Ping reverse proxy from container via DNS

Docker Engine Compose
1

Hi,
I am using traefik as a reverse proxy that routes HTTP requests to the according container by matching the request domain.
Let’s say I have the following containers:

  • traefikContainer
  • apiContainer (as htp://api.local:80 via traefik)
  • frontendContainer (as htp://frontend.local:80 via traefik)

I can access both containers via the reverse proxy from my host machine.

Now i want to send HTTP requests from frontendContainer to htp://api.local.
This used to work a year ago with:

# frontendContainer/docker-compose.yml
services:
  frontendContainer:
    networks:
      traefik_default:
        aliases:
          - api.local

But now docker exec frontendContainer ping api.local returns 127.0.0.1 instead of traefiks IP address.

All I want, is to send an HTTP request from frontendContainer to apiContainer via traefikContainer by addressing htp://api.local.
How can this be achieved?

(must use htp instead of http to circumvent post restrictions)

UPDATE
I found a workaround:

services:
  frontendContainer:
    extra_hosts:
      - "api.local:host-gateway"

This way, the request will be routed to the host system, from which the reverse proxy is reachable.

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