Forwardauth to Authelia for dynamic file

Trying to set forwardauth authentication to Authelia for dynamic file configuration but I'm not able to go get it working. Authelia is running as a docker container and it works as intended for containers using this label:

      #Authelia authentication
      - "traefik.http.routers.myapp-secure.middlewares=authelia@docker"

However, attempting to do similar with the my dynamic file it simply gets ignored:

http:
  routers:
    myotherapp:
      entryPoints:
        - "http"
      rule: "Host(`myotherapp.domain.tld`)"

      middlewares:
        - "myotherapp-https-redirect"
        - "authelia@docker"
      service: myotherapp

    myotherapp-secure:
      entryPoints:
        - "https"
      rule: "Host(`myotherapp.domain.tld`)"
      tls:
        certResolver: le
      service: myotherapp


  services:
    myotherapp:
      loadBalancer:
        servers:
          - url: "https://192.xxx.xxx.xxx"
        passHostHeader: true


  middlewares:
    myotherapp-https-redirect:
      redirectScheme:
        scheme: https

Thanks

Where is the authelia middleware defined? You only assign it. Check docs.