Reputation: 1
Get output of Kubernetes pod running a python file
I am running a python script on a docker container inside a kubernetes pod, my script is a mqtt script that when I will be receving a message it prints out the message (i want to be able to save it in the future or send it to another .txt). Right now i am not receiving any outputs in my logs, why is this? I am getting outputs but just about the client connection, new clients connecting etc. I want to get the messages, right now I am just sending "hello", i am receiving this mqtt messages if i do in my terminal mosquitto_pub/mosquitto_sub but not on the output of the pod script. Thank you :)
Dockerfile:
FROM docker.deere.com/python:3.8-slim
RUN pip install paho-mqtt
COPY subscriber.py /subscriber.py
CMD ["python", "./subscriber.py"]
Kubernetes deployment: apiVersion: apps/v1 kind: Deployment metadata: name: mosquitto-broker spec: replicas: 1 selector: matchLabels: app: mqtt-broker template: metadata: labels: app: mqtt-broker spec: containers: - name: mqtt-broker-init image: my-mosquitto:latest ports: - containerPort: 1883 - name: mqtt-subs image: mosquitto-subscriber:latest
python script:
import paho.mqtt.client as mqtt
def on_connect(client, userdata, flags, rc):
print("Connected with result code " + str(rc))
client.subscribe("test/topic")
def on_message(client, userdata, msg):
print("Received message: " + msg.payload.decode())
client = mqtt.Client(mqtt.CallbackAPIVersion.VERSION1, "SubscriberTest")
client.on_connect = on_connect
client.on_message = on_message
client.connect("172.30.0.130", 30988, 60)
client.loop_forever()
pod output:
❯ kubectl logs deployment/mosquitto-broker
Found 4 pods, using pod/mqtt-broker-68c7545bc8-4fs86
Defaulted container "mqtt-broker" out of: mqtt-broker, mosquitto-subs
1708114383: mosquitto version 2.0.18 starting
1708114383: Config loaded from /mosquitto/config/mosquitto.conf.
1708114383: Opening ipv4 listen socket on port 1883.
1708114383: Opening ipv6 listen socket on port 1883.
1708114383: mosquitto version 2.0.18 running
1708114429: New connection from 10.244.0.1:32866 on port 1883.
1708114429: New client connected from 10.244.0.1:32866 as SubscriberTest (p2, c1, k60).
1708114471: New connection from 10.244.0.1:23628 on port 1883.
1708114471: New client connected from 10.244.0.1:23628 as auto-8F54FBAD-6D14-FBB1-6C0B-9E9A5E6101AB (p2, c1, k60).
1708114471: Client auto-8F54FBAD-6D14-FBB1-6C0B-9E9A5E6101AB disconnected.
1708114474: New connection from 10.244.0.1:14961 on port 1883.
1708114474: Client SubscriberTest already connected, closing old connection.
1708114474: New client connected from 10.244.0.1:14961 as SubscriberTest (p2, c1, k60).
1708114475: New connection from 10.244.0.1:18285 on port 1883.
1708114475: Client SubscriberTest already connected, closing old connection.
1708114475: New client connected from 10.244.0.1:18285 as SubscriberTest (p2, c1, k60).
1708114476: New connection from 10.244.0.1:11965 on port 1883.
1708114476: Client SubscriberTest already connected, closing old connection.
1708114476: New client connected from 10.244.0.1:11965 as SubscriberTest (p2, c1, k60).
1708114477: New connection from 10.244.0.1:50342 on port 1883.
1708114477: Client SubscriberTest already connected, closing old connection.
1708114477: New client connected from 10.244.0.1:50342 as SubscriberTest (p2, c1, k60).
1708114604: New connection from 10.244.0.1:48118 on port 1883.
1708114604: New client connected from 10.244.0.1:48118 as auto-6CE6C67F-7CC7-53BD-2627-F3A483F7E774 (p2, c1, k60).
1708114604: Client auto-6CE6C67F-7CC7-53BD-2627-F3A483F7E774 disconnected.
1708115507: New connection from 10.244.0.1:33888 on port 1883.
1708115507: Client SubscriberTest already connected, closing old connection.
1708115507: New client connected from 10.244.0.1:33888 as SubscriberTest (p2, c1, k60).
1708115512: New connection from 10.244.0.1:60569 on port 1883.
1708115512: Client SubscriberTest already connected, closing old connection.
1708115512: New client connected from 10.244.0.1:60569 as SubscriberTest (p2, c1, k60).
1708115565: New connection from 10.244.0.1:14096 on port 1883.
1708115565: New client connected from 10.244.0.1:14096 as auto-451A6E10-1B48-73E8-5BA8-A7606A5D4AC9 (p2, c1, k60).
1708115565: Client auto-451A6E10-1B48-73E8-5BA8-A7606A5D4AC9 disconnected.
1708115567: New connection from 10.244.0.1:15433 on port 1883.
1708115567: New client connected from 10.244.0.1:15433 as auto-3B09DB6C-5735-EEF5-2F17-279A7221E179 (p2, c1, k60).
1708115567: Client auto-3B09DB6C-5735-EEF5-2F17-279A7221E179 disconnected.
1708115929: New connection from 10.244.0.1:23931 on port 1883.
1708115929: New client connected from 10.244.0.1:23931 as auto-7ECB485C-F10A-3DB3-9CB4-DF4F481EFF46 (p2, c1, k60).
1708115929: Client auto-7ECB485C-F10A-3DB3-9CB4-DF4F481EFF46 disconnected.
1708115939: New connection from 10.244.0.1:33648 on port 1883.
1708115939: New client connected from 10.244.0.1:33648 as auto-A4247317-B4D0-1B57-A339-E29F57E70313 (p2, c1, k60).
1708115939: Client auto-A4247317-B4D0-1B57-A339-E29F57E70313 disconnected.
Upvotes: 0
Views: 94
Answers (1)
Reputation: 473
Simply change your Dockerfile's CMD command to:
CMD ["python", "-u", "./subscriber.py"]
You can read more just by typing python -h in your terminal:
-u: force the stdout and stderr streams to be unbuffered;
this option does not affect stdin; also PYTHONUNBUFFERED=x
Unbuffered streams in Python immediately transfer data without storing it in a buffer. This means that data is directly read or written from the underlying source or destination as soon as it is available, without waiting for the buffer to fill.
This is a "must-be thing" in any Docker image with Python.
Upvotes: 1