24 Nov 15 HTTP request header from a query string parameter on apache reverse proxy

Suppose you have a apache httpd server working as a reverse proxy. Now suppose that this server has to set a HTTP request header called “token” to be attached to every request made to the backends, and that the header’s value must be copied from a query string parameter called “querytoken”.

This can be simply done with the help of mod_headers + mod_rewrite.

RewriteEngine On
RewriteCond %{QUERY_STRING} (?:^|&)querytoken=([^&]+)
RewriteRule (.*) - [E=QS_TOKEN:%1]

RequestHeader set token %{QS_TOKEN}e env=QS_TOKEN
ProxyPass / http://your_backend/

Will your external client make a request like this:

GET /?querytoken=somestuff HTTP/1.0
Host: example

The request header that apache will do to the backend will be something like this:

GET /?token=somestuff HTTP/1.1
Host: 127.0.0.1:1234
token: somestuff
X-Forwarded-For: 127.0.0.1
X-Forwarded-Host: example
X-Forwarded-Server: myserver.linux
Connection: Keep-Alive

The request header “token” with value “somestuff” is added to the request made to the backend.