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:

• Create a Eureka Server for Spring Java component
• Bind your container app to Eureka Server for Spring Java component

Important

This tutorial uses services that can affect your Azure bill. If you decide to follow along step-by-step, make sure you delete the resources featured in this article to avoid unexpected billing.

Prerequisites

To complete this project, you need the following items:

Requirement	Instructions
Azure account	An active subscription is required. If you don't have one, you can create one for free.
Azure CLI	Install the Azure CLI.

Considerations

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

Item	Explanation
Scope	The Eureka Server for Spring component runs in the same environment as the connected container app.
Scaling	The Eureka Server for Spring can’t scale. The scaling properties minReplicas and maxReplicas are both set to 1.
Resources	The container resource allocation for Eureka Server for Spring is fixed. The number of the CPU cores is 0.5, and the memory size is 1Gi.
Pricing	The Eureka Server for Spring billing falls under consumption-based pricing. Resources consumed by managed Java components are billed at the active/idle rates. You can delete components that are no longer in use to stop billing.
Binding	Container apps connect to a Eureka Server for Spring component via a binding. The bindings inject configurations into container app environment variables. Once a binding is established, the container app can read the configuration values from environment variables and connect to the Eureka Server for Spring.

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 EUREKA_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.
   EUREKA_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
   

Create 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 $EUREKA_COMPONENT_NAME
   

2. Optional: 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 $EUREKA_COMPONENT_NAME 
     --configuration eureka.server.renewal-percent-threshold=0.85 eureka.server.eviction-interval-timer-in-ms=10000
   

Bind your container app to the Eureka Server for Spring Java component

1. 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 $EUREKA_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.

View the application through a dashboard

Important

To view the dashboard, you need to have at least the Microsoft.App/managedEnvironments/write role assigned to your account on the managed environment resource. You can either explicitly assign Owner or Contributor role on the resource or follow the steps to create a custom role definition and assign it to your account.

1. Create the custom role definition.

   az role definition create --role-definition '{
       "Name": "<YOUR_ROLE_NAME>",
       "IsCustom": true,
       "Description": "Can access managed Java Component dashboards in managed environments",
       "Actions": [
           "Microsoft.App/managedEnvironments/write"
       ],
       "AssignableScopes": ["/subscriptions/<SUBSCRIPTION_ID>"]
   }'
   

   Make sure to replace placeholder in between the <> brackets in the AssignableScopes value with your subscription ID.

2. Assign the custom role to your account on managed environment resource.

   Get the resource id of the managed environment:

       export ENVIRONMENT_ID=$(az containerapp env show \
        --name $ENVIRONMENT --resource-group $RESOURCE_GROUP \ 
        --query id -o tsv)
   

3. Assign the role to your account.

   Before running this command, replace the placeholder in between the <> brackets with your user or service principal ID.

   az role assignment create \
     --assignee <USER_OR_SERVICE_PRINCIPAL_ID> \
     --role "<ROLE_NAME>" \
     --scope $ENVIRONMENT_ID
   

   Note

   <USER_OR_SERVICE_PRINCIPAL_ID> usually should be the identity that you use to access Azure Portal. <ROLE_NAME> is the name you assigned in step 1.

4. Get the URL of the Eureka Server for Spring dashboard.

   az containerapp env java-component eureka-server-for-spring show \
     --environment $ENVIRONMENT \
     --resource-group $RESOURCE_GROUP \
     --name $EUREKA_COMPONENT_NAME \
     --query properties.ingress.fqdn -o tsv
   

   This command returns the URL you can use to access the Eureka Server for Spring dashboard. Through the dashboard, your container app is also to you as shown in the following screenshot.

   

Optional: Integrate the Eureka Server for Spring and Admin for Spring Java components

If you want to integrate the Eureka Server for Spring and the Admin for Spring Java components, see Integrate the managed Admin for Spring with Eureka Server for Spring.

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

Configure Eureka Server for Spring settings

Related content

• Integrate the managed Admin for Spring with Eureka Server for Spring