Docker-Compose使用python连接到远程MQTT代理

Question

Totally new to Docker-Compose and I kind of breaking my face repeatedly. I try to connect to an existing mqtt broker (my broker on another pc) over docker-compose, with a test python script that is working standalone.

This is the Python testscript. I also tried to print in Terminal but with no luck. So help is appreciated on this one too.

import json
import base64
import binascii
import time
import datetime
from collections import defaultdict
import paho.mqtt.client as mqtt
import paho.mqtt.publish as publish
import ssl

def on_message(mosq, obj, msg):
    print(msg.topic + " " + str(msg.qos) + " " + str(msg.payload))

def on_connect(client, userdata, a, b):
    print("Connected to Broker")




def on_disconnect(client, userdata, rc):
    print("Disconnected from MQTT server with code: ", rc)


mqttc = mqtt.Client(client_id="RELAY", clean_session=False)
mqttc.on_message = on_message
mqttc.on_connect = on_connect
mqttc.on_disconnect = on_disconnect
mqttc.connect("1.1.1.2", 1883, 60)

mqttc.loop_start()

counter = 0 
while True:
    print("Sending MSG")
    counter=counter+1
    response="MESSAGE No: "+ str(counter) 
    mqttc.publish("Walrus/test", response)

    time.sleep(30)

This is one of the thousands instances of the yml file I tried.

version: '3'
services:
  mqtt:
     broker: 1.1.1.2
     port:1883

This instance just returns that broker is unsupported config option

This is the Dockerfile

FROM python:3.6.1-alpine

ADD . /pyapp
WORKDIR /pyapp
ENV PATH=/home/ubuntu/.virtualenvs/bin:$PATH
RUN pip install --upgrade pip
RUN pip install --upgrade setuptools
RUN pip install -r requirements.txt

EXPOSE 1883

CMD ['python', '-u', 'app.py']

Any tutorial I 've seen is creating a broker or uses a broker as a service/package. I think what I want to do is much simpler but I haven't found a tutorial. I know that I am missing something basic. Any help is appreciated.

Answer 1

You can not specify the external broker in the docker-compose file, it's for specifying services you are creating with docker.

The best you could do is include the details of the remote broker as environment variables to be passed to your script.

Also there is no point to the EXPOSE 1883 line for your script container because it is a client not a "server".

As mentioned in the comments, you should follow the tutorial fully in order to get a good grounding in how to build composite services with docker-compose before you try and do something different.