Use Appsody to develop an application locally, containerize it, and migrate it to Docker Hub

In this tutorial, I show you how to use a new open source project, Appsody, to create an application locally and then build and deploy that application to a Docker Hub so you can use it on any cloud or platform that supports Docker images. After completing this tutorial, you will understand how Appsody enables you to containerize a Node.js Express application without having to be an expert in container technology.

Prerequisites

To complete the steps in this tutorial, you need to:

1. Install Docker on your local machine.
2. Install Visual Studio Code for local development.
3. Install Appsody. Follow these instructions for your operating system.

Steps

1. Clone the application
2. Open the application in Visual Studio Code
3. Initialize Appsody in your project
4. Change the application on your local machine
5. Build and deploy the application to Docker Hub

1. Clone the application

This tutorial uses a sample application you can find in this GitHub repo. The first step is to clone the project.

1. Open your terminal and change your directory by using the cd downloads command. (Or any other directory in which you want to clone the project).
2. Run command git clone https://github.com/mahsankhaan/appsody.git.

2. Open the application in Visual Studio Code

To open the application in VS Code, follow these steps:

1. Open Visual Code Studio.
2. From the Welcome page, select File from the navigation bar and, under that, select Open.
3. A popup window will appear. Navigate to where the Appsody folder was downloaded. In our case, the Appsody folder is in the Downloads repositry).
4. Select the folder and click Open.

Now you should be able to see all the files in VS code.

3. Initialize Appsody in your project

Before initializing Appsody, let's review some key Appsody terms:

• Stack: Appsody uses preconfigured technology stacks for popular runtimes and frameworks, such as Java with Eclipse and Node.js with Express.
• Template: These templates offer a starting point for application development. You can customize a project template with your standards and specifications and share them across teams.
• Repo: Depending on the content of the stack, repos are categorized as stable, which means they've been tested and support all Appsody commands, incubator, which means they're being actively being worked on, or experimental which means they're not being actively worked on.

For more, check out the documentation.

Steps to initialize appsody:

1. Open Visual Studio Code. Use CTRL + Shift + ` to access terminal from your VS code and execute the following commands:

2. From the terminal, enter appsody list to view all available Appsody stacks.

3. Review the list of stacks and find one that closely resembles your existing project.

   The sample application in this tutorial is a Node.js Expres app, so we select that.

   

4. Run the appsody init nodejs-express none command to initialize a template.

NOTE We use "none” in the above command because we are initializing Appsody in an existing project. If you want to initialize from start, then use *appsody init nodejs-express simple which creates a Node.js application template with Appsody.

5. Once the template is successfully initialized, you should see the ‘.appsody-config.yml’ file name in the left navigation of your VS Code editor.

4. Change the application on your local machine

When you initialize a source code project with Appsody, you get a local Appsody development container. Use the ‘appsody run’ command to start the development container in ‘run’ mode in the foreground. Appsody watches your local project directory for file changes and updates the application to reflect code changes as you develop.

1. Open your web browser and add the URL localhost:3000. 3000 is the default port to run a Node.js application.
2. You should see output that says "App started on Port 3000" which tells you that your application is up and running as a container.

Make some changes to your code and check for updates. Here are some minor changes you can make:

1. In VS Code, go to Views -> Login.ejs (this is the login front-end page).
2. There is a label for “username" in lower case. Make it upper case “USERNAME”.
3. Save the updated file using CTRL+S.
4. Again, visit the URL localhost:3000 and check for updates.

5. Build and deploy the application to Docker Hub

After you finished creating your Appsody application on your local system, you can deploy it to a container platform. The following steps show you how to containerize it and upload it to Docker Hub. From there, you can easily deploy it to a suitable runtime infrastructure such as IBM Cloud.

1. Use the ‘appsody build’ command to generate a deployable Docker image.
2. After your image is successfully built, you should see the app-deploy.yml file in the left navigation.
3. Run the docker images command to see your image on your local machine.

Create a repository on Docker Hub:

1. Now, log into Docker Hub. if you don’t have an account, make it from Docker-Signup
2. On the top of your dashboard,select “Create repository” .
3. In the name field, enter appsody.
4. In the description field, enter App modernization using appsody.
5. At the bottom of the page, select the Create button.

You should see that a registry is created with the username/appsody. For instance, mine is ahsanoffical/appsody. You can use this registry to push and pull the images.

Push your image to Docker Hub:

1. Open your VS Code terminal.
2. Run docker login command. You should see the newly created image name is testing-appsody.
3. Run the command docker tag testing-appsody ahsanoffical/appsody:testing.
4. Run the command docker push ahsanoffical/appsody:testing
5. Check that your local image is successfully uploaded to your Docker Registry.

6. In the future, you can pull the image anywhere by using the docker pull ahsanoffical/appsody:testing command.

   

   Conclusion

In this tutorial, you learned how to integrate Appsody in VS Code to minimize the local development workload, containerize the application and upload to Docker Hub to prepare it for deployment to any cloud platform that supports Docker images.