No route to host from inside docker container

Traefik Traefik v2
1

I am using Traefik with docker compose.

I am able to reach my docker containers just fine at their traefik hosts. I am even able to ping the hosts from the command line of the containers themselves. However, inside the docker containers, I cannot reach the hosts using python requests or urllib3. It errors out with errno: 113, no route to host.

So for example, I can reach and browse to http://sentry.mydomain from any web browser, so I know that part of traefik and my containers are working.

I can ping sentry.mydomain from from the command line INSIDE any docker container. eg

# docker-compose run web bash
# ping sentry.mydomain
64 bytes from ... (success)

However, from python, INSIDE any docker container I cannot reach sentry.mydomain. even though I was just able to ping it. eg

# docker-compose run web bash
# ping sentry.mydomain
64 bytes from ... (success)
# python
>>> import requests
>>> r = requests.get('http://sentry.mydomain')
# stack trace ... Failed to establish a new connection: [Errno 113] No route to host'))

Examples from docker-compose.yml:

  sentry_web:
    <<: *defaults
    ports:
      - "9000:9000"
    expose:
      - 9000
    networks:
      - web
      - internal
    labels:
      - "traefik.enable=true"
      - "traefik.backend=sentry"
      - "traefik.http.routers.sentry.rule=Host(`sentry.mydomain`)"
      - "traefik.http.routers.sentry.entrypoints=web"
      - "traefik.docker.network=web"
      - "traefik.port=9000"
traefik:
    image: "traefik:v2.0.0-rc3"
    container_name: "traefik"
    command:
      - "--log.level=DEBUG"
      - "--api.insecure=true"
      - "--accesslog"
      - "--providers.docker=true"
      - "--providers.docker.exposedbydefault=false"
      - "--entrypoints.web.address=:80"
    ports:
      - "80:80"
      - "8080:8080"
    networks:
      - web
    volumes:
      - "/var/run/docker.sock:/var/run/docker.sock:ro"
2

Hi @j-gooding, can you try with latest traefik stable version first? you are using a release candidate, which is not really fresh :slight_smile: Try with latest stable, traefik:2.0.5.

Also, as it looks closely related to the docker network, could you provide a full reporoduction case? The compose file you provided is not complete (no network definition, the "parent" block default is not there, etc.) so we cannot really help you here.

3

Did you find a solution to this problem? I have the same problem right now.

4

It seems to be related to firewall/iptables issue but i didn't catch the solution yet.
Any advice ?

In my case, 2 container are connect to another traefik container.
From 1 container, i try to access to the other by the VIP traefik interface (the same IP, redirect by DNS).

image

5

any idea guys ?
Thanks by advance.

6

Up !
Appreciate by advance any clue.