github-actions-tutorial

Github Actions

GitHub Actions is a continuous integration and continuous delivery (CI/CD) platform that allows you to automate your build, test, and deployment pipeline.

Github provides Windows, linux and MacOs virtual machines to run workflow.

Worflow:

Configurable automated process. Defined by Yaml defined in .github/workflows (you can have multiple workflows)

Events:

Specific activity in the repository that triggers a workflow eg pull requests, issues, commits or on a schedule all events

Jobs

Set of steps in a workflow that execute on the same runner. Either a shell script or action Executed in order and dependent on one another. Data can be shared between actions Jobs can have dependencies on other Jobs

Actions

Custom application for github action that performs complex but repeated tasks You can write your own actions or find some in Github MarketPlace

Runners

Server that runs workflows. Each workflow runs on a newly configured VM

Event->Workflow->Jobs->Runner(Container)->Action

Example Workflow installs bats and tests the bats version

name: learn-github-actions
on: [push]
jobs:
  check-bats-version:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - uses: actions/setup-node@v3
        with:
          node-version: '14'
      - run: npm install -g bats
      - run: bats -v

Referencing action from market place in your action

Example

actions/setup-python

This action provides the following functionality for GitHub Actions users:

• Installing a version of Python or PyPy and (by default) adding it to the PATH
• Optionally caching dependencies for pip, pipenv and poetry
• Registering problem matchers for error output

The action.yml defines the parameters and optional parameters used by each action

Action.yml

name: Python package

on: [push]

jobs:
  build:

    runs-on: ubuntu-latest
    strategy:
      matrix:
        python-version: ["3.7", "3.8", "3.9", "3.10"]

    steps:
      - uses: actions/checkout@v3
      - name: Set up Python ${{ matrix.python-version }}
        uses: actions/setup-python@v4
        with:
          python-version: ${{ matrix.python-version }}
      - name: Install dependencies
        run: |
          python -m pip install --upgrade pip
          pip install flake8 pytest
          if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
      - name: Lint with flake8
        run: |
          # stop the build if there are Python syntax errors or undefined names
          flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
          # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
          flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
      - name: Test with pytest
        run: |
          pytest