Deployment with Git - Complete Guide

# Git Hooks Deployment

# 1. Create post-receive hook
# On server: /var/repo/myapp.git/hooks/post-receive
#!/bin/bash
WORK_TREE=/var/www/myapp
GIT_DIR=/var/repo/myapp.git

# Deploy to production
git --work-tree=$WORK_TREE --git-dir=$GIT_DIR checkout -f

# Run build commands
cd $WORK_TREE
npm install --production
npm run build

# Restart services
sudo systemctl restart nginx
sudo systemctl restart myapp

# 2. Pre-receive hook validation
#!/bin/bash
# Validate deployment
while read oldrev newrev refname; do
    if [[ $refname = "refs/heads/main" ]]; then
        # Run tests
        git --work-tree=/tmp/test --git-dir=/var/repo/myapp.git checkout -f $newrev
        cd /tmp/test
        npm test
        if [ $? -ne 0 ]; then
            echo "Tests failed, deployment rejected"
            exit 1
        fi
    fi
done

# 3. Update hook for staging
#!/bin/bash
# Deploy to staging
WORK_TREE=/var/www/staging
GIT_DIR=/var/repo/myapp.git

git --work-tree=$WORK_TREE --git-dir=$GIT_DIR checkout -f staging

cd $WORK_TREE
npm install
npm run build:staging

# 4. Branch-based deployment
#!/bin/bash
while read oldrev newrev refname; do
    branch=$(git rev-parse --symbolic --abbrev-ref $refname)
    
    case $branch in
        main)
            deploy_production
            ;;
        staging)
            deploy_staging
            ;;
        develop)
            deploy_development
            ;;
    esac
done

# 5. Environment-specific deployment
deploy_production() {
    WORK_TREE=/var/www/production
    GIT_DIR=/var/repo/myapp.git
    
    git --work-tree=$WORK_TREE --git-dir=$GIT_DIR checkout -f main
    
    cd $WORK_TREE
    npm install --production
    npm run build:production
    
    # Health check
    curl -f http://localhost:3000/health || exit 1
    
    # Restart services
    sudo systemctl restart myapp
}

deploy_staging() {
    WORK_TREE=/var/www/staging
    GIT_DIR=/var/repo/myapp.git
    
    git --work-tree=$WORK_TREE --git-dir=$GIT_DIR checkout -f staging
    
    cd $WORK_TREE
    npm install
    npm run build:staging
}

# GitHub Actions Deployment

# .github/workflows/deploy.yml
name: Deploy to Production

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

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v3
    
    - name: Setup Node.js
      uses: actions/setup-node@v3
      with:
        node-version: '18'
        cache: 'npm'
    
    - name: Install dependencies
      run: npm ci
    
    - name: Run tests
      run: npm test
    
    - name: Build application
      run: npm run build

  deploy:
    needs: test
    runs-on: ubuntu-latest
    if: github.ref == 'refs/heads/main'
    
    steps:
    - uses: actions/checkout@v3
    
    - name: Setup Node.js
      uses: actions/setup-node@v3
      with:
        node-version: '18'
    
    - name: Install dependencies
      run: npm ci
    
    - name: Build application
      run: npm run build
    
    - name: Deploy to server
      uses: appleboy/ssh-action@v0.1.5
      with:
        host: ${{ secrets.HOST }}
        username: ${{ secrets.USERNAME }}
        key: ${{ secrets.SSH_KEY }}
        script: |
          cd /var/www/myapp
          git pull origin main
          npm install --production
          npm run build
          sudo systemctl restart myapp

# 2. Multi-environment deployment
name: Multi-Environment Deployment

on:
  push:
    branches: [ main, staging, develop ]

jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v3
    
    - name: Determine environment
      id: env
      run: |
        if [[ $GITHUB_REF == 'refs/heads/main' ]]; then
          echo "environment=production" >> $GITHUB_OUTPUT
        elif [[ $GITHUB_REF == 'refs/heads/staging' ]]; then
          echo "environment=staging" >> $GITHUB_OUTPUT
        else
          echo "environment=development" >> $GITHUB_OUTPUT
        fi
    
    - name: Deploy to ${{ steps.env.outputs.environment }}
      uses: appleboy/ssh-action@v0.1.5
      with:
        host: ${{ secrets.HOST }}
        username: ${{ secrets.USERNAME }}
        key: ${{ secrets.SSH_KEY }}
        script: |
          cd /var/www/${{ steps.env.outputs.environment }}
          git pull origin ${{ github.ref_name }}
          npm install
          npm run build:${{ steps.env.outputs.environment }}
          sudo systemctl restart myapp-${{ steps.env.outputs.environment }}

# Deployment Strategies

# 1. Blue-Green Deployment
#!/bin/bash
# Blue-Green deployment script

CURRENT_COLOR=$(cat /var/www/current_color)
if [ "$CURRENT_COLOR" = "blue" ]; then
    NEW_COLOR="green"
    OLD_COLOR="blue"
else
    NEW_COLOR="blue"
    OLD_COLOR="green"
fi

# Deploy to new environment
git --work-tree=/var/www/$NEW_COLOR --git-dir=/var/repo/myapp.git checkout -f main
cd /var/www/$NEW_COLOR
npm install --production
npm run build

# Health check
curl -f http://localhost:3001/health || exit 1

# Switch traffic
sudo ln -sf /var/www/$NEW_COLOR /var/www/current
echo $NEW_COLOR > /var/www/current_color

# Restart services
sudo systemctl restart nginx
sudo systemctl restart myapp

# 2. Rolling Deployment
#!/bin/bash
# Rolling deployment script

SERVERS=("server1" "server2" "server3")

for server in "${SERVERS[@]}"; do
    echo "Deploying to $server..."
    
    ssh $server "cd /var/www/myapp && git pull origin main"
    ssh $server "cd /var/www/myapp && npm install --production"
    ssh $server "cd /var/www/myapp && npm run build"
    ssh $server "sudo systemctl restart myapp"
    
    # Health check
    ssh $server "curl -f http://localhost:3000/health" || exit 1
    
    echo "Deployment to $server completed"
done

# 3. Canary Deployment
#!/bin/bash
# Canary deployment script

# Deploy to canary server
git --work-tree=/var/www/canary --git-dir=/var/repo/myapp.git checkout -f main
cd /var/www/canary
npm install --production
npm run build

# Route 10% traffic to canary
sudo nginx -s reload

# Monitor canary for 10 minutes
sleep 600

# Check metrics
CANARY_ERROR_RATE=$(curl -s http://localhost:3001/metrics | grep error_rate)
if [ "$CANARY_ERROR_RATE" -lt "0.01" ]; then
    # Deploy to production
    deploy_production
else
    # Rollback canary
    sudo nginx -s reload
    exit 1
fi

# 4. Feature Flag Deployment
#!/bin/bash
# Feature flag deployment

# Deploy with feature flags
git --work-tree=/var/www/myapp --git-dir=/var/repo/myapp.git checkout -f main
cd /var/www/myapp
npm install --production

# Set feature flags
export FEATURE_NEW_UI=true
export FEATURE_BETA_API=false

npm run build
sudo systemctl restart myapp

# 5. Database Migration Deployment
#!/bin/bash
# Database migration deployment

# Backup database
mysqldump -u root -p myapp > /backup/myapp_$(date +%Y%m%d_%H%M%S).sql

# Run migrations
cd /var/www/myapp
npm run migrate:up

# Deploy application
git --work-tree=/var/www/myapp --git-dir=/var/repo/myapp.git checkout -f main
npm install --production
npm run build

# Health check
curl -f http://localhost:3000/health || {
    # Rollback migration
    npm run migrate:down
    exit 1
}

sudo systemctl restart myapp