So I have a webserver running nginx, and I want to use it as a reverse proxy to access web applications running elsewhere. I know this is a pretty standard use case, and that the traditional approach is to use virtual hosts to proxy the different apps.

Like, normally you would do something like:

• https://app1.webserver.something => app1.host:3000
• https://app2.webserver.something => app2.host:1234
• https://app3.webserver.something => app3.host:8080

I am familiar with this approach, and know how to set it up.

In this case, there is a catch though. For reasons that I can’t get into here, I can’t use virtual hosts, and everything should be hosted in the same webserver.something domain. So I thought I would use a subpath to host each app.

What I want to do is this basically:

• https://webserver.something/app1 => app1.host:3000
• https://webserver.something/app2 => app2.host:1234
• https://webserver.something/app3 => app3.host:8080

In my nginx config file I have something like this:

upstream app1 {
  server app1.host:3000;
}

server {
    ...
    location /app1 {
        proxy_pass http://app1/;
    }
    ...
}

This works to the extent that all requests going to /app1/* get forwarded to the correct application host. The issue though is that the application itself uses absolute paths to reference some resources. For example, app1 will try to reference a resource like /_app/something/something.js, which of course produces a 404 error.

I suppose that for this particular error I could map /_app/ to the app1 application host with another location statement, but that seems dirty to me and I don’t like it. First off it could quickly become a game of whack-a-mole, trying to get all the absolute paths remapped, and secondly it could easily lead to conflicts if other applications use that absolute path too.

So I guess my question is: is there a way to do this cleanly, and dynamically rewrite those absolute paths per app?