ngx_http_server_redirect_module

Table of Contents

• ngx_http_server_redirect_module
  • Table of Contents
  • Description
  • Status
  • Installation
  • Synopsis
    • Basic Redirection
    • Conditional Redirection
  • Configuration
    • Directive: server_redirect
    • Directive: schedule_redirect
    • Variable: $server_redirect_original_host
  • Author
  • License

---

Description

The ngx_http_server_redirect_module is a custom nginx module designed to facilitate dynamic server redirection based on configurable rules. It allows users to redirect incoming requests to different servers conditionally.

Status

This Nginx module is currently considered experimental. Issues and PRs are welcome if you encounter any problems.

Installation

To use theses modules, configure your nginx branch with --add-module=/path/to/ngx_http_server_redirect_module.

Synopsis

Basic Redirection

Redirect all requests to newserver.com unconditionally.

http {
    server {
        listen 80;
        server_name example.com;

        server_redirect newserver.com;

        location / {
            proxy_pass http://newserver.com;
        }
    }

    server {
        listen 80;
        server_name newserver.com;

        # You can get original host from this variable.
        add_header x-original-host $server_redirect_original_host;

        location / {
            proxy_pass http://upstream.com;
        }
    }
}

Conditional Redirection

Redirect requests based on the presence of a specific header.

http {
    server {
        listen 80;
        server_name example.com;

        # Redirect if request has 'X-Redirect' header and value is not 0 or empty.
        server_redirect newserver.com if=$http_x_redirect;

        # You can use ngx_http_var_module to generate judgment variables based on conditions.
        # https://git.hanada.info/hanada/ngx_http_var_module
        # var $is_ipv6 if_find $remote_addr :;
        # server_redirect newserver.com if=$is_ipv6;

        # This module takes effect after the real_ip module,
        # Therefore, the real_ip module's directives will take effect on the server before server redirect.
        # real_ip_header x-client-ip;

        location / {
            proxy_pass http://newserver.com;
        }
    }

    server {
        listen 80;
        server_name newserver.com;

        # You can get original host from this variable.
        add_header x-original-host $server_redirect_original_host;

        location / {
            proxy_pass http://upstream.com;
        }
    }
}

Schedule Redirection

Redirect the current request to another server from the first request path. If request http://example.com/newserver.com/test?arg=1, it will be redirect to http:///newserver.com/test?arg=1. This process is internal and no 302 redirection will occur.

http {
    server {
        listen 80;
        server_name example.com;

        # Enable schedule redirection.
        schedule_redirect on;

        # Requests will not arrive here unless the first path in the request path does not exist or the host in the first path is invalid.
        return 400 "request path invalid";
    }

    server {
        listen 80;
        server_name newserver.com;

        # You can get original host from this variable.
        add_header x-original-host $server_redirect_original_host;

        location / {
            proxy_pass http://upstream.com;
        }
    }
}

Configuration

Directive: server_redirect

Syntax: server_redirect target_host [if=condition]

Default: -

Context: server

Redirect the current request to another server. The target server must have the same listening port as the current server.

The target host should be a specific host name just like the host in the request header. Even if the target server you want to redirect to is a wildcard domain name or a regular expression.

If the target server cannot be found, it will be redirected to the default server.

The if parameter enables conditional redirection. A request will not be redirected if the condition evaluates to “0” or an empty string. In addition, you can also use the form of if!= to make negative judgments.

Here is an example:

server_redirect newserver.com if=$http_server_redirect;

This example redirects requests to newserver.com if the Server-Redirect header has value and value is not 0.

Directive: schedule_redirect

Syntax: schedule_redirect on | off

Default: schedule_redirect off

Context: server

Redirect the current request to another server from the first request path.

If enabled, when accessing http://a.com/b.com/, the request will be redirected to http://b.com/. If the target server cannot be found, it will be redirected to the default server.

When server_redirect directive exists and meets the redirection conditions, server_redirect will be executed first.

If the request path does not have the first path (such as the home page), no redirection will be made.

After redirection, even $request_uri will be cleared of the first path. You can only find the original request path in the request line variable $request.

Variable: $server_redirect_original_host

Keeps the original value of variable $host before redirection occurs.

Author

Hanada [email protected]

License

This Nginx module is licensed under BSD 2-Clause License.