GitHub Actions Tutorial — Checkout & Setup

Checkout & Setup Actions

Two actions appear in virtually every workflow: actions/checkout (to get your code) and actions/setup-* (to install a language runtime). Understanding their options is essential.

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actions/checkout

By default, actions/checkout@v4 clones your repository at the commit that triggered the workflow.

Basic Usage

steps:
  - uses: actions/checkout@v4
  - run: ls -la     # your repo files are here

Common Options

steps:
  - uses: actions/checkout@v4
    with:
      # Check out a specific branch or tag
      ref: 'develop'

      # Check out full history (for changelogs, git blame)
      fetch-depth: 0          # 0 = full history, default is 1 (shallow)

      # Check out submodules
      submodules: true         # or 'recursive'

      # Check out a different repository
      repository: 'owner/other-repo'
      token: ${{ secrets.PAT }}

      # Check out to a specific path
      path: 'my-repo'

Key Options Reference

Option	Default	Purpose
ref	Trigger ref	Branch, tag, or SHA to checkout
fetch-depth	1	Git history depth (0 = full)
submodules	false	Initialize submodules
token	github.token	Auth token (needed for private repos)
path	.	Directory to clone into
clean	true	Clean before checkout

When to Use fetch-depth: 0

Use Case	fetch-depth
Standard CI (build/test)	1 (default, fastest)
Generate changelog	0 (needs full history)
Git blame / git log	0
Semantic versioning from tags	0
Count commits since last tag	0

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actions/setup-node

Install a specific Node.js version:

steps:
  - uses: actions/checkout@v4
  - uses: actions/setup-node@v4
    with:
      node-version: 20
  - run: node --version     # v20.x.x

Options

steps:
  - uses: actions/setup-node@v4
    with:
      node-version: '20.x'              # major version
      node-version-file: '.nvmrc'       # read from file
      cache: 'npm'                       # cache npm dependencies
      registry-url: 'https://npm.pkg.github.com'   # for publishing

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actions/setup-python

steps:
  - uses: actions/checkout@v4
  - uses: actions/setup-python@v5
    with:
      python-version: '3.12'
  - run: python --version    # Python 3.12.x

Options

steps:
  - uses: actions/setup-python@v5
    with:
      python-version: '3.12'
      cache: 'pip'                    # cache pip dependencies
      cache-dependency-path: 'requirements.txt'

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actions/setup-java

steps:
  - uses: actions/checkout@v4
  - uses: actions/setup-java@v4
    with:
      distribution: 'temurin'     # Eclipse Temurin (recommended)
      java-version: '21'
      cache: 'maven'
  - run: java --version

Java Distributions

Distribution	Value
Eclipse Temurin	temurin
Azul Zulu	zulu
Amazon Corretto	corretto
Microsoft Build	microsoft
Oracle JDK	oracle

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actions/setup-go

steps:
  - uses: actions/checkout@v4
  - uses: actions/setup-go@v5
    with:
      go-version: '1.22'
      cache: true
  - run: go version

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actions/setup-dotnet

steps:
  - uses: actions/checkout@v4
  - uses: actions/setup-dotnet@v4
    with:
      dotnet-version: '8.0.x'
  - run: dotnet --version

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Pattern — Setup with Caching

Every setup-* action supports built-in dependency caching:

steps:
  - uses: actions/checkout@v4

  - uses: actions/setup-node@v4
    with:
      node-version: 20
      cache: 'npm'           # automatically caches ~/.npm

  - run: npm ci              # fast — uses cached dependencies
  - run: npm test

Caching dramatically speeds up workflows by skipping redundant dependency downloads. We cover this in depth in Artifacts & Caching.

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Common Mistakes

Mistake	Fix
Forgot actions/checkout	Without it, your repo files aren’t on the runner
Shallow clone breaks git log	Use fetch-depth: 0 for full history
Wrong Node.js version	Check .nvmrc or package.json engines field
Cache not working	Ensure the cache: input matches your package manager

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Quick Reference

Action	Purpose	Key Input
actions/checkout@v4	Clone repository	ref, fetch-depth
actions/setup-node@v4	Install Node.js	node-version, cache: npm
actions/setup-python@v5	Install Python	python-version, cache: pip
actions/setup-java@v4	Install Java	distribution, java-version
actions/setup-go@v5	Install Go	go-version, cache: true
actions/setup-dotnet@v4	Install .NET	dotnet-version

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