Git Diff Analyzer for CI/CD

A Node.js tool to analyze git diffs and commit details for CI/CD workflows. Specifically designed to work in GitHub Actions and other CI/CD environments.

Installation

As a local package

npm install

As a global package

npm install -g .

As a dependency in another project

npm install --save ci-cd-git-diff-analyzer
# OR
npm install --save git+https://github.com/AsijitM/ci-cd-git-diff-analyzer.git

Usage

Environment Variables

Create a .env file in your project root (see .env.example):

GITHUB_TOKEN=your_github_token_here
REPO_OWNER=YourGithubUsername
REPO_NAME=YourRepoName
BRANCH=main

Command Line Interface

# Show git diff between last two commits
node index.js --diff
# OR if installed globally
git-diff-analyzer --diff
# OR using the shorter alias
gda --diff

# Using npx (without installing globally)
npx git-diff-analyzer --diff
# OR using the shorter alias with npx
npx gda --diff

# Fetch commit details from GitHub
node index.js --commit
# OR if installed globally
git-diff-analyzer --commit
# OR using npx
npx git-diff-analyzer --commit

# Show the full diff output in the console
node index.js --diff --verbose
# OR if installed globally
git-diff-analyzer --diff --verbose

Ignoring Files

The tool automatically ignores certain files that are commonly not relevant for CI/CD decisions:

// Files ignored by default
const IGNORED_FILES = [
  '.github/workflows/CD',
  '.gitignore',
  'extract_tags.js',
  'package-lock.json',
  'package.json',
  'sample_test.js'
];

You can customize this list by modifying the IGNORED_FILES array in the index.js file.

Usage in CI/CD (GitHub Actions)

Add the following to your workflow YAML file:

jobs:
  analyze_changes:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v3
        with:
          fetch-depth: 0  # Important: fetch all history for accurate diffs

      - name: Setup Node.js
        uses: actions/setup-node@v3
        with:
          node-version: '16'

      - name: Install dependencies
        run: npm install ci-cd-git-diff-analyzer

      # Option 1: Using npx (recommended)
      - name: Analyze Git Diff
        id: git-diff
        run: npx git-diff-analyzer --diff
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

      # Option 2: Using full path (alternative)
      # - name: Analyze Git Diff
      #   id: git-diff
      #   run: node node_modules/ci-cd-git-diff-analyzer/index.js --diff
      #   env:
      #     GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

      # Option 3: Using shorter alias (alternative)
      # - name: Analyze Git Diff
      #   id: git-diff
      #   run: npx gda --diff
      #   env:
      #     GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

      # Example of using the diff output in subsequent steps
      - name: Check Diff Results
        if: success()
        run: |
          echo "Diff found: ${{ steps.git-diff.outputs.diff_found }}"
          echo "Diff output saved to: ${{ steps.git-diff.outputs.diff_output_path }}"

          # Example: only run certain steps if changes to specific files
          if grep -q "src/api" git-diff-output.txt; then
            echo "API changes detected"
            # Run API-specific CI steps
          fi

The tool automatically:

1. Detects it's running in CI environment
2. Handles GitHub's shallow clone correctly
3. Works with both PR and Push events
4. Exports outputs that can be used in subsequent workflow steps
5. Creates output files with detailed diff information

Advanced CI/CD Usage Examples

Conditional Building and Testing

This example shows how to use the analyzer to run specific build and test steps only when relevant files have changed:

name: CI/CD with Selective Testing

on:
  push:
    branches: [ main ]
  pull_request:
    branches: [ main ]

jobs:
  analyze_and_test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
        with:
          fetch-depth: 0

      - name: Setup Node.js
        uses: actions/setup-node@v3
        with:
          node-version: '16'

      - name: Install dependencies
        run: |
          npm ci
          npm install ci-cd-git-diff-analyzer

      - name: Run Git Diff Analyzer
        id: git-diff
        run: node node_modules/ci-cd-git-diff-analyzer/index.js --diff
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

      # Conditional frontend testing
      - name: Frontend Tests
        if: success()
        run: |
          if grep -q "src/frontend\|src/components\|src/pages" git-diff-output.txt; then
            echo "Frontend changes detected, running frontend tests"
            npm run test:frontend
          else
            echo "No frontend changes detected, skipping frontend tests"
          fi

      # Conditional backend testing
      - name: Backend Tests
        if: success()
        run: |
          if grep -q "src/backend\|src/api\|src/models" git-diff-output.txt; then
            echo "Backend changes detected, running backend tests"
            npm run test:backend
          else
            echo "No backend changes detected, skipping backend tests"
          fi

Commit Analysis and Deployment

This example shows how to use commit details to make deployment decisions:

name: CI/CD with Commit Analysis

on:
  push:
    branches: [ main ]

jobs:
  analyze_and_deploy:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
        with:
          fetch-depth: 0

      - name: Setup Node.js
        uses: actions/setup-node@v3
        with:
          node-version: '16'

      - name: Install dependencies
        run: npm install ci-cd-git-diff-analyzer

      - name: Analyze Commit Details
        id: commit-details
        run: node node_modules/ci-cd-git-diff-analyzer/index.js --commit
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

      # Deploy based on commit message
      - name: Conditional Deployment
        if: success()
        run: |
          COMMIT_MSG=$(cat commit-details.json | jq -r '.commit.message')

          if [[ "$COMMIT_MSG" == *"[deploy]"* ]]; then
            echo "Deployment trigger found in commit message!"
            # Deployment commands here
          elif [[ "$COMMIT_MSG" == *"[minor]"* ]]; then
            echo "Minor change detected, skipping deployment"
          else
            echo "Standard commit, running normal CI process"
          fi

For more examples, see the complete-ci-workflow-example.yml file in this repository.

Usage in Another Project

const { getGitDiff, fetchCommitDetails } = require('ci-cd-git-diff-analyzer');

async function run() {
  // Get git diff between last two commits
  const diff = await getGitDiff();

  if (diff && diff.includes('package.json')) {
    console.log('Dependencies may have changed!');
    // Run npm install
  }

  // Fetch commit details from GitHub
  const commitDetails = await fetchCommitDetails();

  if (commitDetails && commitDetails.commit.message.includes('[important]')) {
    console.log('Important commit detected!');
    // Take special actions
  }
}

run();

Features

• Fetches git diff between the last two commits
• Handles edge cases like repositories with only one commit
• Automatically finds the git repository in the project
• Fetches commit details from GitHub API
• Configurable via environment variables
• Special handling for CI environments (GitHub Actions, GitLab CI, etc.)
• Output files for easy consumption by other CI/CD steps
• GitHub Actions output variables for workflow integration

Troubleshooting

Error: "fatal: ambiguous argument 'HEAD~1'"

This error occurs when:

• The repository has no commits
• The script is not running in a git repository
• You're using it as a package in another project

The script will now attempt to find the git repository automatically and handle these cases gracefully.

Error: "Request failed with status code 401" when fetching commit details

This error occurs when the GitHub token is invalid or missing. Make sure to set the GITHUB_TOKEN environment variable in your .env file or in your CI/CD environment.

GitHub Actions: "The set-output command is deprecated"

If you see this warning in GitHub Actions, it's because GitHub has updated how outputs are set. The tool has been updated to use the new method via GITHUB_OUTPUT environment file.