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Developing cloud native microservice applications with the Eclipse MicroProfile application stack

duration 40 minutes

What you’ll learn

You’ll learn how to create and run a simple cloud native microservice based on the Eclipse MicroProfile application stack. You’ll learn how to configure your development environment, update the microservice that you created and deploy it to Kubernetes or serverless. Deployment to serverless is optional depending on whether you want to Scale to Zero.

The Eclipse MicroProfile application stack enables the development and optimization of microservices. With application stacks, developers don’t need to manage full software development stacks or be experts on underlying container technologies or Kubernetes. Application stacks are customized for specific enterprises to incorporate their company standards and technology choices.

Applications in this guide are written based on the Eclipse MicroProfile API specifications, built and run with the Open Liberty runtime, and deployed to Kubernetes through a modern DevOps toolchain that is triggered in Git.

Prerequisites

  • Docker must be installed.
  • Appsody must be installed.
  • Optional: If your organisation has customized application stacks, you need the URL that points to the index.yaml file for the stack hub.
  • Optional: If you are testing multiple microservices together, you must have access to a local Kubernetes cluster for local development. If you are using Docker Desktop, you can enable Kubernetes from the menu by selecting Preferences -> Kubernetes -> Enable Kubernetes. Other options include Minishift or Minikube. If you want to use remote cluster development, use Codewind.

Getting started

Configuring your development environment

To check the repositories that you can already access, run the following command:

appsody repo list

You see output similar to the following example:

NAME        URL
*incubator https://github.com/appsody/stacks/releases/latest/download/incubator-index.yaml

Next, run the following command to add the URL for your stack hub index file:

appsody repo add <my-org-stack> <URL>

where <my-org-stack> is the repository name for your stack hub and <URL> is the URL for your stack hub index file.

Note: If you do not have a stack hub that contains customized, pre-configured application stacks, you can skip to Initializing your project and develop your app based on the public application stack for Eclipse MicroProfile.

Check the repositories again by running appsody repo list to see that your stack hub was added. In the following examples, the stack hub is called acme-stacks and the URL is https://github.com/acme.inc/stacks/index.yaml:

NAME        URL
*incubator https://github.com/appsody/stacks/releases/latest/download/incubator-index.yaml
acme-stacks https://github.com/acme.inc/stacks/index.yaml

In this example, the asterisk (*) shows that incubator is the default repository. Run the following command to set acme-stacks as the default repository:

appsody repo set-default acme-stacks

Check the available repositories again by running appsody repo list to see that the default is updated:

NAME        URL
incubator https://github.com/appsody/stacks/releases/latest/download/incubator-index.yaml
*acme-stacks https://github.com/acme.inc/stacks/index.yaml

Recommendation: To avoid initializing projects that are based on the public application stacks, it’s best to remove incubator from the list. Run the following command to remove the incubator repository:

appsody repo remove incubator

Check the available repositories again by running appsody repo list to see that incubator is removed:

NAME     	URL
*acme-stacks https://github.com/acme.inc/stacks/index.yaml

Your development environment is now configured to use your customized application stacks. Next, you need to initialize your project.

Initializing your project

First, create a directory that will contain the project:

mkdir -p ~/projects/simple-microprofile
cd ~/projects/simple-microprofile

Run the following command to initialize the project with the CLI:

appsody init java-microprofile

The output from the command varies depending on whether you have an installation of Java and Maven on your system. If Java and Maven are installed on your system, you see an output similar to the following example:

[InitScript] [INFO] -------------------< dev.appsody:java-microprofile >--------------------
[InitScript] [INFO] Building java-microprofile 0.2.11
[InitScript] [INFO] --------------------------------[ pom ]---------------------------------
[InitScript] [INFO]
[InitScript] [INFO] --- maven-enforcer-plugin:3.0.0-M2:enforce (enforce-versions) @ java-microprofile ---
[InitScript] [INFO] Skipping Rule Enforcement.
[InitScript] [INFO]
[InitScript] [INFO] --- maven-install-plugin:2.4:install (default-install) @ java-microprofile ---
[InitScript] [INFO] Installing /Users/myuser/projects/simple-microprofile/.appsody_init/pom.xml to /Users/myuser/.m2/repository/dev/appsody/java-microprofile/0.2.11/java-microprofile-0.2.11.pom
[InitScript] [INFO] ------------------------------------------------------------------------
[InitScript] [INFO] BUILD SUCCESS
[InitScript] [INFO] ------------------------------------------------------------------------
[InitScript] [INFO] Total time:  0.648 s
[InitScript] [INFO] Finished at: 2019-09-13T10:17:55+01:00
[InitScript] [INFO] ------------------------------------------------------------------------
Successfully initialized Appsody project

If Java and Maven are not installed on your system, you see an output similar to the following example:

[InitScript] Unable to find any JVMs matching version "(null)".
[InitScript] No Java runtime present, try --request to install.
[InitScript] Unable to find a $JAVA_HOME at "/usr", continuing with system-provided Java...
[InitScript] No Java runtime present, requesting install.
[Warning] The stack init script failed: exit status 1
[Warning] Your local IDE may not build properly, but the Appsody container should still work.
[Warning] To try again, resolve the issue then run `appsody init` with no arguments.

Your project is now initialized.

Understanding the project layout

For context, the following image displays the structure of the project that you’re working on:

Project structure

It contains the following artifacts:

  • StarterApplication.java, a JAX-RS Application class
  • server.xml, an Open Liberty server configuration file
  • index.html, a static HTML file
  • pom.xml, a project build file

Running the development environment

Run the following command to start the development environment:

appsody run

The CLI launches a local Docker image that contains an Open Liberty server that hosts the microservice. After some time, you see a message similar to the following example:

[Container] [INFO] [AUDIT   ] CWWKF0011I: The defaultServer server is ready to run a smarter planet. The defaultServer server started in 20.235 seconds.

This message indicates that the server is started and you are ready to begin developing your application.

Creating and updating the application

Now you can create your business logic. Typically, you put your business logic in a JAX-RS resource. First, you need to add a REST endpoint.

Create a StarterResource.java class in the src/main/java/dev/appsody/starter directory. Open the file, populate it with the following code, and save it:

package dev.appsody.starter;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
@Path("/resource")
public class StarterResource {
    @GET
    public String getRequest() {
        return "StarterResource response";
    }
}

After you save, the source compiles and the application updates. You see messages similar to the following example:

[Container] [INFO] [AUDIT   ] CWWKT0017I: Web application removed (default_host): http://85862d8696be:9080/
[Container] [INFO] [AUDIT   ] CWWKZ0009I: The application starter-app has stopped successfully.
[Container] [INFO] [AUDIT   ] CWWKT0016I: Web application available (default_host): http://85862d8696be:9080/
[Container] [INFO] [AUDIT   ] CWWKZ0003I: The application starter-app updated in 0.988 seconds.

The resource that you just added is available at the starter/resource URL path. Go to the http://localhost:9080/starter/resource URL to see the following resource response:

StarterResource response

Try changing the message in the StarterResource.java file, saving, and refreshing the page. You’ll see that it takes only a few seconds for the change to take effect.

Use Ctrl+C to stop the development environment, or run the command appsody stop from another terminal.

Testing the application

If you are building an application that is composed of microservices, you need to test within the context of the overall system. First, test your application and perform unit testing in isolation. To test the application as part of the system, deploy the system and then the new application.

You can choose how you want to deploy the system and application. If you have adequate CPU and memory to run MiniShift, the application, and the associated services, then you can deploy the application on a local Kubernetes that is running on your computer. Alternatively, you can enable Docker Desktop for Kubernetes, which is described in the Prerequisites section of the guide.

You can also deploy the system, application, and the associated services in a private namespace on a development cluster. From this private namespace, you can commit the microservices in Git repositories and deploy them through a DevOps pipeline, not directly to Kubernetes.

Testing locally on Kubernetes

After you finish writing your application code, the Appsody CLI makes it easy to deploy directly to a Kubernetes cluster for further local testing. The ability to deploy directly to a Kubernetes cluster is valuable when you want to test multiple microservices together or test with services that the application requires.

Ensure that your kubectl command is configured with cluster details, and run the following command to deploy your application:

appsody deploy

This command builds a new Docker image that is optimized for production deployment and deploys the image to your local Kubernetes cluster. After some time you see a message similar to the following example:

Deployed project running at http://localhost:30262

Run the following command to check the status of the application pods:

kubectl get pods

You see an output similar to the following example:

NAME                                  READY    STATUS   RESTARTS   AGE
appsody-operator-859b97bb98-htpgw      1/1     Running   0         3m2s
simple-microprofile-77d6868765-xkcpk   1/1     Running   0         31s

The pod that is related to your deployed application is similar to the following pod:

simple-microprofile-77d6868765-xkcpk   1/1     Running   0         31s

After the simple-microprofile pod starts, go to the URL that was returned after you ran the appsody deploy command, and you see the splash screen. To see the response from your application, point your browser to <URL_STRING>/starter/resource, where <URL_STRING> is the URL that was returned. For example, the http://localhost:30262 URL was returned in the previous example. Go to the http://localhost:30262/starter/resource URL to see the deployed application response.

Use the following command to stop the deployed application:

appsody deploy delete

After you run this command, and the deployment is deleted, you see the following message:

Deployment deleted

Testing with serverless

You can choose to test an application that is deployed with serverless to take advantage of Scale to Zero. Not all applications can be written to effectively take advantage of Scale to Zero. The Kabanero operator-based installation configures serverless on the Kubernetes cluster. Because of the resources that are required to run serverless and its dependencies, testing locally can be difficult. Publish to Kubernetes by using pipelines that are described later in the guide. Your operations team can configure the pipelines so that serverless is enabled for deployment.

Publishing to Kubernetes by using pipelines

After you develop and test your application in your local environment, it’s time to publish it to your enterprise’s pipeline. From your enterprise’s pipeline, you can deploy the application to the appropriate Kubernetes cluster for staging or production. Complete this process in Git.

When Kabanero is installed, deploying applications to a Kubernetes cluster always occurs through the DevOps pipeline that is triggered in Git. Using DevOps pipelines to deploy applications ensures that developers can focus on application code, not on containers or Kubernetes infrastructure. From an enterprise perspective, this deployment process ensures that both the container image build and the deployment to Kubernetes or Knative happen in a secure and consistent way that meets company standards.

To deliver your application to the pipeline, push the project to the pre-configured Git repository that has a configured webhook. This configured webhook triggers the enterprise build and deploy pipeline.

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