Document complete reverse proxy for individual container setup

[mStirner]

map $http_upgrade $connection_upgrade {
  default upgrade;
  ''      close;
}

server {

    listen 80 default_server;
    server_name 127.0.0.1 localhost ${NGINX_HOSTNAME};

    # remove server version
    server_tokens off;

    root /usr/share/nginx/html;

    autoindex off;  
    access_log off;  

    location = /favicon.ico { access_log off; log_not_found off; }
    location = /robots.txt  { access_log off; log_not_found off; }

    location ~ /(api|auth)/(.*)$ {
        resolver ${RESOLVER};
        proxy_pass ${BACKEND_PROTOCOL}://${BACKEND_HOST}:${BACKEND_PORT}/$1/$2;
        proxy_http_version 1.1;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header Connection $connection_upgrade;
        proxy_set_header Upgrade $http_upgrade;
        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 /admin {
        resolver ${RESOLVER};
        proxy_pass ${ADMIN_PROTOCOL}://${ADMIN_HOST}:${ADMIN_PORT};
        proxy_http_version 1.1;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header Connection $connection_upgrade;
        proxy_set_header Upgrade $http_upgrade;
        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 / {
        resolver ${RESOLVER};
        proxy_pass ${FRONTEND_PROTOCOL}://${FRONTEND_HOST}:${FRONTEND_PORT};
        proxy_http_version 1.1;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header Connection $connection_upgrade;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }

}