nginx module - Developer documentation | Documentation

nginx module

We provide an nginx module, which exposes redirection.io right in your nginx configuration. Using this module is one of the advised ways of integrating redirection.io in your infrastructure.

We also provide an Apache module for Apache users.

As an alternative to the deployment using the "reverse proxy" mode, the redirection.io nginx module is a quick way to integrate redirection.io in your existing infrastructure. This dynamic module just hooks in the nginx request and response loop, and synchronously queries a tcp API of the locally installed agent whenever a request arrives. When an incoming HTTP(s) request arrives, it is handled by the nginx webserver, which redirection.io's native module hooks in, in a very fast and performant way:

Please note that the nginx module requires a redirection.io agent instance to be available on your infrastructure, so please also setup the redirection.io agent.

Installing the module

Debian and APT-based distributions

If you use a Debian or APT-based Linux distribution and want to install libnginx-mod-redirectionio, please use the following commands:

  1. Select your distribution

    • Debian 13 (Trixie)
    • Debian 12 (Bookworm)
    • Debian 11 (Bullseye)
    • Ubuntu 24.04 LTS (Noble Numbat)
    • Ubuntu 22.04 LTS (Jammy Jellyfish)

  2. Install the apt-transport-https package:

    sudo apt-get install apt-transport-https

  3. Import our apt repository key:

    sudo mkdir -p /etc/apt/keyrings
wget -qO- https://packages.redirection.io/gpg.key | sudo tee /etc/apt/keyrings/redirectionio-archive-keyring.asc

  4. Add our Debian url:

    echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/redirectionio-archive-keyring.asc] https://packages.redirection.io/deb/stable/3 trixie main" | sudo tee -a /etc/apt/sources.list.d/packages_redirection_io_deb.list > /dev/null

  5. Update the apt cache and install redirection.io's nginx module:

    sudo apt update && sudo apt install libnginx-mod-redirectionio

  6. Once the module is installed, restart the nginx service, for instance:

    sudo systemctl restart nginx

You're done! redirection.io is installed, up and running. You can go on with redirection.io's nginx configuration and should see some logs within minutes 🎉

Red Hat and RPM-based distributions

Our nginx module is available for Centos 7, Centos 8, RHEL 7, RHEL 8 up to the release 2.8.0. From the release 2.9.0 and later, only Centos 9 stream is supported. However, you may still compile the redirection.io nginx module for your distribution

If you use a Red Hat/CentOS-like Linux distribution and want to install libnginx-mod-redirectionio, please use the following commands:

  1. Import the signature key:

    sudo rpm --import https://packages.redirection.io/gpg.key

  2. Add our RPM repository:

    sudo yum-config-manager --add-repo https://packages.redirection.io/rpm/stable/3/centos_9

  3. Install redirection.io's nginx module:

    sudo yum install libnginx-mod-redirectionio

  4. Once the module is installed, restart the nginx service, for instance:

    sudo systemctl restart nginx

Ansible role

A redirectionio.nginx_module Ansible role is available. You may install it using Ansible Galaxy:

ansible-galaxy install redirectionio.nginx_module

Basically, this role installs the redirection.io nginx module and makes sure you use the right repository locations, depending on your host operating system.

Configuration

Enabling the redirection.io is as simple as declaring the project key in the Virtualhost or configuration node where you want to enable redirection.io.

You can find the project key in the "instances" screen of the manager (click on the "Setup on your website" > "Setup on your infrastructure" button).

For instance, this can be in your main server directive:

http {
    ...
    redirectionio_project_key SOME_PROJECT_KEY_HERE;
    ...
}

Or in a Virtualhost:

server {
    server_name example.org;
    root /path/to/root;

...
    redirectionio_project_key SOME_PROJECT_KEY_HERE;
    ...
}

Or even in a location block:

server {
    server_name example.org;
    root /path/to/root;

...

location /some-path/ {
        redirectionio_project_key SOME_PROJECT_KEY_HERE;
    }
    ...
}

The redirectionio_project_key can either be double-quoted or not (eg., SOME_PROJECT_KEY_HERE or "SOME_PROJECT_KEY_HERE").

Module configuration directives

The libnginx-mod-redirectionio enables several configuration directives, which can be used wherever the redirectionio_project_key is used:

redirectionio

This directive enables or disables redirection.io for requests matching the current context. By default, redirection.io is disabled, but is automatically enabled when the directive redirectionio_project_key is set in a node of the configuration.

Using redirectionio off can hence be useful to disable redirection.io in a particular location:

server {
    server_name example.org;
    root /path/to/root;
    redirectionio_project_key SOME_PROJECT_KEY_HERE;

...

location /some-path/ {
        redirectionio off;
    }
    ...
}

redirectionio_project_key

Sets the redirection.io project key to use for requests matching the current context. When set, this directive automatically turns the redirectionio directive on.

redirectionio_logs

This directive enables or disables logs collection for the current matching context (however, please note that logs will only be sent if both the redirectionio directive and redirectionio_logs are set to on. In other terms, setting redirectionio_logs to on with redirectionio set to off won't collect any logs).

redirectionio_pass

This directive specifies the location of the redirectionio-agent that the nginx module must use for matching requests. In a traditional setup, the agent is only available at 127.0.0.1:10301. If you expose the agent through a file, then the value of the redirectionio_pass directive can, for instance, be of the form unix:///var/run/redirectionio.sock.

This directive also allows to set some connection pool management options:

redirectionio_pass 127.0.0.1:10301 min_conns=0 keep_conns=10 max_conns=10 timeout=100;

All the settings min_conns, keep_conns, max_conns and timeout are optional:

For example, with min_conns=1 keep_conns=10 max_conns=100 timeout=50:

redirectionio_scheme

This directive allows to force the scheme to use when matching the request. This is useful if you have defined rules using a URL trigger with an absolute URL value (containing a scheme, a domain name, etc.), but you want to use the same rules in a VirtualHost with another scheme.

Imagine, for example, a VirtualHost listening https traffic only, using a project in which rules are defined using the http:// scheme: URLs would never be matched, as no rule uses the https:// scheme. In this case, setting the redirectionio_scheme value to http will force the module to match with this scheme, not the real request scheme.

redirectionio_host

This directive allows to force the host to use when matching the request. This is useful if you have defined rules using URL triggers with absolute URL values (containing a scheme, a domain name, etc.), and your VirtualHost uses another hostname.

redirectionio_add_rule_ids_header

If this setting is enabled, a response header named X-RedirectionIo-RuleIds will be added to the response. Its value will contain the list of the redirection.io rule ids applied to this response, separated by the ; character.

redirectionio_set_header

This directive allows to pass the request to the redirection.io module by adding a request header filled with a given value. The value passed to the header can be a nginx variable, eg.: 

redirectionio_set_header X-GeoIP-Country-Code $geoip_data_country_code;

This can be useful to pass variables from the nginx context to the redirection.io agent, that can be used in redirection rules using the request header trigger.

redirectionio_trusted_proxies

This directive is used by the module to restrict which proxies are trusted before evaluating the X-Forwarded-* headers. This is in particular useful when using the IP Address trigger, in order to ensure that the evaluated IP address is valid and has not been forged.

The nginx module is opensource and available on our github account.

Questions and answers & troubleshooting

Are there any drawbacks to using the nginx module instead of the "reverse proxy" mode?

While this approach is interesting - because it means few changes to the infrastructure layout and the requests flow in your stack - it can be sometimes challenging to setup:

This is why we usually recommend to rather use the reverse proxy mode. However, the nginx module is a perfectly convenient, supported, and fully tested way to use redirection.io if you wish so.

The module cannot be loaded

We distribute our nginx module for many distributions, which should cover most of the production cases. However, there is one limitation: the packages that we propose will only work with the default nginx version provided by the distribution. To load a nginx module, it must be binary compatible with the version of nginx installed. If you try to load the redirection.io nginx module with an incompatible version of nginx, you should get error messages such as:

nginx: [emerg] module "/usr/share/nginx/modules/ngx_http_redirectionio_module.so" version 1018000 instead of 1024000 in /etc/nginx/modules-enabled/50-mod-http-redirectionio.conf:1

So, if you installed a more recent version of nginx - either by compiling it yourself, or by using a third-party packages repository (for example the nginx packages repository) - then the module that we provide in our own packages repository is not binary-compatible with the version of nginx that you are using. In this case, you will have to compile the redirection.io nginx module yourself, as described in the chapter " Using the nginx module with a non-standard nginx install" below. If you are fluent with Docker, this compilation process is also available as a Dockerfile on our Github account.

The nginx reload / restart command does not work and errors unknown directive "redirectionio_project_key"

If nginx fails to reload and complains about an unknown directive redirectionio_project_key, this may indicate that the nginx module has not been correctly loaded in nginx. Please check that your main nginx configuration file (usually /etc/nginx/nginx.conf) contains a line to include enabled nginx modules (eg. include /etc/nginx/modules-enabled/*.conf;). If this line is missing, you may force loading the module by adding the following line in /etc/nginx/nginx.conf:

load_module modules/ngx_http_redirectionio_module.so;

Then, restart nginx (again), and it should be fine.

The module redirects to a wrong domain, or to a wrong port

In some production setups, the nginx server is not the first node of the infrastructure - there can be a Varnish, an Envoy proxy, a front nginx configured as a reverse proxy, etc. By default, nginx will generate a redirection Location with the domain name and port number it received the request with. This means that, if the redirection.io nginx module runs in a nginx server listening in http (not https) on the domain internal on port 8080, the redirections Location header will be of the form Location: http://internal:8080, which is obviously not what you want. In those cases, you may add the absolute_redirect off; directive in the VirtualHost where the redirection.io module is enabled:

server {
    listen 8080;
    server_name internal;
    root /path/to/root;

absolute_redirect off;

...
    redirectionio_project_key SOME_PROJECT_KEY_HERE;
    ...
}

This will prevent nginx to rewrite/set the scheme, host and port in redirection targets using relative locations. This won't affect the redirection rules that you created to other external domains.

Dynamically choose the project key to use

You may need to manage several websites under the same nginx VirtualHost, while still wanting to keep separate redirection.io projects (for organizational reasons, to delegate the permissions to the right teams, etc.) In this case, a first solution can be to use a nginx variable to dynamically define the redirection.io project key to use. In the http section of the nginx configuration, define the $project_key variable:

http {
    ...

map $http_host $project_key {
        default 'KEY TO BE USED BY DEFAULT';
        'example.com' 'KEY FOR THE example.com PROJECT';
        'second-domain.com' 'KEY FOR THE SECOND PROJECT';
        'fr.example.com' 'KEY FOR THE fr.example.com SUB-DOMAIN PROJECT';
    }
}

And, in the VirtualHost, use this variable:

server {
    listen 80 default_server;
    listen [::]:80 default_server;
    server_name _;
    root /path/to/root;

...

redirectionio_project_key $project_key;
}

This setup allows to:

server {
    listen 80 default_server;
    listen [::]:80 default_server;
    server_name _;
    root /path/to/root;

# default project key
    redirectionio_project_key 'KEY TO BE USED BY DEFAULT';

location /fr/ {
      redirectionio_project_key 'KEY FOR THE fr region PROJECT';
    }

location /uk/ {
      redirectionio_project_key 'KEY FOR THE uk region PROJECT';
    }

location /us/ {
      redirectionio_project_key 'KEY FOR THE us region PROJECT';
    }

...
}

If the VirtualHost already contained some directives in a / location, that you still want to use, then you have to replicate these directives in each of the location blocks.