Gitlab runner clone timeout behind traefik (relative path)

Question

I am trying to get a instance of Gitlab running on a relative path (/dev/git/) behind a Traefik proxy.
Gitlab itself works like a charm, but I have no luck with adding a Runner to the project.

The registration of the runner ist successfully, but when it grabs a job, the cloning of the repository fails with a timeout error:

Cloning into '/builds/dev/git/root/ci-test'...
fatal: unable to access 'https://gitlab-ci- 
token:xxxxxxxxxxxxxxxxxxxx@SUBDOMAIN.DOMAIN.de/dev/git/root/ci-test.git/': Failed to connect to SUBDOMAIN.DOMAIN.de port 443: Operation timed out

Gitlab is available under https://SUBDOMAIN.DOMAIN.de/dev/git/

Docker-Config "docker-compose.yml":

version: "2.1"
services:
  proxy1:
    container_name: proxy1
    image: traefik:latest
    restart: always
    networks:
      - web
    ports:
      - 80:80
      - 443:443
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - /srv/docker/config/proxy1/acme.json:/acme.json
      - /srv/docker/config/proxy1/traefik.toml:/traefik.toml
    labels:
      - "traefik.docker.network=web"
      - "traefik.enable=true"
      - "traefik.basic.frontend.rule=Host:SUBDOMAIN.DOMAIN.de;PathPrefixStrip:/traefik/"
      - "traefik.basic.port=8080"
      - "traefik.basic.protocol=http"
  gitlab1:
    container_name: gitlab1
    image: gitlab/gitlab-ce:latest
    restart: always
    networks:
      - web
    volumes:
      - /srv/docker/volumes/gitlab1/config:/etc/gitlab
      - /srv/docker/volumes/gitlab1/log:/var/log/gitlab
      - /srv/docker/volumes/gitlab1/data:/var/opt/gitlab
    labels:
      - "traefik.docker.network=web"
      - "traefik.enable=true"
      - "traefik.basic.frontend.rule=Host:SUBDOMAIN.DOMAIN.de;PathPrefix:/dev/git/"
      - "traefik.basic.port=80"
      - "traefik.basic.protocol=http"
  gitlab-runner1:
    container_name: gitlab-runner1
    image: gitlab/gitlab-runner:latest
    restart: always
    networks:
      - web
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - /srv/docker/volumes/runner1/config:/etc/gitlab-runner
networks:
  web:

Traefik config "traefik.toml":

debug = true

logLevel = "ERROR"
defaultEntryPoints = ["https", "http"]

[entryPoints]
  [entryPoints.http]
  address = ":80"
    [entryPoints.http.redirect]
    entryPoint = "https"
  [entryPoints.https]
  address = ":443"
  [entryPoints.https.tls]

[retry]

[docker]
endpoint = "unix:///var/run/docker.sock"
domain = "SUBDOMAIN.DOMAIN.de"
watch = true
exposedByDefault = false

[acme]
email = "MAIL@EXAMPLE.de"
storage = "acme.json"
entryPoint = "https"
onHostRule = true
[acme.httpChallenge]
entryPoint = "http"

[api]
entryPoint = "traefik"
dashboard = true

Gitlab is configured to listen on HTTP behind the proxy, which handles SSL.
Gitlab config "gitlab.rb":

external_url "https://SUBDOMAIN.DOMAIN.de/dev/git/"
nginx['redirect_http_to_https'] = true
nginx['listen_port'] = 80 
nginx['listen_https'] = false
nginx['proxy_set_headers'] = {
 "Host" => "$http_host",
 "X-Real-IP" => "$remote_addr",
 "X-Forwarded-For" => "$proxy_add_x_forwarded_for",
 "X-Forwarded-Proto" => "https",
 "X-Forwarded-Ssl" => "on"
}

Gitlab-Runner config "config.toml":

concurrent = 1
check_interval = 0

[session_server]
  session_timeout = 1800

[[runners]]
  name = "runner1"
  url = "http://gitlab1/dev/git/"
  token = "TOKEN"
  executor = "docker"
  [runners.docker]
    tls_verify = false
    image = "alpine:latest"
    privileged = false
    disable_entrypoint_overwrite = false
    oom_kill_disable = false
    disable_cache = false
    volumes = ["/cache"]
    shm_size = 0
  [runners.cache]
    [runners.cache.s3]
    [runners.cache.gcs]

It would be a pleasure for me, if you could help me with this. I searched a lot on the internet, but I can't find anyone who already solved this.
Thank you very much for every answer.

Answer 1

I figured out a solution:

The job, which is running on the gitlab-runner, doesn't connect to the web network, but to the standard bridge network.

So I had to reconfigure the gitlab runner as followed by adding:

[[runners]]
url = "http://gitlab1/dev/git/"
clone_url = "http://gitlab1/dev/git/"
[runners.docker]
    network_mode = "docker_gitlab"
    privileged = true

docker_gitlab is the name of the network, which I added to the docker-compose file above to connect gitlab and the gitlab-runner.

new docker-compose.yml

gitlab1:
  container_name: gitlab1
  image: gitlab/gitlab-ce:latest
  restart: always
  networks:
    - gitlab
    - web
  volumes:
    - /srv/docker/volumes/gitlab1/config:/etc/gitlab
    - /srv/docker/volumes/gitlab1/log:/var/log/gitlab
    - /srv/docker/volumes/gitlab1/data:/var/opt/gitlab
  hostname: SUBDOMAIN.DOMAIN.de
  labels:
    - "traefik.enable=true"
    - "traefik.docker.network=docker_web"
    - "traefik.port=80"
    - "traefik.backend=gitlab"
    - "traefik.frontend.rule=Host:SUBDOMAIN.DOMAIN.de;PathPrefix:/dev/git/"
gitlab-runner1:
  container_name: gitlab-runner1
  image: gitlab/gitlab-runner:latest
  restart: always
  networks:
    - gitlab
  volumes:
    - /var/run/docker.sock:/var/run/docker.sock
    - /srv/docker/volumes/runner1/config:/etc/gitlab-runner
  links:
    - gitlab1
  labels:
    - "traefik.enable=false"