ZeroMQ does not support communication between two Docker containers

Question

I am trying to create a toy example of a Docker network with ZeroMQ on macOS where it serverd.pysends a message to clientd.pyand the client simply displays it using PUSH / PULL. If I run them outside the container, they work fine, but I have problems with their connection when working in separate containers. It seems that mine clientd.pycannot connect to the name of the container, despite the fact that it is on the same bridge network. I tried replacing the hostname with the assigned IP address for serverd_dev_1, but that will not work either.

Here is my setup:

• I created a new network with docker network create -d bridge mynet. Here is the result from docker network inpsect mynet:

  {
      "Name": "mynet",
      "Id": "cec7f8037c0ef173d9a9a66065bb46cb6a631fea1c0636876ccfe5a792f92412",
      "Created": "2017-08-19T09:52:44.8034344Z",
      "Scope": "local",
      "Driver": "bridge",
      "EnableIPv6": false,
      "IPAM": {
          "Driver": "default",
          "Options": {},
          "Config": [
              {
                  "Subnet": "172.18.0.0/16",
                  "Gateway": "172.18.0.1"
              }
          ]
      },
      "Internal": false,
      "Attachable": false,
      "Ingress": false,
      "ConfigFrom": {
          "Network": ""
      },
      "ConfigOnly": false,
      "Containers": {
          "5fa8dc2f8059d675dfd3dc4f2e50265be99361cd8a8f2730eb273772c0148742": {
              "Name": "serverd_dev_1",
              "EndpointID": "3a62e82b1b34d5c08f2a9f340ff93aebd65c0f3dfde70e354819befe21422d0b",
              "MacAddress": "02:42:ac:12:00:02",
              "IPv4Address": "172.18.0.2/16",
              "IPv6Address": ""
          },
          "ec1e5f8c525ca8297611e02bcd3a64198fda3a07ce8ed82c0c4298609ba0357f": {
              "Name": "clientd_dev_1",
              "EndpointID": "a8ce6f178a225cb2d39ac0009e16c39abdd2dae02a65ba5fd073b7900f059bb8",
              "MacAddress": "02:42:ac:12:00:03",
              "IPv4Address": "172.18.0.3/16",
              "IPv6Address": ""
          }
      },
      "Options": {},
      "Labels": {}
  }
  

• serverd.py clientd.py Dockerfiles docker-compose.yml:

serverd.py:

import zmq
import time

context = zmq.Context()
socket = context.socket(zmq.PUSH)
address = "tcp://127.0.0.1:5557"
socket.bind(address)
print("Sending to {}...".format(address))
while True:
    message = socket.send_string("Got it!")
    print("Sent message")
    time.sleep(1)

clientd.py:

import zmq

context = zmq.Context()
socket = context.socket(zmq.PULL)
address = "tcp://serverd_dev_1:5557"
socket.connect(address)
print("Listening to {}...".format(address))
while True:
    message = socket.recv_string()
    print("Client got message! {}".format(message))

Dockerfiles docker-compose.yml:

serverd.py:

FROM python:3.6

RUN mkdir src
ADD serverd.py /src/
RUN pip install pyzmq
WORKDIR /src/
EXPOSE 5557

Dockerfile clientd.py:

FROM python:3.6

RUN mkdir src
ADD clientd.py /src/
RUN pip install pyzmq
WORKDIR /src/
EXPOSE 5557

docker-compose.yml serverd.py:

dev:
  build: .
  command: ["python", "-u", "./serverd.py"]
  net: mynet

docker-compose clientd.py:

dev:
  build: .
  command: ["python", "-u", "./clientd.py"]
  net: mynet

3. serverd.py , , docker-compose up:

Sending to tcp://127.0.0.1:5557...

4. clientd.py , tcp://serverd_dev_1:5557.

   Attaching to countd_dev_1
   dev_1  | Traceback (most recent call last):
   dev_1  |   File "./countd.py", line 6, in <module>
   dev_1  |     socket.connect(address)
   dev_1  |   File "zmq/backend/cython/socket.pyx", line 528, in zmq.backend.cython.socket.Socket.connect (zmq/backend/cython/socket.c:5971)
   dev_1  |   File "zmq/backend/cython/checkrc.pxd", line 25, in zmq.backend.cython.checkrc._check_rc (zmq/backend/cython/socket.c:10014)
   dev_1  | zmq.error.ZMQError: Invalid argument
   

5. URI tcp://serverd_dev_1:5557 tcp://172.18.0.2:5557, , - . , - , , . , , , - .

Answer 1

, tcp://127.0.0.1:5557. localhost (127.0.0.1), . , , . :

address = "tcp://0.0.0.0:5557"

, serverd_dev_1 , , serverd ( , docker-compose up. ]).

docker-compose.yaml. , :

version: "2"

services:
  serverd:
    build: serverd
    command: ["python", "-u", "./serverd.py"]
    environment:
      SERVER_LISTEN_URI: tcp://0.0.0.0:5557

  clientd:
    build: clientd
    command: ["python", "-u", "./clientd.py"]
    environment:
      SERVER_CONNECT_URI: tcp://serverd:5557

( , docker-compose ), mynet.

, , , , URI ZMQ , . docker-compose.yaml :

• https://github.com/larsks/so-example-jimmyc

/ docker-compose.yaml, , . alias , , :

version: "2"

services:
  serverd:
    build: .
    command: ["python", "-u", "./serverd.py"]
    environment:
      SERVER_LISTEN_URI: tcp://0.0.0.0:5557
    networks:
      mynet:
        aliases:
          - serverd

networks:
  mynet:
    external: True

, mynet .