Traefik configuration inside docker-compose with subdomains - docker

Question

I try to setup subdomains configuration using traefik but is doesn't work. This is my docker-compose config :
traefik:
image: "traefik:v2.0.0-rc3"
container_name: "traefik"
command:
- "--api.insecure=true"
- "--providers.docker=true"
- "--providers.docker.exposedbydefault=false"
- "--entrypoints.web.address=:80"
ports:
- "80:80"
- "8282:8080"
volumes:
- "/var/run/docker.sock:/var/run/docker.sock:ro"
whoami:
image: "containous/whoami"
container_name: "simple-service"
labels:
- "traefik.enable=true"
#- "traefik.http.routers.whoami.rule=Host(`whoami.mydomain.com`)"
- "traefik.http.routers.whoami.entrypoints=web"
- "traefik.frontend.port=80"
- "traefik.frontend.rule=Host:whoami.mydomain.com"
When I replace the host by mydomain.com/whoami it does works correctly. I also tried to add the subdomain to /etc/hosts file but nothing changes when I go to whoami.mydomain.com nothing appears.
Do you have suggestions ?
Thanks.

Answer 1

I'm not an expert with Docker or Traefik, but I have been doing some work in that regard. The only thing I see that looks a bit weird to be is that you may want to throw a common network option on both to ensure they are sharing, such as:
networks:
- web
The only other guess would be if you are missing the DNS entry for whoami.yourdomain.com

Answer 2

For the record,
If append the following content to my /etc/hosts:
127.0.0.1 whoami.mydomain.com
the following snippet works on my machine:
version: '3'
services:
traefik:
image: "traefik:v2.5"
container_name: "traefik"
command:
- "--api.insecure=true"
- "--providers.docker=true"
- "--providers.docker.exposedbydefault=false"
- "--entrypoints.web.address=:80"
ports:
- "80:80"
- "8282:8080"
volumes:
- "/var/run/docker.sock:/var/run/docker.sock:ro"
whoami:
image: "containous/whoami"
container_name: "simple-service"
labels:
- "traefik.enable=true"
- "traefik.http.routers.whoami.rule=Host(`whoami.mydomain.com`)"
An yours with traefik:2.5 answers with a 404 not found on my machine.
Note: the port 8282 on my machine gives nothing (which is normal as nothing is listening in port 8080 in the container).