503 with podman socket

Trying to get this running with the podman socket with the following setup:

  docker-socket-proxy:
    image: tecnativa/docker-socket-proxy
    container_name: docker-socket-proxy
    restart: always
    privileged: true
    environment:
      - SOCKET_PATH=/run/podman/podman.sock
      - CONTAINERS=1
    security_opt:
      - label=disable
    volumes:
      - /run/podman/podman.sock:/run/podman/podman.sock:ro

Seem to be getting a 503 though, not sure why.

HAProxy logs:

10.69.0.155:37856 [27/Feb/2022:07:55:28.777] dockerfrontend dockerbackend/dockersocket 0/0/-1/-1/0 503 213 - - SC-- 1/1/0/0/3 0/0 "GET /containers/baba2851b7771b0603152904c27ac5a354850a10a8414e06fcfa616754e5610b/json HTTP/1.1"
10.69.0.155:37858 [27/Feb/2022:07:55:28.895] dockerfrontend dockerbackend/dockersocket 0/0/-1/-1/0 503 213 - - SC-- 1/1/0/0/3 0/0 "GET /containers/2ef63ee42473922c7e999dd380e81058a212c8e8b67871f61f7645f60958d891/json HTTP/1.1"
10.69.0.155:37862 [27/Feb/2022:07:55:29.013] dockerfrontend dockerbackend/dockersocket 0/0/-1/-1/0 503 213 - - SC-- 1/1/0/0/3 0/0 "GET /containers/2ef63ee42473922c7e999dd380e81058a212c8e8b67871f61f7645f60958d891/json HTTP/1.1"

If I exec into the container and try to access the socket though, it works fine:

/ # curl --unix-socket /var/run/podman/podman.sock docker-socket-proxy:3725/containers/faade8bf2b744d7799623d27ff550da8e257e1aa0142d0b6ab5379481ae07aff/json

{"Id":"faade8bf2b744d7799623d27ff550da8e257e1aa0142d0b6ab5379481ae07aff","Created":"2022-02-20T20:38:48.884569982Z",..........................

Start with the docker-socket-proxy compose configuration and the HAProxy 503 log entries, then compare them with the successful curl request made from inside the container. Determine why the HAProxy requests fail while direct socket access succeeds; done means identifying a reproducible cause and a documented configuration change.