HAProxy boshrelease + Docker boshrelease linking

I'm using the HAProxy boshrelease and the Docker boshrelease in the bosh release. I'm trying to link them, but nothing I tried yet worked. In the HAProxy config section, I'm using the tcp_link_port, but this does not work, obviously. Does anyone have successfully linked these two boshreleases or knows how to configure it?

Here is my manifest:

instance_groups:
- azs:
  - az2
  instances: 1
  jobs:
  - name: haproxy
    properties:
      ha_proxy:
        backend_port: 80
        tcp_link_port: 4447
    release: haproxy
  name: haproxy
  networks:
  - [...]
- azs:
  - z2
  instances: 3
  jobs:
  - name: docker
    properties:
      insecure_registries:
      - ((insecure-registry))
      [...]
    release: docker
  - depends_on:
    - docker
    name: containers
    properties:
      containers:
      - bind_ports:
        - 80:8080
        - 4447:4447
        name: mydocker
     [...]
    release: docker

Best regards

Onke

I was able to "solve" this issue by manually targeting the backend servers:

tcp:  
- backend_port: 4447
  backend_servers: "((backend-ips.key_list))"
  name: awesomeBackend
  port: 4447

Where backend-ips is a CredHub entry of the type json.