CODEWITHSUNDEEP
pythondockerdocker-composemqtt
alanionita
alanionita

Reputation: 1443

Connection refused when connecting from one docker container to another [same network]

Having a hard time debugging this. I have one container starting an MQTT server and another Python container trying to connect.

Using docker-compose to orchestrate and have set up a network and connected both containers to it.

Currently I can connect to the MQTT server independently with docker run and with docker-compose, but the Python containe for some reason cannot connect.

I'm thinking it may be a firewall issue?

In the main.py I'm printing the MQTT_HOST and MQTT_PORT and I can actually connect to those using a local Mosquitto client.

docker-compose.yml

version: "3.3"
services:
  webserver:
    build: ./webservice/server
    ports:
      - 3001:3001
      - 3002:3002
    networks:
      - project-network
    command: npm run start
  inferemce:
    build: ./inference
    ports:
      - 3003:3003
    networks:
      - project-network
    depends_on:
      - webserver
    restart: on-failure
    command: ["./wait-for-it.sh", "webserver:3001", "--", "python", "main.py"]

networks:
  project-network:
    driver: bridge

main.py

import socket
import paho.mqtt.client as mqtt

HOSTNAME = socket.gethostname()
IPADDRESS = socket.gethostbyname('localhost')
MQTT_HOST = IPADDRESS
MQTT_PORT = 3001
MQTT_KEEPALIVE_INTERVAL = 60

def connect_mqtt():
    print('host', MQTT_HOST)
    print('port', MQTT_PORT)
    client = mqtt.Client()
    client.connect(MQTT_HOST, MQTT_PORT, MQTT_KEEPALIVE_INTERVAL)
    return client

def main():
    client = connect_mqtt()



if __name__ == '__main__':
    main()

Upvotes: 0

Views: 1914

Answers (1)

hardillb
hardillb

Reputation: 59618

You are trying to connect to localhost which is going to be the container the python app is running in, not webserver.

Change the python to try to look up the address of webserver rather than localhost

import socket
import paho.mqtt.client as mqtt

HOSTNAME = socket.gethostname()
IPADDRESS = socket.gethostbyname('webserver')
MQTT_HOST = IPADDRESS
MQTT_PORT = 3001
MQTT_KEEPALIVE_INTERVAL = 60
...

Upvotes: 1

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