Forward requests to a new service based on url

Traefik Traefik v2
,
1

I'm working on transferring our current setup from haproxy to træfik.
We have a versioned api, which is url versioned like this:

host/1/api
host/2/api
host/3/api

etc.

In addition you can access our latest api at host/api. Our api versions run in different docker containers, and translating the old haproxy config into labels in docker has been a breeze (host and prefix matching), however there is one thing I can't seem to figure out:
How can I make host/api always redirect to the latest version? I can do something when we deploy a new container, but I would prefer to not having to touch old containers every time we do a new deploy.

I was hoping I could use a dynamic file config for this, but so far I haven't really figured out how.
Basically I want host/api to rewrite to host/3/api which should then hit correct service for host/3/api.
When we deploy version 4 of our api (host/4/api), I would like to make host/api now rewrite to /host/4/api and hit that service.

The closests I think I got was using a weighted loadBalancer, but still no dice.
I have whoami1-3 running in docker and able to respond on /[1-2]/api right now.
The general idea is a that I could just replace prefix = "2" and name = "whoami2-traefik@docker" with whatever comes at next deploy (3 in this case)

[http.routers]
  [http.routers.whoami]
      rule = "Host(`whoami.docker.localhost`) && PathPrefix(`/api/`)"
      middlewares = ["add-api-prefix"]
      entryPoints = ["https"]
      service = "whoami"

[http.services]
  [http.services.whoami]
    [[http.services.whoami.weighted.services]]
      name = "whoami2-traefik@docker"

[http.middlewares]
  [http.middlewares.add-api-prefix.addPrefix]
    prefix = "2"

Grateful for any help!

2

Seems like I got it working adding tls. I'll leave it here in case anyone else needs something similar.

[http.routers]
  [http.routers.whoami]
      rule = "Host(`whoami.docker.localhost`) && PathPrefix(`/api/`)"
      middlewares = ["add-api-prefix"]
      entryPoints = ["https"]
      service = "whoami"
  [http.routers.whoami.tls]

[http.services]
  [http.services.whoami]
    [[http.services.whoami.weighted.services]]
      name = "whoami2-traefik@docker"

[http.middlewares]
  [http.middlewares.add-api-prefix.addPrefix]
    prefix = "2"