ci: skip tests/clippy/udeps for docs-only changes

Implemented a DRY approach using a composite action that detects when
only documentation files have changed. This speeds up CI for docs-only
PRs while keeping all checks green.

- Created reusable composite action '.github/actions/check-docs-only'
- Refactored workflow to use the composite action across all jobs
- Tests, clippy, and udeps checks now pass immediately for docs-only changes

Author: ammario

.github/actions/check-docs-only/action.yml

@@ -0,0 +1,34 @@
+name: 'Check Docs Only Changes'
+description: 'Check if only documentation files were changed'
+outputs:
+  docs-only:
+    description: "True if only documentation files were changed"
+    value: ${{ steps.check.outputs.docs_only }}
+runs:
+  using: "composite"
+  steps:
+    - name: Check if only docs changed
+      id: check
+      shell: bash
+      run: |
+        # Determine the base SHA for comparison
+        if [ "${{ github.event_name }}" = "pull_request" ]; then
+          # For PRs, compare against the base branch
+          BASE_SHA="${{ github.event.pull_request.base.sha }}"
+          FILES_CHANGED=$(git diff --name-only "${BASE_SHA}"...HEAD)
+        else
+          # For pushes, compare with previous commit
+          FILES_CHANGED=$(git diff --name-only HEAD~1...HEAD 2>/dev/null || echo "")
+        fi
+        
+        # Check if all changed files are in docs/ directory
+        if [ -z "$FILES_CHANGED" ]; then
+          echo "docs_only=false" >> $GITHUB_OUTPUT
+          echo "No files changed"
+        elif echo "$FILES_CHANGED" | grep -vE '^docs/' > /dev/null; then
+          echo "docs_only=false" >> $GITHUB_OUTPUT
+          echo "Non-documentation files changed"
+        else
+          echo "docs_only=true" >> $GITHUB_OUTPUT
+          echo "All changes are in docs/ folder, checks will pass automatically"
+        fi

.github/workflows/tests.yml

@@ -19,31 +19,54 @@ jobs:
 
     steps:
       - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Check for docs-only changes
+        id: docs-check
+        uses: ./.github/actions/check-docs-only
 
       - name: Install Rust
+        if: steps.docs-check.outputs.docs-only != 'true'
         uses: dtolnay/rust-toolchain@stable
         with:
           toolchain: stable
 
       - name: Setup Rust cache
+        if: steps.docs-check.outputs.docs-only != 'true'
         uses: Swatinem/rust-cache@v2
         with:
           shared-key: ${{ runner.os }}
 
       - name: Install nextest
+        if: steps.docs-check.outputs.docs-only != 'true'
         uses: taiki-e/install-action@nextest
         with:
           tool: nextest
 
       - name: Run all tests
+        if: steps.docs-check.outputs.docs-only != 'true'
         run: cargo nextest run --profile ci
 
+      - name: Skip tests for docs-only changes
+        if: steps.docs-check.outputs.docs-only == 'true'
+        run: echo "✅ Skipping tests - only documentation changed"
+
   test-linux:
     name: Linux Tests
     runs-on: [self-hosted, linux]
 
     steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Check for docs-only changes
+        id: docs-check
+        uses: ./.github/actions/check-docs-only
+
       - name: Fix permissions from previous runs
+        if: steps.docs-check.outputs.docs-only != 'true'
         run: |
           # Clean up any files left from previous sudo runs before checkout
           # Use GITHUB_WORKSPACE parent directory or current working directory
@@ -55,14 +78,15 @@ jobs:
           if [ -d /home/ci/.cargo ]; then
             sudo chown -R ci:ci /home/ci/.cargo || true
           fi
-      - uses: actions/checkout@v4
 
       - name: Install Rust
+        if: steps.docs-check.outputs.docs-only != 'true'
         uses: dtolnay/rust-toolchain@stable
         with:
           toolchain: stable
 
       - name: Fix permissions on current directory
+        if: steps.docs-check.outputs.docs-only != 'true'
         run: |
           # Clean up any files left from previous sudo runs
           if [ -d target ]; then
@@ -78,45 +102,57 @@ jobs:
           fi
 
       - name: Setup Rust cache
+        if: steps.docs-check.outputs.docs-only != 'true'
         uses: Swatinem/rust-cache@v2
         with:
           shared-key: ${{ runner.os }}
 
       - name: Setup Rust environment
+        if: steps.docs-check.outputs.docs-only != 'true'
         run: |
           source ~/.cargo/env
           rustup default stable
 
       - name: Install nextest
+        if: steps.docs-check.outputs.docs-only != 'true'
         uses: taiki-e/install-action@nextest
         with:
           tool: nextest
 
       - name: Fix target directory permissions from previous runs
+        if: steps.docs-check.outputs.docs-only != 'true'
         run: |
           if [ -d target ]; then
             sudo chown -R ci:ci target || true
           fi
 
       - name: Run all tests (non-root)
+        if: steps.docs-check.outputs.docs-only != 'true'
         run: |
           source ~/.cargo/env
           cargo nextest run --profile ci --verbose -E 'not (binary(linux_integration) or binary(weak_integration))'
 
       - name: Install dependencies for weak mode (curl)
+        if: steps.docs-check.outputs.docs-only != 'true'
         run: sudo apt-get update && sudo apt-get install -y curl
 
       - name: Run weak mode integration tests (Linux)
+        if: steps.docs-check.outputs.docs-only != 'true'
         run: |
           source ~/.cargo/env
           cargo nextest run --profile ci --test weak_integration
 
       - name: Run Linux jail integration tests (sudo)
+        if: steps.docs-check.outputs.docs-only != 'true'
         run: |
           source ~/.cargo/env
           # Run Linux-specific jail tests with sudo to satisfy root requirements
           sudo -E $(which cargo) nextest run --profile ci --test linux_integration --verbose
 
+      - name: Skip tests for docs-only changes
+        if: steps.docs-check.outputs.docs-only == 'true'
+        run: echo "✅ Skipping tests - only documentation changed"
+
   clippy:
     name: Clippy (${{ matrix.os }})
     runs-on: ${{ matrix.os }}
@@ -126,21 +162,34 @@ jobs:
 
     steps:
       - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Check for docs-only changes
+        id: docs-check
+        uses: ./.github/actions/check-docs-only
 
       - name: Install Rust
+        if: steps.docs-check.outputs.docs-only != 'true'
         uses: dtolnay/rust-toolchain@stable
         with:
           toolchain: stable
           components: clippy
 
       - name: Setup Rust cache
+        if: steps.docs-check.outputs.docs-only != 'true'
         uses: Swatinem/rust-cache@v2
         with:
           shared-key: ${{ runner.os }}
 
       - name: Run clippy
+        if: steps.docs-check.outputs.docs-only != 'true'
         run: cargo clippy --all-targets -- -D warnings
 
+      - name: Skip clippy for docs-only changes
+        if: steps.docs-check.outputs.docs-only == 'true'
+        run: echo "✅ Skipping clippy - only documentation changed"
+
   fmt:
     name: Format
     runs-on: ubuntu-latest-8-cores
@@ -168,21 +217,31 @@ jobs:
 
     steps:
       - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Check for docs-only changes
+        id: docs-check
+        uses: ./.github/actions/check-docs-only
 
       - name: Install Rust (nightly for cargo-udeps)
+        if: steps.docs-check.outputs.docs-only != 'true'
         uses: dtolnay/rust-toolchain@stable
         with:
           toolchain: nightly
 
       - name: Setup Rust cache
+        if: steps.docs-check.outputs.docs-only != 'true'
         uses: Swatinem/rust-cache@v2
         with:
           shared-key: ${{ runner.os }}
 
       - name: Install cargo-udeps
+        if: steps.docs-check.outputs.docs-only != 'true'
         uses: taiki-e/install-action@cargo-udeps
 
       - name: Check for unused dependencies
+        if: steps.docs-check.outputs.docs-only != 'true'
         run: |
           set -euo pipefail
           # Run with nightly; capture output without failing the step
@@ -206,3 +265,7 @@ jobs:
             echo "Unused dependencies detected"
             exit 1
           fi
+
+      - name: Skip udeps for docs-only changes
+        if: steps.docs-check.outputs.docs-only == 'true'
+        run: echo "✅ Skipping unused dependency check - only documentation changed"