After working with GitHub Actions in my home lab, I want to share what I learned about the basics. This is the stuff I wish someone explained to me when I started.<\/p>\n
GitHub Actions is a CI\/CD tool built into GitHub. You write YAML files that tell GitHub what to do when something happens in your repository like when you push code, open a PR, or click a button.<\/p>\n
Every GitHub Actions workflow has 3 main parts:<\/p>\n
A workflow is a YAML file stored in .github\/workflows\/ in your repository. Here’s my first workflow:<\/p>\n
name: 01 - Building Blocks\non: push\n\njobs:\n echo-hello:\n runs-on: ubuntu-latest\n steps:\n - name: say hello\n run: echo \"Hello World!\"<\/code><\/pre>\nThis workflow runs every time I push code to any branch.<\/p>\n
2. Jobs<\/h3>\n
Jobs are groups of steps that run on the same runner. By default, jobs run in parallel, but you can make them run one after another.<\/p>\n
Here’s something I learned the hard way if one step fails, the rest of the steps in that job won’t run:<\/p>\n
jobs:\n echo-goodbye:\n runs-on: ubuntu-latest\n steps:\n - name: Failed Step\n run: |\n echo \"I will fail\"\n exit 1\n - name: say goodbye\n run: echo \"Good bye\" # This never runs!<\/code><\/pre>\nThe “say goodbye” step never executes because the previous step exits with code 1.<\/p>\n
3. Steps<\/h3>\n
Steps are individual tasks in a job. They can run commands or use pre-built actions from the marketplace.<\/p>\n
steps:\n - name: Say hello\n run: echo \"Hello, world!\"<\/code><\/pre>\nWorkflow Events: When Should Things Run?<\/h3>\n
The on: field tells GitHub when to trigger your workflow. I use three main types:<\/p>\n
Push Events<\/h3>\n
Runs when you push code:<\/p>\n
on: push<\/code><\/pre>\nPull Request Events<\/h3>\n
Runs when someone opens or updates a PR:<\/p>\n
on: pull_request<\/code><\/pre>\nManual Trigger<\/h3>\n
This is super useful for testing. You get a “Run workflow” button in GitHub UI:<\/p>\n
on: workflow_dispatch<\/code><\/pre>\nRunners: Where Does Code Run?<\/h3>\n
Runners are the machines that execute your jobs. GitHub provides three types:<\/p>\n
jobs:\n ubuntu-echo:\n runs-on: ubuntu-latest\n steps:\n - name: Show OS\n run: |\n echo \"This job is running on an Ubuntu runner.\"\n echo \"Runner OS: $RUNNER_OS\"\n windows-echo:\n runs-on: windows-latest\n steps:\n - name: Show OS\n shell: bash # Important for Windows!\n run: |\n echo \"This job is running on a Windows runner.\"\n echo \"Runner OS: $RUNNER_OS\"\n mac-echo:\n runs-on: macos-latest\n steps:\n - name: Show OS\n run: |\n echo \"This job is running on a MacOS runner.\"\n echo \"Runner OS: $RUNNER_OS\"<\/code><\/pre>\nImportant:<\/strong> On Windows runners, you need to specify shell: bash if you want to use bash commands. Otherwise it uses PowerShell by default.<\/p>\nUsing Pre-built Actions<\/h3>\n
You don’t have to write everything from scratch. GitHub Marketplace has thousands of actions. Here’s a real example from my React app workflow:<\/p>\n
jobs:\n build:\n runs-on: ubuntu-latest\n defaults:\n run:\n working-directory: 04-using-actions\/react-app\n steps:\n - name: Checkout Code\n uses: actions\/checkout@v4\n - name: Setup Node\n uses: actions\/setup-node@v4\n with:\n node-version: '20.x'\n - name: Install Dependencies\n run: npm ci\n - name: Run Unit Tests\n run: npm run test<\/code><\/pre>\nThe uses: keyword tells GitHub to run an action from the marketplace. The with: section passes parameters to that action.<\/p>\n
Context: Getting Information About Your Workflow<\/h3>\n
GitHub gives you a lot of information through the github context. You can access it using ${{ }} syntax:<\/p>\n
steps:\n - name: Display information\n run: |\n echo \"Event Name: ${{ github.event_name }}\"\n echo \"Ref: ${{ github.ref }}\"\n echo \"SHA: ${{ github.sha }}\"\n echo \"Actor: ${{ github.actor }}\"\n echo \"Workflow: ${{ github.workflow }}\"\n echo \"Run ID: ${{ github.run_id }}\"\n echo \"Run number: ${{ github.run_number }}\"<\/code><\/pre>\nThis is useful for debugging or creating unique identifiers for your builds.<\/p>\n
What I Learned<\/h3>\n- Start small:<\/strong> My first workflow was just echo commands. Then I added real steps one by one.<\/li>
- Use workflow_dispatch:<\/strong> Adding manual triggers makes testing so much easier. You don’t have to push code just to test your workflow.<\/li>
- Check the logs:<\/strong> When something fails, GitHub shows you exactly which step failed and why. The logs are your best friend.<\/li>
- Runners cost money:<\/strong> GitHub gives you free minutes, but they run out. Ubuntu runners are cheapest. Windows and macOS cost more.<\/li>
- YAML is sensitive:<\/strong> Indentation matters. A lot. One extra space and your workflow won’t work.<\/li><\/ol>\n
My Setup<\/h3>\n
I’m running these workflows in my home lab where I practice DevOps concepts. All my code is on GitHub, and I use these workflows to automate testing and deployment.<\/p>","protected":false},"excerpt":{"rendered":"
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