Mastering GitHub Actions: A Complete Guide to CI/CD Automation

What is GitHub Actions?

GitHub Actions is a platform which allows you to automate the developer workflows.
Workflows such as :-

1. Continous Delivery
2. Continous Deployement
3. Automation
4. Security

GitHub Actions are Similar to Devops but has much wider coverage in terms of any automation. It allows you to automate any event that happens in the repository and perform certain automated actions.

Core Components of GitHub Actions

GitHub Actions workflow can be triggered when an event occurs into the repository such as pushing change into master, creating pull request against master, creating/publishing your changes. Workflow contains one/multiple actions which can run sequential or parallel on there dedicated machines/containers.

1. Workflow

Workflow is a configurable process that will run one or more jobs. Workflows are often defined into a yaml/yml file which are part of you repository and can be triggered on an event.
All workflows are defined under .github/workflows directory in the repository.
Each workflow can perform different tasks as :-

• Building an application
• Testing an application/changes
• Deploying your changes after every release.
• Adding label in Jira when ticket is opened.

2. Events

Event can be defined as an activity which triggers a workflow inside the repository. Any event can also be triggered at a specific time.

3. Jobs

A job is a set of steps in a workflow that is executed on the same runner. Each step can be a shell script or an action. These steps are executed in order and are dependent on each other. Since all these steps are on same runner data can be shared between them. For Example you can have a step that build your application followed by a step that tests the application.

4. Actions

An action is a custom application for GitHub actions platform that performs a complex but frequently repeated task. It helps in code re-usability of repeated tasks. An action can pull your Git repository from GitHub, set up the correct toolchain for your build environment , or set up the authentication to your cloud provider.
You can also write your own actions, or you can find actions to use in your workflows in the GitHub Marketplace.

5. Runner

A runner is a server that runs your workflows when they’re triggered. Each runner can run a single job at a time. GitHub provides Ubuntu Linux, Microsoft Windows, and macOS runners to run your workflows. Each workflow run executes in a fresh, newly-provisioned virtual machine.

GitHub Actions YAML Workflow Example

Now Lets understand below workflow example . This workflow builds the project Java Project with maven as build tool on certain actions like push/pull into the repository.
name – Defines the workflow name
on – Event on which workflow will be triggered
jobs – set of steps which will be executed for current workflow
runs – Defines the runner on which all steps will run
actions – pre-defined keyword for invoking different actions
steps – dependent steps which are scripts or pre-defined actions.

name: Java CI with Gradle

on:
  push:
    branches: [ "main" ]
  pull request:
    branches: [ "main" ]

jobs:
  build:

    runs-on: ubuntu-latest
    permissions:
      contents: read

    steps:
    - uses: actions/checkout@v4
    - name: Set up JDK 17
      uses: actions/setup-java@v4
      with:
        java-version: '17'
        distribution: 'temurin'

    - name: Setup Gradle
      uses: gradle/actions/setup-gradle@af1da67850ed9a4cedd57bfd976089dd991e2582 # v4.0.0

    - name: Build with Gradle Wrapper
      run: ./gradlew build

    
  dependency-submission:

    runs-on: ubuntu-latest
    permissions:
      contents: write

    steps:
    - uses: actions/checkout@v4
    - name: Set up JDK 17
      uses: actions/setup-java@v4
      with:
        java-version: '17'
        distribution: 'temurin'

    
    - name: Generate and submit dependency graph
      uses: gradle/actions/dependency-submission@af1da67850ed9a4cedd57bfd976089dd991e2582 # v4.0.0

GitHub Actions vs Jenkins Pipelines: Key Differences

Over traditional Jenkins pipelines GitHub Actions provides many advantages

Feature	GitHub Actions	Jenkins Pipeline
Setup	Configuration is in Simple yaml Files.	Configuration is done in Groovy Scripting Language.
Integration	Actions are natively integrated with GitHub.	Jenkins needs hooks and explicit CI/CD Servers.
Flexibility	Everything is event based. Which are flexible in nature.	Flexible but configuration is needed for each and every step.
Maintenance	Managed by dev team as part of application code.	Devops teams are needed to manage.