How To Preserve Original URL With Nginx Proxy_Pass?

Using proxy_set_header Directive

The proxy_set_header directive helps preserve the original URL when using Nginx's proxy_pass. This directive lets you set or change request header fields sent to the proxied server.

To keep the original URL, you can use proxy_set_header to set the Host header. The Host header tells the proxied server which domain name to use for processing the request. Setting this header to the original host makes sure the proxied server gets the right information about the original request.

Here's how proxy_set_header helps preserve the original URL:

1. It sets the Host header to the $host variable, which has the original request's host name.
2. This makes sure your Thin or Unicorn app server gets the correct host information.
3. With the right host information, your application can handle routing and process the request as if it came directly from the client.

By using proxy_set_header with proxy_pass, you can forward requests to your application server while keeping the original URL structure. This fixes the issue of Nginx changing the URL during proxying, allowing your application to work as expected.

server {
    listen 80;
    server_name example.com;

    location / {
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_pass http://backend_server;
    }
}

Configuring Nginx

To implement the solution and keep the original URL when using Nginx's proxy_pass, follow these steps to change your Nginx configuration:

1. Open your Nginx configuration file. It's usually at /etc/nginx/nginx.conf or /etc/nginx/sites-available/your_site_config.

2. Find the server block for your website.

3. In the server block, find or create a location block that matches the path you want to proxy.

4. Add the proxy_set_header directive to set the Host header.

5. Include the proxy_pass directive to send requests to your backend server.

Here's an example configuration block:

server {
    listen 80;
    server_name yourdomain.com;

    location / {
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;

        proxy_pass http://your_backend_server;
    }
}

In this configuration:

• proxy_set_header Host $host; keeps the original host name.
• proxy_set_header X-Real-IP $remote_addr; sends the client's IP address.
• proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; adds the client's IP to the X-Forwarded-For header.
• proxy_set_header X-Forwarded-Proto $scheme; sends the original protocol (http or https).
• proxy_pass http://your_backend_server; sends requests to your backend server.

Replace yourdomain.com with your actual domain name and http://your_backend_server with the address of your Thin or Unicorn app server.

After making these changes, save the configuration file and restart Nginx to apply the new settings.

nginx -t