NGINX proxy URL to different subdomain - nginx

Question

I am working on a website available in different countries/regions. For SEO reasons we would like to use subdirectories per country for the url. So we have example.com as main domain. When you navigate to example.com/jp/ you would be shown the Japanese version.
Now for technical reasons (the usage of the Domains module for Drupal to be exact) I would like to use a subdomain to place the website on. Lets say jp.example.com. To the outside world, people would navigate to /jp/ but NGINX returns jp.example.com
Both jp.example.com and example.com are the same website, but because of the domains module it shows different content. This means they share their codebase and theoretically their virtual host configuration. I have been trying many things, but ended up with this:
server {
listen 80;
server_name www.example.com jp.example.com;
root /var/www/example.com;
index index.php index.html index.htm;
location /jp(.+)$ {
proxy_pass http://jp.example.com$1;
}
location #rewrite {
rewrite ^/(.*)$ /index.php?q=$1;
}
location ~ '\.php$|^/update.php' {
fastcgi_split_path_info ^(.+?\.php)(|/.*)$;
include fastcgi_params;
fastcgi_param HTTP_PROXY "";
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
fastcgi_param PATH_INFO $fastcgi_path_info;
fastcgi_param QUERY_STRING $query_string;
fastcgi_intercept_errors on;
fastcgi_pass unix:/run/php/php7.0-fpm.sock;
}
}
I have left out some of the location entries, I think the above are the only relevant ones, especially the first one. This does result however, in a 404 on the example.com website since the /jp url is not a page.
When I visit jp.example.com directly it does work however. Can it be done and if so, how?

Answer 1

I think I found the solution:
location ~* ^/jp/ {
rewrite ^/jp/(.*)$ /$1 break;
proxy_pass http://jp.example.com:81/$1;
}
I added another vhost in a separate conf file listening to port 81. Though this does seem to work for a page, all files within the page (css, images etc) are still loading from example.com directly. So I think the domains module is still seeing it as the main website. Does nginx forward the original hostname somehow?
Update: I ended up with some nasty nginx tricks by rewriting URL's in the output HTML using the sub_filter module. It looks like this:
location ~ '\.php$|^/update.php' {
sub_filter 'href="/' 'href="http://www.example.com/jp/$1';
sub_filter 'src="/' 'src="http://www.example.com/jp/$1';
sub_filter 'jp.example.com' 'www.example.com/jp';
sub_filter_once off;
sub_filter_types *;
fastcgi_split_path_info ^(.+?\.php)(|/.*)$;
include fastcgi_params;
fastcgi_param HTTP_PROXY "";
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
fastcgi_param PATH_INFO $fastcgi_path_info;
fastcgi_param QUERY_STRING $query_string;
fastcgi_intercept_errors on;
fastcgi_pass unix:/run/php/php7.0-fpm.sock;
}
I had to hard code the URL's since $host points to jp.example.com. If you use multiple sub_filter declarations, they are not working on each other. So if you replace src="/test" with src="http://jp.example.com/test" and then replace "jp.example.com" for "www.example.com/jp" it doesn't get replaced. This means for every language I need to do this trick with hardcoded domains, but at least it works. I am not sure if this has any impact on the nginx performance though.