When handling redirects in Nginx, we often need to reconstruct the original request's protocol, domain, and port while modifying only the path portion. The standard Nginx variables like $scheme, $host, and $port work well individually, but concatenating them requires special handling.


The most straightforward approach is to combine the variables manually in your location block:

location = /login.htm {
    return 301 $scheme://$host:$server_port/login;
}

Note we use $server_port instead of $port since $port shows the client's port in some cases.


To avoid showing redundant port numbers (like :443 for HTTPS), we can use a more sophisticated approach:

map $scheme $port_suffix {
    http    ":80";
    https   ":443";
    default "";
}

server {
    ...
    set $show_port $server_port;
    if ($server_port = $port_suffix) {
        set $show_port "";
    }
    if ($show_port != "") {
        set $show_port ":$show_port";
    }

    location = /login.htm {
        return 301 $scheme://$host$show_port/login;
    }
}


If you're okay with the browser potentially following redirects to different host variations (www vs non-www), you could simplify to:

location ~* \.htm$ {
    return 301 $scheme://$host$uri;
}


Remember these important details:
- $host includes the port if it's non-standard
- $http_host preserves the exact Host header
- For proxy scenarios, you might need $proxy_host


Here's a full example handling various cases:

server {
    listen 80;
    listen 443 ssl;
    server_name example.com;

    # Port normalization
    set $port_display "";
    if ($server_port !~ "^(80|443)$") {
        set $port_display ":$server_port";
    }

    # Redirect .htm to clean URLs
    location ~* ^(.+)\.htm$ {
        return 301 $scheme://$host$port_display$1;
    }

    # Other configurations...
}

When implementing redirects in Nginx, we often need to maintain the original request's protocol, domain, and port while only modifying the path. The common approach using $scheme://$host:$port works but feels verbose. Let's explore more elegant solutions.

The most reliable method is concatenating the individual variables:

return 301 $scheme://$host:$server_port$request_uri;

Key points about this approach:

• $server_port is more accurate than $port as it reflects the actual server port
• Works consistently for both HTTP (80) and HTTPS (443) default ports
• Preserves the original request's scheme (http/https)

For more complex deployments, consider this pattern:

server {
    listen 80;
    listen 443 ssl;
    server_name example.com;
    
    location /old-path {
        return 301 https://$host$request_uri;
    }
}

Notice we omit the scheme when using HTTPS to prevent double redirects.

When dealing with non-standard ports or load balancers:

map $http_x_forwarded_proto $real_scheme {
    default $scheme;
    "https" "https";
}

server {
    # ...
    return 301 $real_scheme://$host:$server_port/new-path;
}

This accommodates:

• Proxy headers (X-Forwarded-Proto)
• Custom port configurations
• Cloud deployments

Always prefer return over rewrite for simple redirects:

# Good
return 301 $scheme://$host/new-path;

# Avoid
rewrite ^/old-path /new-path permanent;

The return directive is more efficient as it doesn't trigger regex processing.

Here's a complete implementation for removing file extensions:

server {
    listen 80;
    server_name www.example.com;
    
    location ~ ^/(.*)\.htm$ {
        return 301 $scheme://$host/$1;
    }
}

This captures the path before .htm and redirects to the clean URL.