Conditional Location routing - nginx - nginx

Question

Issue:
I have two applications served by one nginx 1.5.5 webserver on one domain, www.domain.com.
Because they both listen on the same locations I added a header of APP = ONE or TWO which I set when the application is first called. Example below.
location ^/APPONE {
proxy_pass http://APPONE;
add_header APP ONE;
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 ^/APPTWO {
proxy_pass http://APPTWO;
add_header APP TWO;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
Due to poor application design, the applications both request the below locations not using the application name as a docroot. Like the example below.
location ~ ^/(framerwork1/|framerwork2/|framerwork3/) {
proxy_pass http://APPONE;
add_header APP ONE;
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 ~ ^/(framerwork1/|framerwork2/|framerwork3/) {
proxy_pass http://APPTWO;
add_header APP TWO;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
So, I added the APP ONE or TWO header to separate the two, but my if statements to proxy them based on the header is not being accepted by Nginx. Example Below.
if ($http_host ~ 'APP=ONE') {
location ~ ^/(framerwork1/|framerwork2/|framerwork3/) {
proxy_pass http://APPONE;
add_header APP ONE;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
if ($http_host ~ 'APP=TWO') {
location ~ ^/(framerwork1/|framerwork2/|framerwork3/) {
proxy_pass http://APPTWO;
add_header APP TWO;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
Question: How can I proxy these two application successfully based on the header? Please note, I am unable to use a different server block or domain. They must be the same.
Thanks in advance.

Answer 1

Ok, so a request is coming in to www.domain.com/APPONE . You don't say exactly what is being requested through the URL www.domain.com/framerwork1/ but lets imagine it's an image that is required by the page served at /APPONE as that is simple to understand.
When you are setting the header through 'add_header' it is being set in the second array in "Client" -> Nginx -> PHP Proxy.
When the client then makes the request to the image at www.domain.com/framerwork1/ it has no idea that you are hoping to have a header set to be able to determine if the image was requested by APPONE, or something else.
Even if you set the header on the response for www.domain.com/APPONE clients do not blindly echo headers sent to them back to server for subsequent requests.
Or to put it bluntly, I think you've misunderstood where the headers are being passed, and that there isn't really a way to determine what application is making a request to the /framerwork1/ URL like that. You have to do this either via separate domain names (or sub-domain) or by doing it inside your application with things like looking at which application the user is logged into.