CODEWITHSUNDEEP
pythondocker
cheesus
cheesus

Reputation: 1191

Creating a file from a docker container

Wondering how to create a file from inside a docker container.

For example in this project I aim to create a text file. I get confirmation that the process is done, however, there's no txt file.

import logging
import os

logging.basicConfig(format='%(asctime)s - [%(processName)s - %(threadName)s] %(name)s - %(levelname)s - %(message)s', datefmt="%Y-%m-%d %H:%M:%S", level=os.getenv('LOGLEVEL', 'INFO'))  

logger = logging.getLogger(__name__)                     

f= open("example.txt","w+")
for i in range(10):
     f.write("This is line %d\r\n" % (i+1))
f.close() 
logger.info(f'Successfully created text file.')

What am I doing wrong?

Upvotes: 0

Views: 930

Answers (1)

DazWilkin
DazWilkin

Reputation: 40416

The most effective way to share files between a host and a container running on it, is to use volume mounts. It's convenient to keep such volumes distinct.

For argument's sake:

  1. Assuming you're in your project's root, mkdir ./data to create a directory at the same level as your ./src folder.

  2. Change your code (to prove the point) to open("/aha/example.txt","w+"). NB Yes, /aha not /data... keep reading.

  3. Run the container and mount the host's (!) ./data into the container as ./aha: docker run --interactive --tty --volume=${PWD}/data:/aha .... NB This mounts the host's ${PWD}/data into the container as a directory /aha. IIRC you must use ${PWD} to provide an absolute path

  4. Once the Python code completes, the container will have a file called /aha/example.txt and your host (!) should include a file called ${PWD}/data/example.txt

Upvotes: 2

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