Automate Git Pull and Application Restart for Deployments

#!/bin/bash
# Script to pull latest code and restart a systemd service for web application deployments

# Configuration
APP_DIR="/var/www/mywebapp" # Root directory of your web application
GIT_BRANCH="main"           # The Git branch to pull from (e.g., main, master, production)
SERVICE_NAME="mywebapp.service" # The name of your systemd service (e.g., nginx, apache2, nodeapp.service)

echo "========================================"
echo "Starting deployment script for $APP_DIR"
echo "========================================"

# Navigate to the application directory
cd "$APP_DIR" || {
  echo "Error: Application directory '$APP_DIR' not found or not accessible."
  echo "Please check the APP_DIR variable and directory permissions."
  exit 1
}

echo "Current working directory: $(pwd)"

# Pull latest changes from Git
echo "Pulling latest changes from Git branch '$GIT_BRANCH'..."
# 'git reset --hard' ensures a clean state before pulling, discarding local changes
# 'git pull origin $GIT_BRANCH' fetches and merges the latest changes
git reset --hard origin/"$GIT_BRANCH" && git pull origin "$GIT_BRANCH" || {
  echo "Error: Git pull failed. Please check repository access and branch name."
  exit 1
}

echo "Git pull completed successfully."

# Restart the application service
echo "Restarting service '$SERVICE_NAME'..."
sudo systemctl restart "$SERVICE_NAME" || {
  echo "Error: Failed to restart service '$SERVICE_NAME'."
  echo "Please check the service name and 'sudo' permissions."
  exit 1
}

echo "Service '$SERVICE_NAME' restarted successfully."

echo "========================================"
echo "Deployment script finished successfully!"
echo "========================================"