Memento Github actions
Introduction to GitHub Actions¶
What is GitHub Actions? - GitHub Actions is a CI/CD and automation service provided by GitHub. - It allows you to automate workflows for tasks such as building, testing, deploying, and more. - Workflows are defined in YAML files and are triggered by specific GitHub events (e.g., push, pull request, issue creation).
Prerequisites¶
Before starting, you’ll need: - A GitHub account and access to a repository. - Basic knowledge of Git and GitHub. - Familiarity with YAML syntax.
Creating a GitHub Actions Workflow¶
What is a Workflow?
- A workflow is an automated process that runs in response to an event in your repository.
- It is defined in a .github/workflows/ directory within your repository.
Example of a Simple Workflow:
name: Simple CI
on: [push]
jobs:
build:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v2
- name: Set up Python
uses: actions/setup-python@v2
with:
python-version: '3.8'
- name: Install dependencies
run: |
python -m pip install --upgrade pip
pip install -r requirements.txt
- name: Run tests
run: |
pytest
push, pull_request).
- jobs: Contains the different jobs that will run as part of the workflow.
- steps: The individual actions to be executed in each job.
Workflow Triggers¶
Common Triggers:
- push: Triggered when changes are pushed to the repository.
- pull_request: Triggered when a pull request is opened or updated.
- workflow_dispatch: Manually triggered via the GitHub UI.
- schedule: Triggered on a scheduled basis (e.g., cron jobs).
on:
push:
branches:
- main
pull_request:
branches:
- main
workflow_dispatch:
Scheduled Triggers: - Example for running a job on a schedule:
on:
schedule:
- cron: '0 0 * * *'
Jobs and Runners¶
What is a Job?
- A job is a set of steps that execute on the same runner.
- Jobs are executed in parallel by default, but you can control the order with the needs: keyword.
Setting Up a Job:
jobs:
build:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v2
- name: Build Project
run: make build
Specifying Runners:
- You can specify the operating system for your runner (ubuntu-latest, windows-latest, macos-latest).
jobs:
build:
runs-on: ubuntu-latest
Job Dependencies (Using needs):
- You can define job dependencies so that one job waits for another to finish.
jobs:
build:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v2
- name: Build Project
run: make build
deploy:
runs-on: ubuntu-latest
needs: build
steps:
- uses: actions/checkout@v2
- name: Deploy Project
run: make deploy
Steps in a Job¶
Actions:
- Actions are reusable pieces of code in a step.
- GitHub provides a marketplace with a wide variety of actions (e.g., actions/checkout, actions/setup-python).
Example of an Action:
steps:
- uses: actions/checkout@v2
Running Shell Commands:
- You can run shell commands in steps using run:
steps:
- name: Run tests
run: |
pip install -r requirements.txt
pytest
Caching Dependencies¶
Using Cache in Workflows: - GitHub Actions supports caching dependencies between workflow runs to speed up builds.
jobs:
build:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v2
- name: Cache Python dependencies
uses: actions/cache@v2
with:
path: ~/.cache/pip
key: ${{ runner.os }}-python-${{ hashFiles('**/requirements.txt') }}
restore-keys: |
${{ runner.os }}-python-
- name: Install dependencies
run: pip install -r requirements.txt
Cache Key Explanation:
- The key is based on the hash of requirements.txt, which ensures cache is refreshed when dependencies change.
Environment Variables and Secrets¶
Environment Variables: - You can set environment variables at the job or step level.
jobs:
build:
runs-on: ubuntu-latest
steps:
- name: Set environment variable
run: echo "MY_VAR=some_value" >> $GITHUB_ENV
Using Secrets:
- Secrets are stored securely in GitHub and can be accessed during workflows.
- Store secrets in the GitHub repository settings under Settings > Secrets.
jobs:
deploy:
runs-on: ubuntu-latest
steps:
- name: Deploy to Server
run: ./deploy.sh
env:
API_KEY: ${{ secrets.API_KEY }}
Matrix Builds¶
Running Tests Across Multiple Configurations: - Use a matrix strategy to run jobs across multiple configurations (e.g., different versions of Python, Node.js, etc.).
jobs:
build:
runs-on: ubuntu-latest
strategy:
matrix:
python-version: [3.7, 3.8, 3.9]
steps:
- uses: actions/checkout@v2
- name: Set up Python
uses: actions/setup-python@v2
with:
python-version: ${{ matrix.python-version }}
- name: Install dependencies
run: pip install -r requirements.txt
- name: Run tests
run: pytest
Matrix Example Explanation:
- This matrix will run the build job for Python versions 3.7, 3.8, and 3.9.
Notifications and Alerts¶
Sending Notifications: - GitHub Actions allows you to send notifications to Slack, email, etc., using third-party actions or webhooks.
Example: Sending Slack Notification on Success:
jobs:
notify:
runs-on: ubuntu-latest
steps:
- uses: rtCamp/action-slack-notify@v2
with:
status: ${{ job.status }}
webhook-url: ${{ secrets.SLACK_WEBHOOK_URL }}
Manual Triggers (workflow_dispatch)¶
Triggering Workflows Manually: - You can define workflows that are manually triggered via the GitHub UI or API.
on:
workflow_dispatch:
Conclusion¶
Key Takeaways:
- GitHub Actions enables powerful automation workflows directly within your GitHub repository.
- Workflows are defined in .github/workflows/ and consist of jobs, steps, and triggers.
- You can run jobs on multiple environments, cache dependencies, and manage secrets securely.
- Use matrix builds to test across multiple configurations and manual triggers for on-demand workflows.
Next Steps:
- Create a .github/workflows/ directory and start defining simple workflows.
- Explore GitHub Actions Marketplace to add pre-built actions to your workflows.
- Use caching, matrix builds, and environment variables to optimize and customize your workflows.
Last update : 2025-05-04T19:41:43Z