'How is python importing a package in Docker without installing it in the container first?
I have a new developer on our team and asked her to build a simple proof of concept of a Python client for an Apache Pulsar cluster in Docker.
What's got me flummoxed is that no where did she include a some step to install python package requirements. Normally, I have always had a Dockerfile with a line like:
# Install pip requirements
COPY requirements.txt .
RUN python -m pip install -r requirements.txt
She however, she just has a docker-compose.yml file that looks like:
version: "3"
services:
pulsar:
image: apachepulsar/pulsar:latest
command: ["bin/pulsar", "standalone"]
volumes:
- ./modules:/app
producer:
image: apachepulsar/pulsar:latest
volumes:
- ./modules:/app
command: ["python", "/app/producer.py"]
depends_on:
- pulsar
consumer:
image: apachepulsar/pulsar:latest
command: ["python", "/app/consumer.py"]
volumes:
- ./modules:/app
depends_on:
- pulsar
There's no command anywhere to install packages. And yet she has a simple script where she imports pulsar a package to facilitate interacting with Apache Pulsar and it runs and behaves fine on my machine. See below for example:
#!python
import pulsar
print('------ consumer output')
client = pulsar.Client('pulsar://pulsar:6650')
consumer = client.subscribe('my-topic', 'my-subscription')
while True:
msg = consumer.receive()
try:
print("Received message '%s' id='%s'", msg.data().decode('utf-8'), msg.message_id(), flush=True)
consumer.acknowledge(msg)
except:
consumer.negative_acknowledge(msg)
client.close()
How is this possible? I run a docker system prune thinking that maybe I had an image with the packages installed somehow? (Not sure that's even possible). But even after that the program still works.
Solution 1:[1]
Sources
This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.
Source: Stack Overflow
| Solution | Source |
|---|---|
| Solution 1 | Tim Spann |