Nginx: dynamic proxy from url to subdomain - redirect

Question

I'm trying to write a nginx conf to dynamically redirect a url to a webapp, based on the uri. I use proxypass directive.
For example, I want redirect http://www.example.com/clientname/ to http://clientname.internaldomain.local/webapp
So far, I only succeded replacing new host, but the uri is broken because I can't split it. (Now I can't even replace the host, dunno why ...)
Here is my actual non working conf:
server {
resolver 192.168.137.71;
listen 80;
server_name tomservpa1;
location ~ (^\/(.*)\/) {
set $ccehost $2;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Host $host;
proxy_set_header X-Forwarded-Server $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_pass http://$ccehost.internaldomain.local:9780/webapp/$new_request_uri;
proxy_redirect off;
proxy_set_header Host $host;
}
}
Did someone already do something like that ?
Thanks.

Answer 1

You can use named captures in the location directive is avoid scope and ambiguity issues. For example:
location ~ ^/(?<ccehost>[^/]+)/(?<new_request_uri>.*)$ {
rewrite ^ /webapp/$new_request_uri break;
...
proxy_pass http://$ccehost.internaldomain.local:9780;
...
}

Answer 2

this is the way to do it: (set in production)
location ~* ^/(?<ccehost>.*)/(.*) {
proxy_intercept_errors on;
proxy_cookie_path ~*^/.* /;
proxy_set_header X-Forwarded-For $remote_addr;
proxy_set_header Host $host;
proxy_set_header X-Forwarded-Host $host;
proxy_set_header X-Forwarded-Server $host;
proxy_pass http://$ccehost.app.ptf:8080/app/$2;
}