Tutorial: Connect to a managed Config Server for Spring in Azure Container Apps (preview)

Config Server for Spring provides a centralized location to make configuration data available to multiple applications. In this article, you learn to connect an app hosted in Azure Container Apps to a Java Config Server for Spring instance.

The Config Server for Spring component uses a GitHub repository as the source for configuration settings. Configuration values are made available to your container app via a binding between the component and your container app. As values change in the configuration server, they automatically flow to your application, all without requiring you to recompile or redeploy your application.

In this tutorial, you learn to:

Prerequisites

To complete this project, you need the following items:

Considerations

When running in Config Server for Spring in Azure Container Apps, be aware of the following details:

Setup

Before you begin to work with the Config Server for Spring, you first need to create the required resources.

Execute the following commands to create your resource group and Container Apps environment.

1. Create variables to support your application configuration. These values are provided for you for the purposes of this lesson.

   export LOCATION=eastus
   export RESOURCE_GROUP=my-spring-cloud-resource-group
   export ENVIRONMENT=my-spring-cloud-environment
   export JAVA_COMPONENT_NAME=myconfigserver
   export APP_NAME=my-config-client
   export IMAGE="mcr.microsoft.com/javacomponents/samples/sample-service-config-client:latest"
   export URI="https://github.com/Azure-Samples/azure-spring-cloud-config-java-aca.git"
   

   Variable	Description
   LOCATION	The Azure region location where you create your container app and Java component.
   ENVIRONMENT	The Azure Container Apps environment name for your demo application.
   RESOURCE_GROUP	The Azure resource group name for your demo application.
   JAVA_COMPONENT_NAME	The name of the Java component created for your container app. In this case, you create a Config Server for Spring Java component.
   IMAGE	The container image used in your container app.
   URI	You can replace the URI with your git repo url, if it's private, add the related authentication configurations such as spring.cloud.config.server.git.username and spring.cloud.config.server.git.password.

2. Log in to Azure with the Azure CLI.

   az login
   

3. Create a resource group.

   az group create --name $RESOURCE_GROUP --location $LOCATION
   

4. Create your container apps environment.

   az containerapp env create \
     --name $ENVIRONMENT \
     --resource-group $RESOURCE_GROUP \
     --location $LOCATION
   

   This environment is used to host both the Config Server for Spring component and your container app.

Use the Config Server for Spring Java component

Now that you have a Container Apps environment, you can create your container app and bind it to a Config Server for Spring component. When you bind your container app, configuration values automatically synchronize from the Config Server component to your application.

1. Create the Config Server for Spring Java component.

   az containerapp env java-component config-server-for-spring create \
     --environment $ENVIRONMENT \
     --resource-group $RESOURCE_GROUP \
     --name $JAVA_COMPONENT_NAME \
     --configuration spring.cloud.config.server.git.uri=$URI
   

2. Update the Config Server for Spring Java component.

   az containerapp env java-component config-server-for-spring update \
     --environment $ENVIRONMENT \
     --resource-group $RESOURCE_GROUP \
     --name $JAVA_COMPONENT_NAME \
     --configuration spring.cloud.config.server.git.uri=$URI spring.cloud.config.server.git.refresh-rate=60
   

   Here, you're telling the component where to find the repository that holds your configuration information via the uri property. The refresh-rate property tells Container Apps how often to check for changes in your git repository.

3. Create the container app that consumes configuration data.

   az containerapp create \
     --name $APP_NAME \
     --resource-group $RESOURCE_GROUP \
     --environment $ENVIRONMENT \
     --image $IMAGE \
     --min-replicas 1 \
     --max-replicas 1 \
     --ingress external \
     --target-port 8080 \
     --query properties.configuration.ingress.fqdn
   

   This command returns the URL of your container app that consumes configuration data. Copy the URL to a text editor so you can use it in a coming step.

   If you visit your app in a browser, the connectTimeout value returned is the default value of 0.

4. Bind to the Config Server for Spring.

   Now that the container app and Config Server are created, you bind them together with the update command to your container app.

   az containerapp update \
     --name $APP_NAME \
     --resource-group $RESOURCE_GROUP \
     --bind $JAVA_COMPONENT_NAME
   

   The --bind $JAVA_COMPONENT_NAME parameter creates the link between your container app and the configuration component.

   Once the container app and the Config Server component are bound together, configuration changes are automatically synchronized to the container app.

   When you visit the app's URL again, the value of connectTimeout is now 10000. This value comes from the git repo set in the $URI variable originally set as the source of the configuration component. Specifically, this value is drawn from the connectionTimeout property in the repo's application.yml file.

   The bind request injects configuration setting into the application as environment variables. These values are now available to the application code to use when fetching configuration settings from the config server.

   In this case, the following environment variables are available to the application:

   SPRING_CLOUD_CONFIG_URI=http://$JAVA_COMPONENT_NAME:80
   SPRING_CLOUD_CONFIG_COMPONENT_URI=http://$JAVA_COMPONENT_NAME:80
   SPRING_CONFIG_IMPORT=optional:configserver:$SPRING_CLOUD_CONFIG_URI
   

   If you want to customize your own SPRING_CONFIG_IMPORT, you can refer to the environment variable SPRING_CLOUD_CONFIG_COMPONENT_URI, for example, you can override by command line arguments, like Java -Dspring.config.import=optional:configserver:${SPRING_CLOUD_CONFIG_COMPONENT_URI}?fail-fast=true.

   You can also remove a binding from your application.

5. Unbind the Config Server for Spring Java component.

   To remove a binding from a container app, use the --unbind option.

   az containerapp update \
     --name $APP_NAME \
     --unbind $JAVA_COMPONENT_NAME \
     --resource-group $RESOURCE_GROUP
   

   When you visit the app's URL again, the value of connectTimeout changes to back to 0.

Clean up resources

The resources created in this tutorial have an effect on your Azure bill. If you aren't going to use these services long-term, run the following command to remove everything created in this tutorial.

az group delete \
  --resource-group $RESOURCE_GROUP

Next steps