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

Eureka Server for Spring is a service registry that allows microservices to register themselves and discover other services. Available as an Azure Container Apps component, you can bind your container app to a Eureka Server for Spring for automatic registration with the Eureka server.

In this tutorial, you learn to:

Prerequisites

To complete this project, you need the following items:

Considerations

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

Setup

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

Execute the following commands to create your resource group, 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-services-resource-group
   export ENVIRONMENT=my-environment
   export JAVA_COMPONENT_NAME=eureka
   export APP_NAME=sample-service-eureka-client
   export IMAGE="mcr.microsoft.com/javacomponents/samples/sample-service-eureka-client:latest"
   

   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 Eureka Server for Spring Java component.
   IMAGE	The container image used in your container app.

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
   

Use the Eureka Server for Spring Java component

Now that you have an existing environment, you can create your container app and bind it to a Java component instance of Eureka Server for Spring.

1. Create the Eureka Server for Spring Java component.

   az containerapp env java-component eureka-server-for-spring create \
     --environment $ENVIRONMENT \
     --resource-group $RESOURCE_GROUP \
     --name $JAVA_COMPONENT_NAME
   

2. Update the Eureka Server for Spring Java component configuration.

   az containerapp env java-component eureka-server-for-spring update \
     --environment $ENVIRONMENT \
     --resource-group $RESOURCE_GROUP \
     --name $JAVA_COMPONENT_NAME 
     --configuration eureka.server.renewal-percent-threshold=0.85 eureka.server.eviction-interval-timer-in-ms=10000
   

3. Create the container app and bind to the Eureka Server for Spring.

   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 \
     --bind $JAVA_COMPONENT_NAME \
     --query properties.configuration.ingress.fqdn
   

   This command returns the URL of your container app that consumes registers with the Eureka server component. Copy the URL to a text editor so you can use it in a coming step.

   Navigate top the /allRegistrationStatus route view all applications registered with the Eureka Server for Spring.

   The binding injects several configurations into the application as environment variables, primarily the eureka.client.service-url.defaultZone property. This property indicates the internal endpoint of the Eureka Server Java component.

   The binding also injects the following properties:

   "eureka.client.register-with-eureka":    "true"
   "eureka.instance.prefer-ip-address":     "true"
   

   The eureka.client.register-with-eureka property is set to true to enforce registration with the Eureka server. This registration overwrites the local setting in application.properties, from the config server and so on. If you want to set it to false, you can overwrite it by setting an environment variable in your container app.

   The eureka.instance.prefer-ip-address is set to true due to the specific DNS resolution rule in the container app environment. Don't modify this value so you don't break the binding.

   You can also remove a binding from your application.

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