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Developing microservice applications with the CLI

duration 20 minutes

What you’ll learn

You will learn how to use the Command Line Interface (CLI) to configure your local development environment to access customized application stacks. You will then learn how to use the CLI to create, run, test, and debug an application built from an application stack. Finally, you will learn how to build a deployment image that is ready to run in a Kubernetes or serverless environment.


Getting started

Application stacks enable applications to be built and tested inside a container. When built, the container can be deployed into a Kubernetes or serverless environment.

When you install Appsody, the default configuration references the public open source repositories, which contain all the available application stacks from the Appsody project. Although you can use the content in a public repository, an organization typically customizes a set of application stacks to suit their own requirements. To develop microservice applications from customized application stacks, you must modify your local configuration to point to these stacks before creating a project.

Discovering repositories and stacks

CLI command: appsody repo list

To view the current repositories that you have access to, run the appsody repo list command. The asterisk shown in the output indicates the default repository.

NAME            URL

By default, your local development environment can access the incubator and experimental public repositories.

Adding a customized application stack hub

CLI command: appsody repo add <repo-name> <URL>

As a developer, your enterprise architect might provide you with a URL that points to a stack hub, which contains a set of customized application stacks for your organization. The stack hub configuration is contained in a repository and defined by an index.yaml file.

To add this configuration information to your local development environment, use the appsody repo add <repo-name> <URL> command, supplying a name for the repository and the URL that contains the index.yaml file.

In this example, you will add the public Kabanero stack hub, which has the URL

  • Run the following command:
appsody repo add kabanero
  • Check that the repository changes are added successfully by running the appsody repo list command again. The output should be similar to the following example:
NAME          URL

Setting your default repository

CLI command: appsody repo set-default <repo-name>

You can change the default repository by using the appsody repo set-default <repo-name> command.

  • Set kabanero as your default repository by running the following command:
appsody repo set-default kabanero
  • Run appsody repo list again to check that kabanero is now the default repository:
NAME            URL

The asterisk indicates that kabanero is now the default repository.

Viewing the available stacks

CLI command: appsody list <repo-name>

Now that you have set up your repository you can view the available application stacks with the appsody list command. To limit the output to only one repository, specify the repository name. Run the following command to limit the list of available stacks to the kabanero repository:

  • Run the appsody list command:
appsody list kabanero

The output is similar to the following example, which provides detailed information for each stack:

REPO               ID               	VERSION  	TEMPLATES               	DESCRIPTION                                              
kabanero	   java-openliberty 	0.2.11   	*default, kafka         	Eclipse MicroProfile & Jakarta EE on Open Liberty & OpenJ9
           	                 	         	                                using Maven                                                 
kabanero	   java-spring-boot2	0.3.29   	*default, kafka, kotlin 	Spring Boot using OpenJ9 and Maven                          
kabanero	   nodejs           	0.3.6    	*simple                 	Runtime for Node.js applications                            
kabanero	   nodejs-express   	0.4.8    	kafka, scaffold, *simple	Express web framework for Node.js                           
kabanero           quarkus          	0.3.3    	*default, kafka         	Quarkus runtime for running Java applications

In the output you can see multiple application stacks (IDs) in the kabanero repository. Each stack includes a version number, one or more templates (an asterisk (*) indicates the default template), and a description.

Developing an application

CLI command: appsody init <repo-name>/<stack> <template>

When you initialize a project by using the CLI, a containerized development environment is created with a sample application that runs with the technology stack of your choice.

  • Before you create a project, create a directory for it:
mkdir my-project
cd my-project
  • Then, run the appsody init command to set up your project, which downloads the template for your chosen stack. Because you already set kabanero as your default repository in the last section, run the following command to create a nodejs-express project with the default (simple) template:
appsody init nodejs-express

When the initialization completes you should see the following output:

Successfully initialized Appsody project

Running an application

CLI command: appsody run

This command runs a project in a container, where the container is linked to the project source code on the local system. In the previous step, you initialized the nodejs-express stack, which created a project directory that contains a sample app.js application.

  • Run the application now by typing the appsody run command.

  • Navigate to http://localhost:3000 to see the output. NOTE: The URL can be different, depending on the stack, so consult the documentation.

  • Edit app.js so that it outputs something other than Hello from Appsody!. When you save the file, the change is detected and the container is automatically updated.

  • Refresh http://localhost:3000 to see the new message.

Checking the status of your running container

CLI command: appsody ps

To list all the stack-based containers that are running in your local environment, use the appsody ps command. The output provides information about the container ID, name, image, and the status of each container.

  • Run the appsody ps command to see output that is similar to the following example:
CONTAINER ID	NAME            IMAGE                       	STATUS
f20ec098a612	my-project-dev	kabanero/nodejs-express:0.4	Up 8 minutes

Stopping your Appsody container

CLI command: appsody stop --name <container-name>

To stop a container you can either press Ctrl-C in the terminal or use the appsody stop command.

If you have more than one development project open, use the appsody stop --name <container-name> to stop a specific container. Use the appsody ps command to find the name of the container you want to stop.

Testing your application

CLI command: appsody test

The appsody test command runs the test suite for your application in the development container. Each application stack provides a set of generic tests, which verify that the capabilities provided by the stack are working as expected. Typically, these tests check that the endpoints that are created, such as /metrics and /health, are available. In addition, you can define further tests for your application in your project /test folder.

In earlier sections of this guide you created a nodejs-express project with the default (simple) template, which provides a sample test as a starting point. Take a look at the sample test in the my-project/test/test.js file. You can update this file to suit your test requirements.

Now try running the appsody test command for your project. The results from the test suite are included in the output.

The testing uses constructs that are familiar to the programming language or framework on which the stack is based. You can add your own tests or switch to your preferred testing framework. Node.js application stacks use the Mocha test framework as default. If you want to use a different test framework, update the npm test command in your project package.json file.

To stop the container that is running the tests, you can quit by pressing Ctrl-C or running appsody stop in the terminal.

Debugging your application

CLI command: appsody debug

The appsody debug command starts the development container with a debugger enabled. Typically, your IDE can connect to the debug port used by an application stack. You can then set breakpoints and step through your code as it runs in the container.

  • Run the appsody debug command. The output shows the exposed debug port. For the nodejs-express stack, the debug port is 9229, by default. The debug port varies, depending on your application stack, so check the documentation.

  • To stop the container running in debug mode, you can quit by pressing Ctrl-C or running appsody stop in the terminal.

Building your application for deployment

CLI command: appsody build

The appsody build command generates an image for deployment. This image differs slightly from the development image that is generated by the CLI for running, testing, and debugging your application.

  • Run the appsody build command. This command completes the following two actions:

    • Extracts your code and other artifacts, including a new Dockerfile, which are required to build the deployment image from the development image. These files are saved to the ~/.appsody/extract directory.

    • Runs a build against the Dockerfile that was extracted in the previous step to produce a deployment image in your local container registry. If you want to give your image a name, specify the -t <tag> parameter, for example appsody build -t my-own-project. If you run appsody build with no parameters, the image is given the same name as your project.

  • Now create a deployment image called my-first-app for your application by running the following command:

appsody build -t my-first-app

NOTE: If your project name includes uppercase characters, these are converted to lowercase characters in the image name because uppercase characters are not accepted in image tags. Also, if your project directory includes underscore characters, these are converted to dashes (-), because certain areas of Kubernetes are not tolerant of underscore characters.

When the build finishes, check that your image is available by running the docker images command. You should see your image at the beginning of the list, in a similar format to the following output:

REPOSITORY                                                                TAG                           IMAGE ID            CREATED             SIZE
my-first-app                                                              latest                        1a957433be51        4 seconds ago       945MB

Your deployment image can now be used to run your containerized application in a Kubernetes or serverless environment.

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