node_js_server_with_mysql_check

#!/bin/bash
# setup.sh - Main setup script
exec > >(tee /var/log/setup.log) 2>&1
echo "Starting Node.js application setup..."

# Update system and install dependencies
apt-get update
apt-get upgrade -y
apt-get install -y netcat-openbsd mysql-client

# Install Node.js
curl -fsSL https://deb.nodesource.com/setup_18.x | bash -
apt-get install -y nodejs

# Create script directory
mkdir -p /usr/local/bin

# Copy the MySQL check script to proper location
cat > /usr/local/bin/check-mysql.sh << 'EOL'
#!/bin/bash
DB_HOST="$DB_PRIVATE_IP"
DB_PORT=3306
MAX_RETRIES=30
RETRY_INTERVAL=10

check_mysql() {
  nc -z "$DB_HOST" "$DB_PORT"
  return $?
}

retry_count=0
while [ $retry_count -lt $MAX_RETRIES ]; do
  if check_mysql; then
    echo "Successfully connected to MySQL at $DB_HOST:$DB_PORT"
    exit 0
  fi
  echo "Attempt $((retry_count + 1))/$MAX_RETRIES: Cannot connect to MySQL at $DB_HOST:$DB_PORT. Retrying in $RETRY_INTERVAL seconds..."
  sleep $RETRY_INTERVAL
  retry_count=$((retry_count + 1))
done

echo "Failed to connect to MySQL after $MAX_RETRIES attempts"
exit 1
EOL

chmod +x /usr/local/bin/check-mysql.sh

# Wait for environment variable to be set
max_attempts=30 
attempt=0
while [ -z "$DB_PRIVATE_IP" ]; do
    if [ $attempt -ge $max_attempts ]; then
        echo "Timeout waiting for DB_PRIVATE_IP to be set"
        exit 1
    fi
    echo "Waiting for DB_PRIVATE_IP environment variable..."
    attempt=$((attempt + 1))
    sleep 10
    # Source the environment file only once per iteration
    source /etc/environment
done
echo "DB_PRIVATE_IP is set to: $DB_PRIVATE_IP"

# Wait for MySQL server to be ready
echo "Waiting for MySQL server to be ready..."
sleep 120
echo "Creating MySQL Connectivity Check Service"

# Install systemd service
cat > /etc/systemd/system/mysql-check.service << 'EOL'
[Unit]
Description=MySQL Connectivity Check Service
After=network.target
Wants=network.target

[Service]
Type=simple
EnvironmentFile=/etc/environment
ExecStart=/usr/local/bin/check-mysql.sh
Restart=on-failure
RestartSec=30
StandardOutput=append:/var/log/mysql-check.log
StandardError=append:/var/log/mysql-check.log

[Install]
WantedBy=multi-user.target
EOL

# Reload systemd and start service
systemctl daemon-reload
systemctl enable mysql-check
systemctl start mysql-check
echo "MySQL check service has been started. You can check the status with: systemctl status mysql-check"