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✅ Example 1: Simple Node.js CI

Key Concepts Learned

1. Workflow Triggers (on:)

on:
  push:
    branches: [ master, feature/github-actions-practice ]
  pull_request:
    branches: [ master ]
  workflow_dispatch:
  • push: Runs when code is pushed to specified branches
  • pull_request: Runs when PR is created/updated
  • workflow_dispatch: Allows manual triggering from GitHub UI

2. Jobs

jobs:
  build:
    runs-on: ubuntu-latest
  • Each workflow can have multiple jobs
  • Jobs run in parallel by default
  • runs-on specifies the runner (Ubuntu, Windows, macOS)

3. Steps

Two types of steps:

Action Steps (uses):

- name: Checkout code
  uses: actions/checkout@v4

Command Steps (run):

- name: Install dependencies
  run: npm ci

4. Why npm ci instead of npm install?

npm install npm ci
Updates package-lock.json Requires package-lock.json
Installs latest compatible versions Installs exact versions
Slower Faster
Good for development

Perfect for CI/CD

Example 1 Questions

Q1: What is the difference between npm install and npm ci? Answer:

  • npm ci (clean install) is designed for CI/CD environments
  • It's faster because it skips certain user-facing features
  • It requires package-lock.json and installs exact versions
  • It removes node_modules before installing (clean slate)
  • npm install can modify package-lock.json, while npm ci never does

Q2: Why do we need actions/checkout@v4? Answer:

  • GitHub Actions runners start with an empty workspace
  • actions/checkout@v4 clones your repository code into the runner
  • Without it, your code wouldn't be available for testing/building
  • The @v4 specifies the version of the action to use

Q3: What does runs-on: ubuntu-latest mean? Answer:

  • Specifies which operating system to run the job on
  • ubuntu-latest uses the latest Ubuntu Linux version (currently 22.04)
  • Other options: windows-latest, macos-latest
  • GitHub provides free runners for public repositories

Q4: What is workflow_dispatch and when would you use it? Answer:

  • Allows manual triggering of workflows from GitHub UI
  • Useful for:
    • On-demand deployments
    • Manual testing
    • Workflows that shouldn't run automatically
    • Workflows with user inputs
  • Can accept input parameters for customization

Q5: Explain the workflow execution order

Answer: Steps execute sequentially within a job:

  1. Checkout code from repository
  2. Setup Node.js environment (version 22)
  3. Install dependencies using npm ci
  4. Run tests (fails if tests fail)
  5. Build project (only runs if tests pass)

If any step fails, subsequent steps are skipped and the workflow fails.