Rewrite a subdomain to a backend proxy whith nginx - nginx

Question

if have a subdomain on my nginx webserver configuration: sub.mydomain.com
and i have a backend server which listen on port 5000: http://127.0.0.1:5000
is it possible to pass all subdomain calls to the backend?
Like: https://sub.mydomain.com/list to http://127.0.0.1:5000/sub/list
This should work with all methods: POST, PUT, GET, DELETE
UPDATE:
when i call my server: https://mysubdomain.mydomain.com
with the following configuration:
upstream http_backend {
server 127.0.0.1:5000;
}
server_name ~^(?<subdomain>[^.]+)\.mydomain\.com;
This does not work (error: 404):
location / {
proxy_pass http://http_backend/$subdomain/;
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;
proxy_set_header X-Forwarded-Proto https;
}
This works fine:
location / {
proxy_pass http://http_backend/mysubdomain/;
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;
proxy_set_header X-Forwarded-Proto https;
}
When i log the $subdomain variable in the access_log, it seems to be correct.
nginx version: nginx/1.9.15

Answer 1

To pass all subdomains you need to set it in server name by putting dot before domain.
server_name .mydomain.com;

Answer 2

Yes, you can use variables in proxy_pass. And you can extract part of domain using regexp server name.
server {
server_name ~^(?<sub>[^.]+)\.example\.com;
# now subdomain of example.com placed to $sub
# please, note, this rule do not work for http://example.com
location / {
proxy_pass http://127.0.0.1:5000/$sub/;
# Path part of proxy_par URI will replace path
# part of location directive (so / -> /$sub/, /xxxx/ -> /$sub/xxxx/)
}
}
Thats all :)

Answer 3

It seems nginx does not add the $uri to the proxy_pass if i use the $subdomain variable.
The following solution works:
location / {
proxy_pass http://http_backend/$subdomain/$uri;
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;
proxy_set_header X-Forwarded-Proto https;
}