Nginx + regex, remove all parts of URI except the last one

1. In rewrite you match against URL's path part only. Which means, $1 will not contain the query string.
2. By default, Nginx appends original query string to the rewrite replacement.

So, it should be safe to write

rewrite ^(.*)$ $1?locale=de-de break;

In the case you do not want Nginx to append the original query string, simply specify ? in the end of replacement URL:

rewrite ^(.*)$ $1?locale=de-de? break;

So the user (eh... me) missed something that should have been a glaring clue:

In the above case I was able to load index.html when going to alarm.example.com (which correctly redirected to https://example.com/sub/alarm/), but all the resources were throwing a 404.

Even though that example still wasn't correct, I should have checked file permissions on the resource files. Nginx is running as www-data and in the group for the index.html file but needed to be in the group for all files. The file owner is the appusername user.

I've since added another app (called 'beer') which is routed like alarm. I've now learned the basics of regex and was able to do this in one location block:

server {
    listen 80;
    listen [::]:80 ipv6only=on;
    server_name example.com www.example.com;
    rewrite ^/(.*) https://example.com/$1 permanent;
}

server {
        listen 443 ssl;
        listen [::]:443 ipv6only=on ssl;
        charset utf-8;
        client_max_body_size 75M;
        server_name example.com www.example.com;
        ssl_certificate /etc/ssl/certs/example.com.crt;
        ssl_certificate_key /etc/ssl/private/example.com.key;
        error_log /var/log/nginx/error.log warn;

        location ~ ^/sub/(alarm|beer)(.*)$ {
                alias /home/appusername/$1.example.com/;
                #index  index.html index.htm;
                try_files $2 $2/ =404;
        }

        location / {
                include uwsgi_params;
                uwsgi_pass unix:///tmp/example.com.sock;
        }
}

server {
        listen 80;
        server_name alarm.example.com;
        rewrite ^ $scheme://example.com/sub/alarm$request_uri permanent;
}

Don't mind the switch in order for the location blocks. That is only coincidence of typing and retyping.