README

Deploy your applications with zero downtime.
Simple, secure, and reliable deployments using atomic symlink switching.

What is ZDT?

ZDT (Zero Downtime Tool) is a deployment tool that ensures your application stays online during deployments. It deploys to a new directory, runs all setup tasks, then switches traffic atomically. If anything fails, it automatically rolls back.

Perfect for: PHP/Laravel applications, Node.js apps, static sites, or any web application.

How It Works

1. Connect to server via SSH
2. Clone code to new release directory (releases/20231202143000/)
3. Install dependencies & run hooks
4. Run database migrations
5. Switch symlink atomically (current → new release)
6. Health check & cleanup old releases
7. Auto-rollback if anything fails

Key Features:

• ✅ Zero downtime - atomic symlink switching
• ✅ Automatic rollbacks on failure
• ✅ Health checks - validate deployments succeed
• ✅ Deployment locks - prevent concurrent deployments
• ✅ Database backups - automated pre-migration backups
• ✅ Notifications - Slack, Discord webhooks
• ✅ Release history & instant rollback
• ✅ Deployment hooks for custom tasks
• ✅ Works with GitHub Actions, GitLab CI, or locally

Installation

composer global require veltix/zdt

Or install in your CI/CD workflow (no global install needed).

Quick Start

1. Setup GitHub Secrets

Go to your repository Settings → Secrets → Actions and add:

2. Create Workflow

Create .github/workflows/deploy.yml:

name: Deploy

on:
  push:
    branches: [main]

jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - uses: shivammathur/setup-php@v2
        with:
          php-version: '8.2'

      - name: Deploy
        env:
          DEPLOY_HOST: ${{ secrets.DEPLOY_HOST }}
          DEPLOY_USERNAME: ${{ secrets.DEPLOY_USERNAME }}
          DEPLOY_KEY_PATH: ${{ secrets.DEPLOY_SSH_KEY }}
          DEPLOY_REPO_URL: https://github.com/${{ github.repository }}.git
          DEPLOY_PATH: ${{ secrets.DEPLOY_PATH }}
          DEPLOY_BRANCH: ${{ github.ref_name }}
        run: |
          composer global require veltix/zdt
          echo "$DEPLOY_KEY_PATH" > ~/.ssh/deploy_key
          chmod 600 ~/.ssh/deploy_key
          export DEPLOY_KEY_PATH=~/.ssh/deploy_key
          zdt deploy

3. Push & Deploy

git push origin main

Your app deploys automatically with zero downtime! 🚀

Configuration Methods

ZDT supports 3 flexible configuration approaches. Choose what works best for you:

Method 1: GitHub Actions (Simplest)

Perfect for CI/CD pipelines. Configuration lives in GitHub Secrets.

Pros:

• ✅ No config files
• ✅ Secure secrets
• ✅ Quick setup

Cons:

• ❌ GitHub-only
• ❌ Can't deploy locally

# .github/workflows/deploy.yml
- name: Deploy
  env:
    DEPLOY_HOST: ${{ secrets.DEPLOY_HOST }}
    DEPLOY_USERNAME: ${{ secrets.DEPLOY_USERNAME }}
    DEPLOY_KEY_PATH: ${{ secrets.DEPLOY_SSH_KEY }}
    DEPLOY_REPO_URL: https://github.com/${{ github.repository }}.git
    DEPLOY_PATH: ${{ secrets.DEPLOY_PATH }}
  run: |
    composer global require veltix/zdt
    zdt deploy

See full example →

Method 2: Server Config (Recommended)

Store configuration in .env.deployment file on your server. Perfect for teams and multiple environments.

Pros:

• ✅ Deploy from anywhere
• ✅ Server-specific config
• ✅ No project files needed

Cons:

• ❌ Need server access
• ❌ Manual setup per server

Setup:

1. Create config on server:

   ssh user@your-server.com
   nano /var/www/myapp/shared/.env.deployment

2. Add your settings:

   DEPLOY_HOST=your-server.com
   DEPLOY_USERNAME=deploy
   DEPLOY_KEY_PATH=~/.ssh/id_rsa
   DEPLOY_REPO_URL=https://github.com/you/repo.git
   DEPLOY_PATH=/var/www/myapp
   DEPLOY_BRANCH=main

3. Deploy (simple!):

   - run: zdt deploy  # That's it! No env vars needed

See template →

Method 3: Project Config (Flexible)

Commit a deploy.php file to your repository. Great for complex logic or team workflows.

Pros:

• ✅ Versioned with code
• ✅ Custom logic
• ✅ Team-friendly

Cons:

• ❌ One more file to manage

Setup:

1. Add deploy.php to your project:

   curl -o deploy.php https://raw.githubusercontent.com/veltix/zdt/main/examples/deploy-project-env.php
   git add deploy.php
   git commit -m "Add deployment config"

2. Deploy:

   - run: zdt deploy  # Uses deploy.php from your repo

See example →

Hybrid Approach (Best of All!)

Use multiple methods together! Priority order:

1. Environment variables (highest - CI/CD overrides)
2. Server's .env.deployment (persists across deployments)
3. Project's deploy.php (versioned with code)

Example: Use .env.deployment on server for defaults, override with GitHub secrets for staging:

env:
  DEPLOY_BRANCH: staging  # Override branch for staging deploy
run: zdt deploy

Commands

# Deploy application
zdt deploy

# Rollback to previous release
zdt rollback

# Rollback to specific release
zdt rollback --release=20231202-143000

# List all releases
zdt releases:list

# Clean up old releases (keep 3 most recent)
zdt releases:cleanup --keep=3

# Initialize deployment structure on server
zdt deploy:init

Advanced Features

🏥 Health Checks

Validate your deployment succeeded with HTTP health checks. ZDT can ping a URL after activation and automatically rollback if it fails.

Configuration:

env:
  DEPLOY_HEALTH_CHECK_ENABLED: true
  DEPLOY_HEALTH_CHECK_URL: https://yourapp.com/health
  DEPLOY_HEALTH_CHECK_TIMEOUT: 30  # seconds

How it works:

1. Deploy completes and symlink switches
2. Health check pings your URL
3. If response is not 2xx, automatic rollback
4. If successful, continues with cleanup

Example Health Check Endpoint (Laravel):

// routes/web.php
Route::get('/health', function () {
    return response()->json(['status' => 'ok'], 200);
});

🔒 Deployment Locks

Prevent concurrent deployments that could corrupt your releases. ZDT automatically creates a lock file during deployment.

Features:

• Lock file at {DEPLOY_PATH}/.deploy.lock
• Prevents multiple simultaneous deployments
• Auto-removes stale locks (1 hour timeout)
• Always released even if deployment fails

No configuration needed - works automatically!

If a deployment is already running:

✗ Deployment failed: Another deployment is in progress.
  Lock file: /var/www/app/.deploy.lock (age: 120s, timeout in 3480s)

💾 Database Backups

Automatically backup your database before running migrations. Backups are compressed and stored with each release for easy restoration.

Configuration:

env:
  DEPLOY_DB_BACKUP_ENABLED: true
  DEPLOY_DB_CONNECTION: mysql        # or: pgsql, postgres, mariadb
  DEPLOY_DB_HOST: localhost
  DEPLOY_DB_PORT: 3306
  DEPLOY_DB_DATABASE: myapp
  DEPLOY_DB_USERNAME: dbuser
  DEPLOY_DB_PASSWORD: ${{ secrets.DB_PASSWORD }}
  DEPLOY_DB_KEEP_BACKUPS: 5          # Keep last 5 backups

Supported Databases:

• MySQL / MariaDB
• PostgreSQL

Backup Location:

/var/www/app/
├── backups/
│   ├── db-backup-20231215-143000.sql.gz
│   ├── db-backup-20231215-120000.sql.gz
│   └── db-backup-20231215-100000.sql.gz

Manual Restore:

# On server
cd /var/www/app/backups
gunzip db-backup-20231215-143000.sql.gz
mysql -u dbuser -p myapp < db-backup-20231215-143000.sql

📢 Deployment Notifications

Get notified about deployments via webhooks (Slack, Discord, etc.).

Configuration:

env:
  DEPLOY_NOTIFICATION_WEBHOOK: ${{ secrets.SLACK_WEBHOOK }}

Notifications sent for:

• 🚀 Deployment started
• ✅ Deployment successful
• ❌ Deployment failed
• ⏪ Deployment rolled back

Slack Webhook Setup:

1. Go to https://api.slack.com/apps
2. Create app → Incoming Webhooks → Add to Workspace
3. Copy webhook URL to GitHub Secrets
4. Done!

Discord Webhook Setup:

1. Server Settings → Integrations → Webhooks
2. Create Webhook → Copy URL
3. Add /slack to the end of URL
4. Add to GitHub Secrets

Example Slack Message:

🚀 Deployment started
Release: 20231215143000
Server: prod.example.com
Branch: main

Deployment Hooks

Run custom commands at different stages of deployment:

env:
  # After cloning repository
  DEPLOY_HOOKS_AFTER_CLONE: |
    composer install --no-dev --optimize-autoloader
    npm ci --production
    npm run build

  # Before activating new release
  DEPLOY_HOOKS_BEFORE_ACTIVATE: |
    php artisan migrate --force
    php artisan config:cache
    php artisan route:cache

  # After successful deployment
  DEPLOY_HOOKS_AFTER_ACTIVATE: |
    php artisan queue:restart
    php artisan cache:clear

Available hooks:

• DEPLOY_HOOKS_BEFORE_CLONE - Before cloning
• DEPLOY_HOOKS_AFTER_CLONE - After cloning, before activation
• DEPLOY_HOOKS_BEFORE_ACTIVATE - Before switching symlink
• DEPLOY_HOOKS_AFTER_ACTIVATE - After successful deployment
• DEPLOY_HOOKS_AFTER_ROLLBACK - After rollback

Note: Hooks that fail will abort deployment and trigger automatic rollback.

Server Directory Structure

/var/www/myapp/
├── current → releases/20231202150000/    # Symlink to active release
├── releases/
│   ├── 20231202143000/                   # Previous releases
│   ├── 20231202145000/
│   └── 20231202150000/                   # Current active
└── shared/
    ├── .env                               # Laravel env file
    ├── .env.deployment                    # ZDT config (optional)
    └── storage/                           # Shared storage

What's shared across releases:

• .env file (copied to each release)
• storage/ directory (symlinked)
• Custom paths you configure

Configuration Reference

Environment Variables

For Laravel Applications

Add these hooks for optimal Laravel deployments:

DEPLOY_HOOKS_AFTER_CLONE: |
  composer install --no-dev --optimize-autoloader

DEPLOY_HOOKS_BEFORE_ACTIVATE: |
  php artisan migrate --force
  php artisan config:cache
  php artisan route:cache
  php artisan view:cache

DEPLOY_HOOKS_AFTER_ACTIVATE: |
  php artisan queue:restart
  php artisan optimize

For Static Sites

DEPLOY_HOOKS_AFTER_CLONE: |
  npm i
  npm run build

Server Requirements

Your deployment server needs:

• SSH access with key-based authentication
• Git installed
• PHP 8.2+ (for PHP applications)
• Composer (for PHP dependencies)
• Node.js & NPM (for frontend builds)

Server Setup (One-time)

# Install dependencies (AlmaLinux/RHEL)
sudo dnf install git

# Or Ubuntu/Debian
sudo apt install git

# Create deployment user
sudo useradd -m -s /bin/bash deploy
sudo mkdir -p /var/www/myapp
sudo chown deploy:deploy /var/www/myapp

# Add SSH key
sudo -u deploy mkdir -p /home/deploy/.ssh
echo "your-public-key" | sudo -u deploy tee /home/deploy/.ssh/authorized_keys

Troubleshooting

Permission Errors

# Fix storage permissions
sudo chown -R deploy:nginx /var/www/myapp/shared/storage
sudo chmod -R 775 /var/www/myapp/shared/storage

Git Authentication (Private Repos)

For private repositories, your server needs access:

# On your server
ssh-keygen -t ed25519 -C "deploy@server" -f ~/.ssh/github_deploy
cat ~/.ssh/github_deploy.pub

Add the public key to: GitHub → Repo Settings → Deploy Keys

For public repositories, use HTTPS URL (no key needed):

DEPLOY_REPO_URL: https://github.com/user/repo.git

Examples

• Basic deployment - Simple GitHub Actions workflow
• Advanced workflow - Multiple environments, testing, notifications
• Server config - .env.deployment template
• Project config - deploy.php example

Contributing

Contributions welcome! Please:

1. Fork the repository
2. Create a feature branch
3. Write tests for your changes
4. Run vendor/bin/pint for code style
5. Run php zdt test to verify tests pass
6. Submit a pull request

Security

Found a security issue? Email security@veltix.sh instead of opening an issue.

Credits

Built with ❤️ using Laravel Zero

License

MIT License - see LICENSE.md

Deploy with confidence. Deploy with ZDT.