Instance-level public IP address configuration in Cloud Services

Article
04/11/2024

This article discusses how to configure an instance-level public IP address (PIP) in Microsoft Azure Cloud Services (classic) and Azure Cloud Services (extended support). Unlike a virtual IP address (VIP), an instance-level public IP address isn't load-balanced. A VIP is assigned to the cloud service, and all virtual machines and role instances in the cloud service share that VIP. However, a public IP address (PIP) is associated with only the network adapter of a single instance. The public IP address is useful in multi-instance deployments in which each instance can be reachable independently from the internet. The following diagram illustrates the value of the PIP and differentiates it from the VIP.

In the diagram, network traffic that's sent to the VIP is shown as load-balanced between datacenter IP address (DIP) 1 and DIP 2. However, traffic that's sent to PIP 1 always goes to DIP 1, and traffic that's sent to PIP 2 always goes to DIP 2. A datacenter IP address is the private IP address of the virtual machine (VM).

For more information, see the Instance-level public IP address Azure Blog article.

Procedure for Azure Cloud Services (classic)

Configure an instance-level public IP address by role:

<?xml version="1.0" encoding="utf-8"?>
<ServiceConfiguration
        serviceName="TestVirtualnetwork"
        xmlns="http://schemas.microsoft.com/ServiceHosting/2008/10/ServiceConfiguration"
        osFamily="6"
        osVersion="*"
        schemaVersion="2015-04.2.6">
    <Role name="WebRole1">
        <Instances count="1" />
        <ConfigurationSettings>
            <Setting name="APPINSIGHTS_INSTRUMENTATIONKEY" value="xxx" />
        </ConfigurationSettings>
    </Role>
    <Role name="WebRole2">
        <Instances count="1" />
        <ConfigurationSettings>
            <Setting name="APPINSIGHTS_INSTRUMENTATIONKEY" value="xxx" />
        </ConfigurationSettings>
    </Role>
    <Role name="WebRole3">
        <Instances count="1" />
        <ConfigurationSettings>
            <Setting name="APPINSIGHTS_INSTRUMENTATIONKEY" value="xxx" />
        </ConfigurationSettings>
    </Role>
    <Role name="WebRole4">
        <Instances count="1" />
        <ConfigurationSettings>
            <Setting name="APPINSIGHTS_INSTRUMENTATIONKEY" value="xxx" />
        </ConfigurationSettings>
    </Role>
    <NetworkConfiguration>
        <VirtualNetworkSite name="Group RESOURCE_GROUP VIRTUAL_NETWORK_NAME" />
        <AddressAssignments>
            <InstanceAddress roleName="WebRole1">
                <Subnets><Subnet name="subnet001" /></Subnets>
                <PublicIPs>
                    <PublicIP name="PubIP" domainNameLabel="pip" />  <!-- with domain -->
                </PublicIPs>
            </InstanceAddress>
            <InstanceAddress roleName="WebRole2">
                <Subnets><Subnet name="subnet003" /></Subnets>
                <PublicIPs>
                    <PublicIP name="PubIP"/>                         <!-- without domain -->
                </PublicIPs>
            </InstanceAddress>
        </AddressAssignments>
    </NetworkConfiguration>
</ServiceConfiguration>

Get the current public IP address of a role by using one of the following methods.

PowerShell
IMDS

For each role instance, run the Get-AzureRole PowerShell cmdlet. This cmdlet is based on the Azure.Service module. By using the IP address configuration in the previous step, we can see the difference between the instance details of each role instance.

View the details of the WebRole2 role, whose public IP name doesn't have a domain name label:

$roleParams = @{
    ServiceName = "<cloud-service-name>"
    Slot = "Production"
    RoleName = "WebRole2"
    InstanceDetails = $true
}
Get-AzureRole @roleParams

The cmdlet output resembles the following text:

InstanceEndpoints            : {Microsoft.WindowsAzure.Plugins.RemoteForwarder.RdpInput, Endpoint1}
InstanceErrorCode            : 
InstanceFaultDomain          : 0
InstanceName                 : WebRole2_IN_0
InstanceSize                 : Standard_D1_v2
InstanceStateDetails         : 
InstanceStatus               : ReadyRole
InstanceUpgradeDomain        : 0
RoleName                     : WebRole2
DeploymentID                 : 0123456789abcdef0123456789abcdef
IPAddress                    : 10.2.2.5
PublicIPAddress              : 20.115.22.157
PublicIPName                 : PubIP
PublicIPIdleTimeoutInMinutes : 
PublicIPDomainNameLabel      : 
PublicIPFqdns                : {}
ServiceName                  : contoso-vnet-pip
OperationDescription         : Get-AzureRole
OperationId                  : 12345678-9abc-def0-1234-56789abcdef0
OperationStatus              : Succeeded

Now view the details of the WebRole1 role, which uses the same public IP name but also has a domain name label:

$roleParams = @{
    ServiceName = "<cloud-service-name>"
    Slot = "Production"
    RoleName = "WebRole1"
    InstanceDetails = $true
}
Get-AzureRole @roleParams

In the cmdlet output, the InstanceEndpoints, InstanceName, InstanceStatus, RoleName, IPAddress, PublicIPAddress, PublicIPDomainNameLabel, PublicIPFqdns, and OperationId values are different:

InstanceEndpoints            : {Endpoint1}
InstanceErrorCode            : 
InstanceFaultDomain          : 0
InstanceName                 : WebRole1_IN_0
InstanceSize                 : Standard_D1_v2
InstanceStateDetails         : 
InstanceStatus               : StoppedVM
InstanceUpgradeDomain        : 0
RoleName                     : WebRole1_IN_0
DeploymentID                 : 0123456789abcdef0123456789abcdef
IPAddress                    : 10.2.0.4
PublicIPAddress              : 20.168.229.192
PublicIPName                 : PubIP
PublicIPIdleTimeoutInMinutes : 
PublicIPDomainNameLabel      : pip
PublicIPFqdns                : {pip.contoso-vnet-pip.cloudapp.net, pip.0.contoso-vnet-pip.cloudapp.net}
ServiceName                  : contoso-vnet-pip
OperationDescription         : Get-AzureRole
OperationId                  : 23456789-abcd-ef01-2345-6789abcdef01
OperationStatus              : Succeeded

The Azure Instance Metadata Service (IMDS) provides information about VM instances that are currently running. You can use IMDS to review the network adapter level setting of your VM. On each VM instance, run the Invoke-RestMethod PowerShell cmdlet in the following code snippet:

$restMethodParams = @{
    Method = "Get"
    Uri = "http://169.254.169.254/metadata/instance?api-version=2021-02-01"
    Headers = @{"Metadata" = "true"}
    NoProxy = $true
}
Invoke-RestMethod @restMethodParams | ConvertTo-Json -Depth 64

The cmdlet output resembles the following JSON code:

{
  "network": {
    "interface": [
      {
        "ipv4": {
          "ipAddress": [
            {
              "privateIpAddress": "10.2.2.5",
              "publicIpAddress": "20.115.22.157"
            }
          ],
          "subnet": [
            {
              "address": "10.2.2.0",
              "prefix": "24"
            }
          ]
        },
        "ipv6": {
          "ipAddress": []
        },
        "macAddress": "0003FF95519C"
      }
    ]
  }
}

Procedure for Azure Cloud Services (extended support)

Configure an instance-level public IP address by role:

<?xml version="1.0" encoding="utf-16"?>
<ServiceConfiguration
        xmlns:xsd="http://www.w3.org/2001/XMLSchema"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        serviceName="Test_cloudservice"
        osFamily="6"
        osVersion="*"
        schemaVersion="2015-04.2.6"
        xmlns="http://schemas.microsoft.com/ServiceHosting/2008/10/ServiceConfiguration">
    <Role name="TestWebRole">
        <ConfigurationSettings>
            <Setting
                    name="Microsoft.WindowsAzure.Plugins.Diagnostics.ConnectionString"
                    value="UseDevelopmentStorage=true" />
        </ConfigurationSettings>
        <Instances count="2" />
    </Role>
    <Role name="TestWorkerRole">
        <ConfigurationSettings>
            <Setting
                    name="Microsoft.WindowsAzure.Plugins.Diagnostics.ConnectionString"
                    value="UseDevelopmentStorage=true" />
        </ConfigurationSettings>
        <Instances count="1" />
    </Role>
    <NetworkConfiguration>
        <VirtualNetworkSite name="test001VNet" />
        <AddressAssignments>
            <InstanceAddress roleName="TestWebRole">
                <Subnets>
                    <Subnet name="default" />
                </Subnets>
                <PublicIPs>
                    <PublicIP name="PubIP" domainNameLabel="pip" />
                </PublicIPs>
            </InstanceAddress>
            <InstanceAddress roleName="TestWorkerRole">
                <Subnets>
                    <Subnet name="default" />
                </Subnets>
            </InstanceAddress>
            <ReservedIPs>
                <ReservedIP name="Group TESTCSES cses-prod" />
            </ReservedIPs>
        </AddressAssignments>
    </NetworkConfiguration>
</ServiceConfiguration>

Use the PublicIPAddress In CloudService - List Cloud Service Public IP Addresses REST API to get the public IP address of the network adapter. The following code snippet shows an example JSON response:

{
  "value": [
    {
      "name": "PubIP",
      "id": "/subscriptions/<your-subscription-guid>/resourceGroups/TESTCSES/providers/Microsoft.Compute/cloudServices/testcsesv2/roleInstances/TestWebRole_IN_0/networkInterfaces/nic1/ipConfigurations/ipconfig1/publicIPAddresses/PubIP",
      "etag": "W/\"3456789a-bcde-f012-3456-789abcdef012\"",
      "location": "eastus",
      "properties": {
        "provisioningState": "Succeeded",
        "resourceGuid": "<your-resource-guid>",
        "ipAddress": "20.169.153.231",
        "publicIPAddressVersion": "IPv4",
        "publicIPAllocationMethod": "Dynamic",
        "idleTimeoutInMinutes": 4,
        "dnsSettings": {
          "domainNameLabel": "pip.0.cses-prod",
          "fqdn": "pip.0.cses-prod.eastus.cloudapp.azure.com"
        },
        "ipTags": [],
        "ipConfiguration": {
          "id": "/subscriptions/<your-subscription-guid>/resourceGroups/TESTCSES/providers/Microsoft.Compute/cloudServices/testcsesv2/roleInstances/TestWebRole_IN_0/networkInterfaces/nic1/ipConfigurations/ipconfig1"
        }
      },
      "sku": {
        "name": "Basic",
        "tier": "Regional"
      }
    },
    {
      "name": "PubIP",
      "id": "/subscriptions/<your-subscription-guid>/resourceGroups/TESTCSES/providers/Microsoft.Compute/cloudServices/testcsesv2/roleInstances/TestWebRole_IN_1/networkInterfaces/nic1/ipConfigurations/ipconfig1/publicIPAddresses/PubIP",
      "etag": "W/\"456789ab-cdef-0123-4567-89abcdef0123\"",
      "location": "eastus",
      "properties": {
        "provisioningState": "Succeeded",
        "resourceGuid": "<your-resource-guid>",
        "ipAddress": "20.231.68.190",
        "publicIPAddressVersion": "IPv4",
        "publicIPAllocationMethod": "Dynamic",
        "idleTimeoutInMinutes": 4,
        "dnsSettings": {
          "domainNameLabel": "pip.1.cses-prod",
          "fqdn": "pip.1.cses-prod.eastus.cloudapp.azure.com"
        },
        "ipTags": [],
        "ipConfiguration": {
          "id": "/subscriptions/<your-subscription-guid>/resourceGroups/TESTCSES/providers/Microsoft.Compute/cloudServices/testcsesv2/roleInstances/TestWebRole_IN_1/networkInterfaces/nic1/ipConfigurations/ipconfig1"
        }
      },
      "sku": {
        "name": "Basic",
        "tier": "Regional"
      }
    }
  ]
}

Although the two objects in the value array both have a name key value of PubIP, there are differences in the IP address and DNS settings within the respective properties keys. The ipAddress key has a value of 20.169.153.231 in the first array object and 20.231.68.190 in the second array object. The dnsSettings key has a value of pip.0.cses-prod in the first array object and pip.1.cses-prod in the second array object.

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Instance-level public IP address configuration in Cloud Services

Procedure for Azure Cloud Services (classic)

Procedure for Azure Cloud Services (extended support)

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