Github Actions Reusable

GitHub Actions Reusable Workflows

Trigger: Use when you have identical CI/CD steps across multiple repos or want to share action logic.

Reusable Workflows (called from other workflows)

Step 1: Create the Called Workflow

.github/workflows/deploy.yml:

name: Deploy
on:
  workflow_call:
    inputs:
      environment:
        required: true
        type: string
      version:
        required: false
        type: string
        default: latest
    secrets:
      CLOUD_TOKEN:
        required: true
    outputs:
      url:
        value: ${{ jobs.deploy.outputs.url }}
jobs:
  deploy:
    runs-on: ubuntu-latest
    outputs:
      url: ${{ steps.set-url.outputs.url }}
    steps:
      - id: set-url
        run: echo "url=https://${{ inputs.environment }}.example.com" >> $GITHUB_OUTPUT

Step 2: Call It

jobs:
  deploy:
    uses: org/repo/.github/workflows/deploy.yml@v1
    with:
      environment: staging
      version: v1.2.0
    secrets:
      CLOUD_TOKEN: ${{ secrets.CLOUD_TOKEN }}

Composite Actions

.github/actions/setup-rust/action.yml:

name: "Setup Rust"
description: "Install Rust toolchain with caching"
inputs:
  toolchain:
    required: false
    default: stable
runs:
  using: "composite"
  steps:
    - run: rustup toolchain install ${{ inputs.toolchain }}
      shell: bash
    - uses: actions/cache@v4
      with:
        path: ~/.cargo/registry
        key: cargo-${{ hashFiles('**/Cargo.lock') }}

Use the Composite

steps:
  - uses: actions/checkout@v4
  - uses: ./.github/actions/setup-rust
    with:
      toolchain: nightly
  - run: cargo build

Best Practices

• Version with tags: uses: org/repo/.github/workflows/ci.yml@v1 not @main
• Validate inputs: Use type: boolean for type safety
• Map secrets explicitly: They don't auto-flow to called workflows

Pitfalls

• No env context in reusable workflows: Pass values as inputs instead
• Composite actions: Don't run in caller's workspace — use ${{ github.workspace }}
• Max depth: 4 levels of nested reusable workflows

Verification

grep -r "uses:.*/" .github/workflows/ | grep -v "actions/"