Publish to GitHub Packages

Use GitHub Actions to publish your project to a Docker image.

Step 1: Create the workflow file

Welcome to "Publish packages"! 👋

First, take a moment to examine the image below. It shows the relationship between continuous integration, continuous delivery and continuous deployment.

Continuous integration (CI) is a practice where developers integrate tested code into a shared branch several times per day. Continuous delivery (CD) is the next phase of continuous integration (CI), where we deploy our changes to the world.

Docker is an engine that allows you to run containers. Containers are packages of software that can run reliably in different environments. Containers include everything needed to run the application. Containers are lightweight in comparison to virtual machines. A Dockerfile is a text document that contains all the commands and instructions necessary to build a Docker Image. A Docker image is an executable package comprised of code, dependencies, libraries, a runtime, environment variables, and configuration files. A Docker container is a runtime instance of a Docker Image.

We'll start by creating the workflow file to publish a Docker image to GitHub Packages.

⌨️ Activity: Create the workflow file

1. Open a new browser tab, and work on the steps in your second tab while you read the instructions in this tab.
2. Navigate to the Code tab.
3. From the main branch dropdown, click on the cd branch.
4. Navigate to the .github/workflows/ folder, then select Add file and click on Create new file.
5. In the Name your file... field, enter publish.yml.
6. Add the following to the publish.yml file:

   name: Publish to Docker
   on:
     push:
       branches:
         - main
   permissions:
     packages: write
   jobs:
     publish:
       runs-on: ubuntu-latest
       steps:
         - name: Checkout
           uses: actions/checkout@v4
         # Add your test steps here if needed...
         - name: Docker meta
           id: meta
           uses: docker/metadata-action@v5
           with:
             images: ghcr.io/YOURNAME/publish-packages/game
             tags: type=sha
         - name: Login to GHCR
           uses: docker/login-action@v3
           with:
             registry: ghcr.io
             username: ${{ github.repository_owner }}
             password: ${{ secrets.GITHUB_TOKEN }}
         - name: Build container
           uses: docker/build-push-action@v5
           with:
             context: .
             push: true
             tags: ${{ steps.meta.outputs.tags }}

7. Replace YOURNAME with your username.
8. Make sure that the image name is unique.
9. Commit your changes.
10. (optional) Create a pull request to view all the changes you'll make throughout this course. Click the Pull Requests tab, click New pull request, set base: main and compare:cd.
11. Wait about 20 seconds then refresh this page (the one you're following instructions from). GitHub Actions will automatically update to the next step.

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