Docker: Unable to ping another host from inside of container running in swarm

[yogeshkathayat]

Environment:-

• Ubuntu 18.04
• Docker version 18.09.7, build 2d0083d
• image yogeshkathayat/node-ping which is a simple nodejs app running on a node-alpine build
• my current host IP: 10.255.8.21
• Ip that I want to ping: 10.255.8.53

My compose file:-

version: "3.3"
networks:
  basic:
services:
  ping-test:
    image: yogeshkathayat/node-ping
    deploy:
      replicas: 1
    networks:
      - basic
    ports:
      - "3000:3000"

Issue:- I am not able to ping another host in the same local network from inside of the container, if I remove ports section from my Compose file then it is working perfectly. but I want to expose the port to the outside world.

Steps:-

1. docker swarm init
2. docker stack deploy --compose-file docker-compose.yml ping
3. docker exec -it /bin/bash //go inside the container
4. ping host in the same subnet or network

[information-security]

Please use this format for your ports and see if it solves your problem:

ports:
  - target: 3000
    published: 3000
    protocol: tcp
    mode: host

[Ga11u]

Did you tried to use tasks. as address ? https://docs.docker.com/network/overlay/#container-discovery

[justincormack]

This issue is for https://github.com/docker/swarmkit not the old standalone Swarm.