nginx tips: adding arbitrary output to a response
Geschrieben von Harald Lapp in nginx um 17:47
A while ago i wrote about how to use nginx as a proxy to do cookie based redirects. We use this functionality at work to provide easy access and view the progress of development of each developer.
I thought it would be nice to have the information, of which developers machine you currently have access to, right on the website. But i always disliked to put functionality to accomplish this inside the framework or even the app itself or have to install / modify some special configuration on each developers machine. I always wanted my proxy to do this kind of work. ... And nginx can.
It's the substitution module of nginx, that can replace arbitrary text in a http response. Nginx must be compiled with the option --with-http_sub_module configured.
The following rows show how to fill a variable $name with the name of the developer we are accessing the machine of. The statement sub_filter defines the search pattern as first parameter and the replace string as second parameter -- very easy, isn't it?
set $name ""
if ($http_cookie ~* "(; )?devredirect=([^;]+)") {
set $name $2;
}
sub_filter "</body>" "<div style='position: fixed;
left: 0; top: 0; font-weight: bold; padding: 5px; color: #000;
background-color: rgb(235,58,0);'>devredirect: ${name}</div>
</body>";
The following rows show the part of the proxy configuration with the inserted substitution filter:
server {
listen 80;
server_name .clipdealer.devcenter.int;
proxy_redirect off;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
location / {
set $name ""
if ($http_cookie ~* "(; )?devredirect=([^;]+)") {
set $name $2;
}
sub_filter "</body>" "<div style='position: fixed;
left: 0; top: 0; font-weight: bold; padding: 5px;
color: #000; background-color: rgb(235,58,0);'>
devredirect: ${name}</div></body>";
if ($http_cookie ~* "(; )?devredirect=harald") {
proxy_pass http://10.0.0.20;
break;
}
...
}
....
}
