How-To Question: Need to write a proxy_pass statement but the upstream name is dynamically created in nginx-proxy docker version

[bplein]

How-To Question: Need to write a proxy_pass statement but the upstream name is dynamically created in nginx-proxy docker version.

Background: I need to integrate specific location stanzas for certain files and paths. I need to tell nginx-proxy something like this:

  location ~ ^/myresources/ {
    add_header Cache-Control "public, max-age=2419200, must-revalidate";
    add_header Strict-Transport-Security "max-age=63072000; includeSubDomains";
    try_files $uri @backend-via-proxy;
  }

  location @backend-via-proxy {
    proxy_pass http://my-backend;
    proxy_buffering on;
    proxy_redirect off;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection $connection_upgrade;

  }

The challenge is that with the containerized nginx-proxy, I have the upstream definitions created automatically. In my case, they look something like this:

# test.example.com/
upstream test.example.com-0123456789abcdef {
    # Container: test-example-com-web-1
    #     networks:
    #         nginx-proxy (reachable)
    #         test-example-com_internal_network (unreachable)
    #     IP address: 172.18.0.6
    #     exposed ports: 6000/tcp 8000/tcp
    #     default port: 80
    #     using port: 6000
    server 172.18.0.6:6000;
}

Since the alphanumeric portion of the upstream name is dynamically created, how do I create a proxy_pass line that references it?

[bplein]

By the way, the reason I have to pass to the backend is that these resources are inside the container, not mounted on a volume that could be attached to nginx-proxy. The issue is that the backend is dynamically named by nginx-proxy so I am unsure how to reference it.

[SchoNie]

The upstream name is not random. It is a sha1-hash of the VIRTUAL_PATH. So once you calculate it, you can re-use it.
In the Per-VIRTUAL_PATH location configuration there is a shell command to get the hash of the URL.
Or you could copy it from the generated config.

But normally nginx-proxy does the complex stuff for you.
See: Per-VIRTUAL_HOST location configuration and Per-VIRTUAL_PATH location configuration
If you create the _location file nginx-proxy will include it and you do not have to reference it.

[bplein]

Thanks. I didn't take the time to see if that was the same hash algorithm.... I have more than one upstream for this server, so I do need to know the name of the upstream and now that I know the generated value is stable and predictable, I can use it. Thanks, I'll try this today but I am sure this is the answer.