Nginx reverse proxy installation script

#!/bin/bash

# Error handling
set -e
set -o pipefail

error_exit() {
    echo "Error: $1"
    exit 1
}

echo "Welcome to the Nginx reverse proxy installation script."

# Check if Nginx is already installed
if dpkg -l nginx | grep -q '^ii'; then
    read -p "Nginx is already installed. Do you want to add a new configuration? (y/n): " add_config
    if [[ "$add_config" != "y" && "$add_config" != "Y" ]]; then
        echo "Nginx configuration skipped."
        exit 0
    fi
else
    read -p "Do you want to install Nginx as a reverse proxy? (y/n): " install_nginx
    if [[ "$install_nginx" != "y" && "$install_nginx" != "Y" ]]; then
        echo "Nginx installation skipped."
        exit 0
    fi

    # Update package lists
    echo "Updating package lists..."
    sudo apt update || error_exit "Failed to update package lists."

    # Install Nginx
    echo "Installing Nginx..."
    sudo apt install -y nginx || error_exit "Failed to install Nginx."
fi

# Check if Certbot is already installed
if dpkg -l certbot | grep -q '^ii'; then
    echo "Certbot is already installed."
else
    read -p "Do you want to install Certbot for managing SSL certificates? (y/n): " install_certbot
    if [[ "$install_certbot" != "y" && "$install_certbot" != "Y" ]]; then
        echo "Certbot installation skipped."
        exit 0
    fi

    # Install Certbot
    echo "Installing Certbot..."
    sudo apt install -y certbot python3-certbot-nginx || error_exit "Failed to install Certbot."
fi

# Prompt user for website name
read -p "Enter the domain name for the website (e.g., example.com): " domain_name

# Check if config file already exists
conf_file="/etc/nginx/sites-available/${domain_name}"
if [ -f "$conf_file" ]; then
    read -p "A configuration file for $domain_name already exists. Do you want to overwrite it? (y/n): " overwrite_conf
    if [[ "$overwrite_conf" == "y" || "$overwrite_conf" == "Y" ]]; then
        echo "Overwriting existing configuration file..."
    else
        echo "Keeping current configuration file. Exiting..."
        exit 0
    fi
fi

# Configure Nginx as a reverse proxy for PHP-FPM
cat <<EOF | sudo tee "$conf_file"
server {
    listen 80;
    listen [::]:80;

    server_name ${domain_name};

    root /var/www/${domain_name}/public; # Change to your website's document root

    index index.php index.html index.htm;

    location / {
        try_files \$uri \$uri/ /index.php?\$query_string;
    }

    location ~ \.php$ {
        include snippets/fastcgi-php.conf;
        fastcgi_pass unix:/var/run/php/php8.1-fpm.sock; # Change to match your PHP version
    }

    location ~ /\.ht {
        deny all;
    }
}
EOF

# Create a symbolic link to enable the site
sudo ln -sf "$conf_file" /etc/nginx/sites-enabled/

# Test Nginx configuration
sudo nginx -t || error_exit "Nginx configuration test failed."

# Reload Nginx to apply changes
sudo systemctl reload nginx || error_exit "Failed to reload Nginx."

# Obtain SSL certificate using Certbot
echo "Obtaining SSL certificate using Certbot..."
sudo certbot --nginx -d "$domain_name" || error_exit "Failed to obtain SSL certificate using Certbot."

echo "Nginx has been successfully configured as a reverse proxy for ${domain_name}, and SSL certificate has been obtained."