grafana compose on Docker swarm mode

# Traefik started with
#   docker service create --constraint=node.role==manager --publish 80:80 --publish 443:443 --mount type=bind,source=/var/run/docker.sock,target=/var/run/docker.sock --network traefik-internal traefik --docker --docker.swarmmode --docker.domain=traefik --docker.watch --web
# running this with docker stack deploy --compose-file docker-compose-swarm.yml  grafana

  version: '3'
  services:
    grafana:
      image: grafana/grafana:4.1.2
      ports:
        - "8085:3000"
      networks:
        - traefik
      deploy:
        labels:
          - "traefik.frontend.rule=Host:grafana.test.net"
          - "traefik.docker.network=traefik-internal"
          - "traefik.port=8085"
        placement:
          constraints:
            - node.role == manager
      environment:
        - GF_SERVER_ROOT_URL=https://grafana.test.net
  networks:
    traefik:
      external:
        name: "traefik-internal"