container에서 python 로그 출력

container 내부에 python print로 로그를 출력하는 코드가 있다.

docker logs <container>로 확인하면 로그가 출력 되지 않았다.

stackoverflow와 moby 프로젝트에 해결 방안이 나와있다.

https://stackoverflow.com/questions/29663459/python-app-does-not-print-anything-when-running-detached-in-docker

https://github.com/moby/moby/issues/12447#issuecomment-94417192

# main.py

import time

print("App started")

i = 0

while True:

    print("I'm actually alive: {0}".format(i))

    time.sleep(1)

    i += 1 

# Dockerfile

FROM python

COPY main.py .

CMD python -u main.py

# docker image build & docker run

$ docker build --tag logging_test:0.1 

$ docker run -d --name logging_test logging_test:0.1

# docker log 

$ docker logs logging_test --tail 100 --follow

I'm actually alive: 1

I'm actually alive: 2

I'm actually alive: 3

I'm actually alive: 4

I'm actually alive: 5

I'm actually alive: 6

.............