitespace or other invalid label characters. In these cases, the label format fails.
Build.RequestedForEmail See "How are the identity variables set?".
Build.RequestedForId See "How are the identity variables set?".
Build.SourceBranch The branch the build was queued for. Some examples:
  • Git repo branch: refs/heads/main
  • Git repo pull request: refs/pull/1/merge
  • TFVC repo branch: $/teamproject/main
  • TFVC repo gated check-in: Gated_2016-06-06_05.20.51.4369;username@live.com
  • TFVC repo shelveset build: myshelveset;username@live.com
When you use this variable in your build number format, the forward slash characters (/) are replaced with underscore characters (_).

Note: In TFVC, if you're running a gated check-in build or manually building a shelveset, you can't use this variable in your build number format.
Build.SourceBranchName The name of the branch the build was queued for.
  • Git repo branch, pull request, or tag: The last path segment in the ref. For example, in refs/heads/main this value is main. In refs/heads/feature/tools this value is tools. In refs/tags/your-tag-name this value is your-tag-name.
  • TFVC repo branch: The last path segment in the root server path for the workspace. For example in $/teamproject/main this value is main.
  • TFVC repo gated check-in or shelveset build is the name of the shelveset. For example, Gated_2016-06-06_05.20.51.4369;username@live.com or myshelveset;username@live.com.
Note: In TFVC, if you're running a gated check-in build or manually building a shelveset, you can't use this variable in your build number format.
Build.SourcesDirectory The local path on the agent where your source code files are downloaded. For example: c:\agent_work\1\s.

By default, new build pipelines update only the changed files. You can modify how files are downloaded on the Repository tab.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.

This variable is synonymous with Build.Repository.LocalPath.
Build.SourceVersion The latest version control change that is included in this build.
This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Build.SourceVersionMessage The comment of the commit or changeset. We truncate the message to the first line or 200 characters, whichever is shorter.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.

Note: This variable is available in TFS 2015.4.

Note: The Build.SourceVersionMessage variable does not work with classic build pipelines in Bitbucket repositories when Batch changes while a build is in progress is enabled.
Build.StagingDirectory The local path on the agent where any artifacts are copied to before being pushed to their destination. For example: c:\agent_work\1\a.

A typical way to use this folder is to publish your build artifacts with the Copy files and Publish build artifacts tasks.

Note: Build.ArtifactStagingDirectory and Build.StagingDirectory are interchangeable. This directory is purged before each new build, so you don't have to clean it up yourself.

See Artifacts in Azure Pipelines.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Build.Repository.Git.SubmoduleCheckout The value you've selected for Checkout submodules on the repository tab.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Build.SourceTfvcShelveset Defined if your repository is Team Foundation Version Control.

If you're running a gated build or a shelveset build, this is set to the name of the shelveset you're building.

Note: This variable yields a value that is invalid for build use in a build number format.
Build.TriggeredBy.BuildId If the build was triggered by another build, then this variable is set to the BuildID of the triggering build.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Build.TriggeredBy.DefinitionId If the build was triggered by another build, then this variable is set to the DefinitionID of the triggering build.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Build.TriggeredBy.DefinitionName If the build was triggered by another build, then this variable is set to the name of the triggering build pipeline.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Build.TriggeredBy.BuildNumber If the build was triggered by another build, then this variable is set to the number of the triggering build.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Build.TriggeredBy.ProjectID If the build was triggered by another build, then this variable is set to ID of the project that contains the triggering build.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
Common.TestResultsDirectory The local path on the agent where the test results are created. For example: c:\agent_work\1\TestResults.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.

System variables (DevOps Server 2019)

Example PowerShell script: access REST API

Variable Description
System.AccessToken Use the OAuth token to access the REST API.

Use System.AccessToken from YAML scripts.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
System.CollectionId The GUID of the TFS collection or Azure DevOps organization
System.DefaultWorkingDirectory The local path on the agent where your source code files are downloaded. For example: c:\agent_work\1\s

By default, new build pipelines update only the changed files. You can modify how files are downloaded on the Repository tab.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
System.DefinitionId The ID of the build pipeline.
System.HostType Set to build if the pipeline is a build. For a release, the values are deployment for a Deployment group job and release for an Agent job.
System.PullRequest.IsFork If the pull request is from a fork of the repository, this variable is set to True. Otherwise, it is set to False.
System.PullRequest.PullRequestId The ID of the pull request that caused this build. For example: 17. (This variable is initialized only if the build ran because of a Git PR affected by a branch policy.)
System.PullRequest.PullRequestNumber The number of the pull request that caused this build. This variable is populated for pull requests from GitHub, which have a different pull request ID and pull request number.
System.PullRequest.SourceBranch The branch that is being reviewed in a pull request. For example: refs/heads/users/raisa/new-feature. (This variable is initialized only if the build ran because of a Git PR affected by a branch policy.)
System.PullRequest.SourceCommitId The commit that is being reviewed in a pull request. (This variable is initialized only if the build ran because of a Git PR affected by a branch policy.)
System.PullRequest.SourceRepositoryURI The URL to the repo that contains the pull request. For example: https://dev.azure.com/ouraccount/_git/OurProject. (This variable is initialized only if the build ran because of a Azure Repos Git PR affected by a branch policy. It isn't initialized for GitHub PRs.)
System.PullRequest.TargetBranch The branch that is the target of a pull request. For example: refs/heads/main. This variable is initialized only if the build ran because of a Git PR affected by a branch policy.
System.TeamFoundationCollectionUri The URI of the team foundation collection. For example: https://dev.azure.com/fabrikamfiber/.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
System.TeamProject The name of the project that contains this build.
System.TeamProjectId The ID of the project that this build belongs to.
TF_BUILD Set to True if the script is being run by a build task.

This variable is agent-scoped. It can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.

How are the identity variables set?

The value depends on what caused the build and are specific to Azure Repos repositories.

If the build is triggered... Then the Build.QueuedBy and Build.QueuedById values are based on... Then the Build.RequestedFor and Build.RequestedForId values are based on...
In Git or by the Continuous integration (CI) triggers The system identity, for example: [DefaultCollection]\Project Collection Service Accounts The person who pushed or checked in the changes.
In Git or by a branch policy build. The system identity, for example: [DefaultCollection]\Project Collection Service Accounts The person who checked in the changes.
In TFVC by a gated check-in trigger The person who checked in the changes. The person who checked in the changes.
In Git or TFVC by the Scheduled triggers The system identity, for example: [DefaultCollection]\Project Collection Service Accounts The system identity, for example: [DefaultCollection]\Project Collection Service Accounts
Because you clicked the Queue build button You You