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: List Environment Variables

Introduction

In this lab, you will learn how to display environment variables in Linux, macOS, and Windows operating systems using GitHub Actions.

GitHub Actions allows you to display environment variables in the logs. This can be useful for debugging purposes or to understand the environment in which your code is running. Please note that these environment variables are not secure and should not be used to store sensitive information. Additionally, they are case-sensitive.

Estimated Duration: 20-30 minutes

Instructions

Step 1: Create a YAML Workflow Using the Starter File

  1. Navigate to the Environment Variables List Starter File.

  2. Copy the content of the starter file:

    name: Env Var List

on:
  workflow_dispatch:
  push:
    paths:
      - '.github/workflows/env-var-list.yml'

  3. In your repository, create a new workflow file under .github/workflows and name it env-var-list.yml.

  4. Paste the copied content into the new file.

  5. Commit the workflow file to the main branch.

Step 2: Define Jobs to Display Environment Variables for Different OS

  1. In the env-var-list.yml file, define three jobs: ubuntu, mac, and windows. These jobs will run the same task of displaying environment variables, but on different operating systems.

  2. For each job, use the respective operating system as the runs-on value:

    • For Ubuntu, set runs-on: ubuntu-latest
    • For macOS, set runs-on: macos-latest
    • For Windows, set runs-on: windows-latest

  3. Under each job, add a steps section to display the environment variables. The printenv | sort command will display environment variables for each operating system.

    The workflow should look like this:

    name: Env Var List

on:
  workflow_dispatch:
  push:
    paths:
      - '.github/workflows/env-var-list.yml'

jobs:
  ubuntu:
    runs-on: ubuntu-latest
    steps:
      - name: Display Environment Variables on Ubuntu
        run: printenv | sort

  mac:
    runs-on: macos-latest
    steps:
      - name: Display Environment Variables on MacOS
        run: printenv | sort

  windows:
    runs-on: windows-latest
    steps:
      - name: Display Environment Variables on Windows
        run: printenv | sort
        shell: bash

Step 3: Understanding the Workflow

  1. Name: The name field defines the name of the workflow. In this case, it’s set to Env Var List, which will be displayed in the Actions tab.

  2. Triggers: The on field specifies the event that triggers the workflow. Here, the workflow is triggered either manually via workflow_dispatch or whenever changes are made to the .github/workflows/env-var-list.yml file.

  3. Jobs: This workflow contains three jobs:

    • ubuntu: Runs on ubuntu-latest.
    • mac: Runs on macos-latest.
    • windows: Runs on windows-latest.

  4. Steps: Each job has a steps section where commands are defined to display environment variables using the printenv | sort command. The printenv command lists all environment variables, and sort orders them alphabetically.

Step 4: Commit the Workflow and Trigger It

  1. Commit the changes to the main branch.

  2. Go to your repository on GitHub, and navigate to the Actions tab.

  3. Find the Env Var List workflow on the left sidebar.

  4. Click on the Run workflow button, and select the main branch.

  5. Click the Run workflow button to trigger the workflow.

Step 5: Check the Workflow Run and View Environment Variables

  1. Once the workflow runs, click on the Display Environment Variables job to see the logs for the three operating systems: Ubuntu, macOS, and Windows.

  2. Review the logs to see the environment variables displayed for each operating system. You should notice some common environment variables shared across all operating systems, along with specific environment variables for each OS.

Step 6: Use Matrix Strategy for Parallel Execution (Optional)

  1. You can also use the matrix strategy to run the same job across multiple operating systems in parallel. This is useful for testing your code across different environments simultaneously.

  2. Replace the three individual jobs with a matrix strategy in the workflow file:

    name: Env Var List

on:
  workflow_dispatch:
  push:
    paths:
      - '.github/workflows/env-var-list.yml'

jobs:
  display-environment-variables:
    strategy:
      matrix:
        os: [ubuntu-latest, macos-latest, windows-latest]
    runs-on: $
    steps:
      - name: Display Environment Variables
        run: printenv | sort
        shell: bash

  3. Commit the changes and rerun the workflow.

Summary

Congratulations! You have successfully created a workflow to display environment variables on Ubuntu, macOS, and Windows using GitHub Actions. You have also learned how to use the matrix strategy to run the same job across multiple operating systems in parallel.

Additional Resources