cannot run node-red-docker behind nginx docker with virtual directory.

What are the steps to reproduce?

install:

1. ubuntu 20.04 desktop
2. docker-ce 19.03.12
3. node-red 1.0.6 (from latest docker)
4. nginx docker
5. launch a virtual directory named "form" and set proxy_pass to node-red container in nginx conf file.

What happens?

proxy_pass may work, but some static reference library cannot be located correctly.

I had tried to modify httpAdminRoot, httpNodeRoot, httpRoot, httpStatic in settings.js, seems not the correct setting item for this case.

nginx setting

upstream form {
  server form:1880;  <-- node-red container
}

server {
...
  location ~ ^/form(/?)(.*) {
    proxy_pass http://form/$2;
    proxy_http_version 1.1;
    proxy_set_header Host $http_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 $scheme;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
  }

  location / {
    ...  <- run other pages here.
  }
}

Beginne damit, das Setup mit den angegebenen Versionen von Ubuntu, Docker, Node-RED und nginx zu reproduzieren. Untersuche anschließend die nginx-Serverkonfiguration und die genannten Optionen in settings.js. Das Problem ist behoben, wenn die Node-RED-Oberfläche und ihre statischen Referenzen korrekt über das virtuelle Verzeichnis /form geladen werden.