Github Actions. CI/CD basics

From my experience, here are some best practices when working on git with a team:

Disable pushing directly to main branch;
All changes should come via Pull Request (PR);
A PR should have at least 1 approval (if more than 1 collaborator);
Disable merging a PR until checks pass;

Also, preferably, “update with rebase” when you can (not “update with merge commit”);

Usually to ensure code quality you would use run tests and linters locally.

Usually code storage solutions like Github/Gitlab allow you to run these tests in a virtual environment.

That way, you and your team can be sure that the tests are successful before merging a PR without having to re-run the tests on their machines.

The Github tool that allows you to run this sort of scripts in a virtual environment is called Github Actions.

To start using Github Actions on a repo, you would need to add a folder like .github/workflows in the root directory of your app.

Next, you could add yml scripts inside the folder. Here’s an example script:

The above script would run rubocop on your app whenever a pull request is created, or commits are pushed to it and provide a success/failure state:

Setting up the CI to run for linters is usally straightforward. You can find the code version of the above script in the article Install and use Rubocop.

The common “Checks” are:

rspec/minitest tests
rubocop linting
erb linting
javascript linting
deploying to a PR app

Setting up CI for tests #

This is usually harder, because it requires running the app.

Common “problems” are:

installing Redis
installing Postgresql
adding credentials

Now let’s

add a basic page to a Rails app
test the page locally
finally add a script to test the page with Github Actions

rails g controller static_pages landing_page

<!-- app/views/static_pages/landing_page.html.erb -->
<h1>hello world</h1>

# test/system/static_pages_test.rb
require 'application_system_test_case'
class StaticPagesTest < ApplicationSystemTestCase
  test 'visiting the homepage' do
    visit static_pages_landing_page_url
    assert_text 'hello world'
  end
end

To run system tests in CI, you will need to use headless chrome:

# test/application_system_test_case.rb
require 'test_helper'
class ApplicationSystemTestCase < ActionDispatch::SystemTestCase
  # driven_by :selenium, using: :chrome, screen_size: [1400, 1400]
  driven_by :selenium, using: :headless_chrome, screen_size: [1400, 1400]
end

Run tests:

# bin/rails test
# bin/rails test:all
bin/rails test --fail-fast

Run system tests:

bin/rails test:system

Troubleshoot Github Actions with rails credentials #

Running some tests would require having valid credentials.

Here’s how you can add master.key with a value 34tjk3ngiovv3j409jc34jt90v3q4jt4 to Github Actions using the Github GUI:

(Name should be RAILS_MASTER_KEY).

It can later be accessed in the CI yaml file as secrets.RAILS_MASTER_KEY ⤵️

Finally, the CI script #

This script works for me to install postgres, redis, run tests, re-run seeds.

# .github/workflows/.tests.yml
name: CI
on:
  pull_request:
    branches:
      - "*"
  push:
    branches:
      - main
jobs:
  install-cache:
    runs-on: ubuntu-latest
    timeout-minutes: 10
    steps:
      - name: Checkout Commit
        uses: actions/checkout@v3
      - name: Install Ruby
        uses: ruby/setup-ruby@v1
        with:
          bundler-cache: true
  test:
    runs-on: ubuntu-latest
    needs: install-cache
    timeout-minutes: 10
    services:
      postgres:
        image: postgres
        ports: ["5432:5432"]
        env:
          POSTGRES_USER: postgres
          POSTGRES_PASSWORD: password
        options: >-
          --health-cmd pg_isready
          --health-interval 10s
          --health-timeout 5s
          --health-retries 5
      redis:
        image: redis
        ports:
          - "6379:6379"
    steps:
      - name: Checkout Commit
        uses: actions/checkout@v3
      - name: Install Ruby
        uses: ruby/setup-ruby@v1
        with:
          bundler-cache: true
      - name: Install system dependencies
        run: |
          sudo apt-get -y update
      - name: Run tests
        env:
          RAILS_ENV: test
          DATABASE_URL: postgres://postgres:password@localhost:5432/myapp_test
          # RAILS_MASTER_KEY: ${{ secrets.RAILS_MASTER_KEY }}
        run: |
          bin/rails tailwindcss:build
          bin/rails db:create
          bin/rails db:schema:load
          bin/rails test --fail-fast
          bin/rails test:system
      - name: Smoke test database seeds
        env:
          RAILS_ENV: test
          DATABASE_URL: postgres://postgres:password@localhost:5432/myapp_test
          # RAILS_MASTER_KEY: ${{ secrets.RAILS_MASTER_KEY }}
        run: bundle exec rails db:reset

Finally, here are example CI scripts from open source RoR projects:

That’s it!

Setting up CI for tests #

Troubleshoot Github Actions with rails credentials #

Finally, the CI script #

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