Communication between Docker containers on differents hosts in the same local network

Question

I have two Docker containers running on two different hosts:

• Computer A (PC, uses Ethernet), ip 192.168.0.11 [ Docker container running inside on 172.17.0.2 ], OS Windows 7
• Computer B (laptop, uses WLAN), ip 192.168.0.12 [ Docker container running inside on 172.17.0.2 ], OS Linux Ubuntu

I would like to somehow connect them, so they could communicate with each other (e.g. via ssh).

I have tried to "link" my containers by running them with:

docker run --name master_node --rm -it branislava/ubuntu1504java8:v1

docker run --rm -it --link master_node:master_node1 --name slave_node branislava/ubuntu1504java8:v1

As suggested in comments. This is working; containers can communicate - but only when they are run on the same host machine.

How could this be accomplished for containers that are running on different machines in the same local network?

Answer 1

Following is the bash script for establishing communication between docker containers of the same image across different hosts in the same local network:

 # Firstly, we have to make a swarm
 # We have to discover ip address of the swarm leader (i.e. manager, master node)
 ifconfig
 # My master computer has ip 192.168.0.12 in the local network
 sudo docker swarm init --advertise-addr 192.168.0.12
 # Info about swarm
 sudo docker info
 # info about nodes (currently only one)
 sudo docker node ls
 # hostaname got it name automatically, by the host's name

 # adding new nodes to the swarm
 # ssh to the slave node (i.e. worker node) or type physically:
 # this command was generated after 
 # sudo docker swarm init --advertise-addr 192.168.0.12
 # on manager computer
 docker swarm join --token SWMTKN-1-55b12pdctfnvr1wd4idsuzwx34vcjwv9589azdgi0srgr3626q-01zjw639dyoy1ccgpiwcouqlk  192.168.0.12:2377

 # if one cannot remember or find this command
 # should type again on the manager host
 docker swarm join-token worker

 # ssh to the manager or type in directly:
 # (listing existing nodes in a swarm)
 sudo docker node ls
 # adding docker image as a process that will run in this containers
 # ssh to the manager or type in directly:
 # replicas will be the number of nodes
 # manager is also a worker node
 sudo docker service create --replicas 2 --name master_node image-name sleep infinity
 # I have to enter inside of the containers and set up some things before
 # running application, so I say `sleep infinity`
 # Else, this is not necessary.

 # what's up with the running process
 sudo docker service inspect --pretty etdo0z8o8timbsdmn3qdv381i
 # or
 sudo docker service inspect master_node
 # also, but only from manager
 sudo docker service ps master_node
 # see running containers (from worker or from manager)
 sudo docker ps

#  promote node from worker to manager
# `default` is the name of my worker node
sudo docker node promote default
#  denote node from manager to worker
sudo docker node demote default

# entering container, if needed
# getting container id with `sudo docker ps`
sudo docker exec -it bb923e379cbd  bash

# retrieving ip and port of the container
# I need this since my containers are communicating via ssh
sudo docker ps
sudo docker inspect --format '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' 5395cdd22c44

# removing processes from all nodes
sudo docker service rm master_node
# this command should say `no process`
sudo docker service inspect master_node

Hopefully, someone will find this helpful.

Answer 2

show us the docker command.

i think in your command is missing the link

here is an example

docker run --name=redmine -it --rm --link=postgresql-redmine:postgresql \
  --volume=/srv/docker/redmine/redmine:/home/redmine/data \
  sameersbn/redmine:3.3.1

Answer 3

i have never try it but so you can to accomplish a other pc

docker run --name=Client -it --rm \
      --env='MEMCACHE_HOST=192.168.1.12' --env='MEMCACHE_PORT=22' \

Answer 4

I know this is old post.If ssh on containers is set up and port 22 is opened,you need to find out mapped port for external connections.This is not a solution but you can try out

Run this command on laptop B

  docker port master_node1 22

if the port is open it will give you some port number other wise errors out,eg if output of above command is

          0.0.0.0:1234

ssh from laptop A to container on laptop B

      ssh [email protected] -p 1234