从Docker中运行的进程返回日志文件

Question

I'm a total newbie to docker, and am having trouble on how to approach this problem. Consider this super simplified cli tool that produces a log when ran with docker run .

import click
import logging

logging.basicConfig(filename='log.log')
logger = logging.getLogger(__name__)

@click.group()
@click.version_option('1.0')
def cli():
    '''docker_cli with docker test'''


@cli.command('run')
@click.argument('name', default='my name')
def run(name):
    logger.info("running 'run' within docker")
    print('Hello {}'.format(name))

And my dockerfile is as follows:

FROM python:3.5-slim

LABEL maintainer="Boudewijn Aasman"
LABEL version="1.0"

ENV config production

RUN mkdir /docker_cli
COPY docker_cli ./docker_cli
COPY setup.py .

RUN python setup.py install

CMD ["cli", "run"]

If I execute the container using:

docker run cli_test cli run world

how do I retrieve the log file that gets created during the process? The container exits immediately after the command print out 'Hello world'. My assumption is using a volume, but not sure how to make it work.

Answer 1

Have you tried this?

docker logs cli_test

---

EDIT: Sorry, I missed this the first time, but in order for this to work, you'll have to log to STDERR, not to a log file. (Thanks @Gonzalo Matheu for pointing this out.) To get it working, it should be as simple as making this small additional change:

logging.basicConfig()  # note no file name

Answer 2

You can either share a local directory:

docker run -v full-path-your-local-dir:. cli_test cli run world

Or create a docker volume

docker volume create cli_test_volume
docker run -v cli-test_volume:. cli_test cli run world
docker volume inspect cli_test_volume # will show where the volume is located.

For both of these approaches you will need to write the logs in a different path than the application . Otherwise, app code will be overwritten by the shared volume.

There is another alternative, which is to copy files from the container using create and cp :

docker create --name cli_test_instance cli_test run world
docker start  cli_test_instance 
docker cp cli_test_instance:log.log .