GitHub Actions Tutorial - Basic Concepts and CI/CD Pipeline with Docker

Introduction

In this tutorial, we will explore GitHub Actions, a powerful tool for automating workflows, particularly for continuous integration and continuous deployment (CI/CD) processes. We will cover basic concepts, practical use cases, and walk through a hands-on demo that includes building a Docker image and pushing it to a private Docker repository. This guide is designed to help developers of all levels understand and implement GitHub Actions in their projects.

Step 1: Understand GitHub Actions

• GitHub Actions is a CI/CD tool that helps automate the development workflow directly within GitHub.
• It allows you to create workflows, which are automated processes triggered by specific events in your GitHub repository, such as:
  • Code pushes
  • Pull requests
  • Issues

Step 2: Identify Developer Workflows

• Developer workflows are tasks that can be automated using GitHub Actions, including:
  • Running tests before merging code.
  • Building and deploying applications automatically.
  • Sending notifications upon certain events.
• Use cases for GitHub Actions might include:
  • Automating code linting and formatting.
  • Deploying applications to cloud services after a successful build.

Step 3: Explore Basic Concepts of GitHub Actions

• Key components of GitHub Actions include:
  • GitHub Events: Triggers that start the workflow.
  • Actions: Reusable units of code that perform a specific task.
  • Workflows: A series of actions defined in YAML files that automate tasks.

Step 4: Learn About CI/CD with GitHub Actions

• Continuous Integration (CI) ensures that code changes are automatically tested and integrated into the main branch.
• Continuous Deployment (CD) automates the release of code to production after passing tests.
• Benefits of using GitHub Actions for CI/CD:
  • Seamless integration with GitHub repositories.
  • Ability to define complex workflows easily.
  • Large marketplace of pre-built actions to expedite development.

Step 5: Create a CI Workflow

• Start by setting up a new GitHub Actions workflow:
  • Navigate to your GitHub repository.
  • Go to the "Actions" tab and select "Set up a workflow yourself."
• Define the workflow in a YAML file with the following structure:

  name: CI Workflow
  on:
    push:
      branches:
        - main
  jobs:
    build:
      runs-on: ubuntu-latest
      steps:
        - name: Checkout code
          uses: actions/checkout@v2
        - name: Set up JDK
          uses: actions/setup-java@v2
          with:
            java-version: '11'
        - name: Build with Gradle
          run: ./gradlew build
  

Step 6: Understand Workflow File Syntax

• The workflow file uses YAML syntax to define:
  • Triggers: Events that start the workflow.
  • Jobs: A series of steps that run in parallel or sequentially.
  • Steps: Individual tasks within a job, such as checking out code or running a build command.

Step 7: Execute the Workflow Code

• GitHub Actions runs in a containerized environment called a runner.
• When a workflow is triggered, it executes the defined jobs and steps within these runners, providing a consistent environment for builds and tests.

Step 8: Build and Push Docker Image

• To build a Docker image and push it to a private Docker repository, add the following steps to your workflow:

        - name: Log in to DockerHub
          uses: docker/login-action@v1
          with:
            username: ${{ secrets.DOCKER_USERNAME }}
            password: ${{ secrets.DOCKER_PASSWORD }}
        - name: Build Docker Image
          run: docker build . -t my-image:latest
        - name: Push Docker Image
          run: docker push my-image:latest
  

• Ensure you have added your DockerHub credentials as secrets in your GitHub repository.

Conclusion

In this tutorial, we've covered the essentials of GitHub Actions, including its purpose, components, and practical applications for CI/CD. You learned how to set up a CI workflow, understand workflow syntax, and build and push a Docker image. As a next step, consider exploring more complex workflows or integrating additional actions from the GitHub Marketplace to further enhance your automation processes.