Reverse proxy for Angular app (with all the resources js|css|ico|txt|jpg|svg..)

Hello everyone.

I am facing problem where cannot succeed with the proper reverse proxy configuration for the App having needing resources (js|css|ico|txt|jpg|svg) to load as well so it can work.

Scenario is that I have a Spring Boot App with Angular on the frontend. I have built a Docker image of this app.

How it looks locally:

opening in browser:
http://192.168.255.11:59901/spring/webapp (no trailing slash)
will redirect to:
http://192.168.255.11:59901/spring/webapp/login?returnUrl=%2F
giving you the app (with all resources like js|css|owa|etc.. loaded):

How I want to to look like publicly:

a) alias_for_client.example.com (addPrefix: /spring/webapp) - access only to angular context
b) alias_for_admin.example.com/webapp (addPrefix: /spring) - access to admin tools of spring boot (/spring/swagger, /spring/explorer, /spring/h2-database, /spring/acucator, etc.

Simply put I want to have http://192.168.255.11:59901 put under subdomain and strip the path segment (or add it in the background) as described above.

Config example for scenario a) (access only to angular context at /spring/webapp)

http:

  routers:
    alias1.example.com:
      entryPoints:
        - websecure
      rule: Host(`alias1.example.com`)
      service: alias1.example.com

  services:
    alias1.example.com:
      loadBalancer:
        passHostHeader: true
        servers:
          - url: 'http://192.168.255.11:59901'
      middlewares:
        - alias1.example.com+addPrefix

  middlewares:
    alias1.example.com+addPrefix:
      addPrefix:
        prefix: /spring/webapp
    alias1.example.com+replacePathRegex:
      replacePathRegex:
        regex: "^/spring/webapp"
        replacement: "/"
    alias1.example.com+redirectRegex:
      redirectRegex:
        regex: "^https?://([^/]+)/?$"
        replacement: "https://$1/spring/webapp"
        permanent: true

-- don't mind those other 2 middlewares - I was experimenting.. active is only the first one.

If somebody can point me what I might be doing wrong please. Thanks!