GitHub Actions Workshop

Master GitHub Actions with hands-on labs and exercises. Learn how to automate workflows, run tests, deploy applications, and more using GitHub's powerful automation platform. This repository has everything you need to get started with continuous integration and continuous deployment.

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Lab: Introduction to Reusable Workflows

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Objective

In this lab, you will learn how to create and use reusable workflows in GitHub Actions. A reusable workflow enables modularity by defining common steps in one workflow that can be invoked by other workflows.

This lab covers:

1. Creating a reusable workflow.
2. Defining a caller workflow to invoke the reusable workflow.

Duration: 20-30 minutes

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Prerequisites

1. GitHub Repository: Ensure you have access to a repository where you can create workflows.
2. Basic Knowledge of YAML: Familiarity with GitHub Actions workflow syntax is beneficial.

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Instructions

Step 1: Create a Reusable Workflow

1. Navigate to Your Repository:

   • Open your GitHub repository in Visual Studio Code or your preferred IDE.

2. Create the Workflow File:

   • In the .github/workflows directory, create a new file named reusable-workflow-echo.yml.

3. Define the Reusable Workflow:

   • Add the following YAML code:

     name: Reusable Workflow Echo
     on:
       workflow_call:
         inputs:
           my-input:
             required: true
             type: string
     jobs:
       echo:
         runs-on: ubuntu-latest
         steps:
           - name: Echo input
             run: echo $
     

   Explanation

   • workflow_call: Specifies that this is a reusable workflow.
   • inputs: The my-input parameter is required and will accept a string.
   • Job echo: Runs on an Ubuntu environment and echoes the provided input.

4. Commit the Workflow:

   • Save and commit the file:

     git add .github/workflows/reusable-workflow-echo.yml
     git commit -m "Add reusable workflow"
     git push
     

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Step 2: Create a Caller Workflow

1. Create the Workflow File:

   • In the .github/workflows directory, create another file named reusable-workflow-echo-caller.yml.

2. Define the Caller Workflow:

   • Add the following YAML code:

     name: Reusable Workflow Echo Caller
     
     on:
       workflow_dispatch:
       push:
         paths:
           - '.github/workflows/reusable-workflow-echo-caller.yml'
     jobs:
       call:
         uses: ./.github/workflows/reusable-workflow-echo.yml
         with:
           my-input: 'Hello, world!'
     

   Explanation

   • workflow_dispatch: Allows manual execution of this workflow.
   • push: Automatically triggers the workflow if changes are made to the caller workflow file.
   • uses: Calls the reusable workflow reusable-workflow-echo.yml.
   • with: Supplies the required input my-input with the value 'Hello, world!'.

3. Commit the Caller Workflow:

   • Save and commit the file:

     git add .github/workflows/reusable-workflow-echo-caller.yml
     git commit -m "Add reusable workflow caller"
     git push
     

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Step 3: Trigger and Verify the Workflows

1. Manually Trigger the Caller Workflow:

   • Navigate to the Actions tab in your GitHub repository.
   • Select the Reusable Workflow Echo Caller workflow.
   • Click Run workflow to manually trigger it.

2. View the Output:

   • Open the workflow run details.
   • Look for the Echo input step under the call job.

   • Verify that the output is:

     Hello, world!
     

3. Modify the Input Parameter:

   • Edit the reusable-workflow-echo-caller.yml file:

     with:
       my-input: 'Reusable workflows are powerful!'
     

   • Commit and push the changes:

     git add .github/workflows/reusable-workflow-echo-caller.yml
     git commit -m "Update input parameter"
     git push
     

4. Re-trigger the Workflow:

   • Navigate to the Actions tab and rerun the Reusable Workflow Echo Caller workflow.
   • Verify the new input value is echoed in the logs.

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Summary

In this lab, you have learned how to:

• Create a reusable workflow with input parameters.
• Call the reusable workflow using a caller workflow.
• Pass dynamic parameters from the caller to the reusable workflow.

Reusable workflows help improve the modularity, maintainability, and scalability of your CI/CD pipelines.

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Additional Resources

• Reusable Workflows in GitHub Actions
• GitHub Actions Workflow Syntax