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How to Build Your First CI/CD Pipeline Using GitHub Actions

Published by dbxquad on May 16, 2023

If you’re looking to dip your toes into the world of CI/CD (that’s Continuous Integration/Continuous Deployment for non-jargon fans), you’ve come to the right place. Today, we’ll create your first CI/CD pipeline using GitHub Actions—like a boss—to automate tests on a very simple Python script. Don’t worry; we’re taking this slow, with a light-hearted approach and simple explanations. Buckle up, it’s time to automate all the boring parts!

What Do You Need Before We Start?

  • A GitHub account. (If you don’t have one yet, seriously, go make one—it’s free and gets you access to lots of cool stuff like, well, this tutorial!)
  • Your trusty WSL (Windows Subsystem for Linux) Ubuntu environment.
  • A Python script. Any Python script. Even if it’s just print('Hello, world!'). We’re keeping it simple today.

Step 1: Create Your Repository

Let’s kick things off by creating a GitHub repository.

  1. Log into GitHub and click the “New” button in the Repositories section.
  2. Name your repository something awesome like ci-cd-python-pipeline. You can make it public or private; up to you. Don’t forget to check the box that says “Add a README file”—it makes life easier.
  3. Click “Create repository.” Bam! You now have a home for your future CI/CD masterpiece.

Step 2: Add Your Python Script

Time to bring some Python power.

  1. In your new repository, click the ‘Add file’ button, then select ‘Create new file’.
  2. Name your file something like hello.py (classic).
  3. Paste in your Python code, e.g. :
def my_function():
    return "Hey, this is my first CI/CD!"

if __name__ == "__main__":
    print(my_function())
  1. Commit your new file to the main branch by clicking “Commit Changes…”. A popup window will require you to enter a commit message—just add a brief description like ‘Add hello.py’. Congratulations! You’re now an official Python script owner.

Step 3: Let’s Get Action-Packed with GitHub Actions

Now, here comes the fun part—setting up GitHub Actions for some automation magic!

  1. Click on the Actions tab in your repository. GitHub will suggest some templates, but we’re making our own!
  1. Click Set up a workflow yourself.
  2. Name your workflow file .github/workflows/python-ci.yml. The path matters, so make sure it’s exactly like that.

Step 4: Write the Workflow

Time to tell GitHub what to do. Don’t worry, it listens well.

Here’s the code you’ll paste in to create a workflow that runs whenever you push code to your repository:

name: Python CI Pipeline

on:
  push:
    branches:
      - main
  pull_request:
    branches:
      - main

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
    - name: Checkout repository
      uses: actions/checkout@v2

    - name: Set up Python
      uses: actions/setup-python@v2
      with:
        python-version: '3.x'

    - name: Install dependencies
      run: |
        python -m pip install --upgrade pip
        if [ -f requirements.txt ]; then pip install -r requirements.txt; fi

    - name: Run Python script
      run: |
        python hello.py

What’s Happening Here?

  • name: We call our workflow Python CI Pipeline. Feel free to get creative here, like Deploy-o-Tron 3000.
  • on: This workflow will trigger whenever you push to the main branch or create a pull request to it.
  • jobs: We define the job called build.
  • runs-on: This job will run on ubuntu-latest, which is basically a virtual machine that GitHub is nice enough to lend us.
  • steps: These are the individual commands we’ll run.
    • First, we checkout the code (so GitHub knows what files to work with).
    • We set up Python.
    • Next, we install dependencies (if any are needed—for now, there aren’t any).
    • Lastly, we run the script to ensure it works, and then run tests using pytest to verify everything behaves as expected.

Step 5: Push Your Changes and Watch the Magic Happen

  1. Save the workflow file by clicking Commit changes…. After clicking this button, a popup window will require you to enter a commit message—just add a brief description like ‘Add CI workflow’.
  2. If everything goes smoothly, you’ll see a big green checkmark in the Actions tab indicating that your workflow ran successfully. If there’s an issue, you might see a red cross instead, meaning something needs fixing.

Step 6: Make a Change and Test It

CI/CD isn’t just about running your script once; it’s about automating tests every time your code changes.

  1. Edit your hello.py script—maybe change the message to Hello, GitHub Actions!.
  2. Commit the change.
  3. Your workflow will automatically run again. Easy, right?

Bonus Step: Add Some Tests

If you want to go one step further, add a test! Create a new file named test_hello.py and include the following code:

import pytest
from hello import my_function

def test_my_function():
    assert my_function() == "Hello, GitHub Actions!"

Update your .github/workflows/python-ci.yml :

  1. First, add pip install pytest under the ‘Install dependencies’ step, so that it looks like this:
    - name: Install dependencies
      run: |
        python -m pip install --upgrade pip
        pip install pytest
        if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
  1. Second, add the test after “Run Python script”:
    - name: Run Python script
      run: |
        python hello.py
        
    - name: Run tests
      run: |
        pytest

Conclusion

And there you have it! You just set up a basic CI/CD pipeline that runs your Python script every time you make a change. This example only covers the CI part, but we will explore the CD part in a future post. It might be simple now, but the skills you learn here will be the foundation of more complex automation in the future.

Published inData Engineering