Using timeout with docker run from within script

Question

In my Travis CI, part of my verification is to start a docker container and verify that it doesn't fail within 10 seconds. I have a yarn script docker:run:local that calls docker run -it <mytag> node app.js.

If I call the yarn script with timeout from a bash shell, it works fine:

$ timeout 10 yarn docker:run:local; test $? -eq 124 && echo "Container ran for 10 seconds without error"

This calls docker run, lets it run for 10 seconds, then kills it (if not already returned). If the exit code is 124, the timeout did expire, which means the container was still running. Exactly what I need to verify that my docker container is reasonably sane.

However, as soon as I run this same command from within a script, either in a test.sh file called from the shell, or if putting it in another yarn script and calling yarn test:docker, the behaviour is completely different. I get:

ERRO[0000] error waiting for container: context canceled

Then the command hangs forever, there's no 10 second timeout, I have to ctrl-Z it and then kill -9 the process. If I run top I now have a docker process using all my CPU forever. If using timeout with any other command like sleep 20 && echo "Finished sleeping", this does not happen, so I suspect it may have something to do with how docker works in interactive mode or something, but that's only my guess.

What's causing timeout docker:run to fail from a script but work fine from a shell and how do I make this work?

Actually removing -it completely seems to have resolved this, and I don't actually need interactive mode to start my application. Thanks. — JHH
– JHH, Commented Dec 10, 2020 at 15:54

Raman Sailopal · Accepted Answer · 2020-12-10 15:57:50Z

1

Looks like running docker in interactive mode is causing the issue.

Run docker in detached more by removing the -it and allowing it to run in default detached mode or specify -d instead of -it and so:

docker run -d <mytag> node

or

docker run <mytag> node

answered Dec 10, 2020 at 15:57

Raman Sailopal

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1 Comment

Turkhan Badalov Mar 30 at 16:56

Not sure what signal the timeout command uses, on Mac I had to pass -s 9 and -k 2 parameters to force kill after 2 seconds since the timeout if the app keeps running. Also, for future reference, on Mac the command is gtimeout and needs to be installed via brew install coreutils. So the final command looked like this gtimeout -k 2 -s 9 8 docker run -e ENV1=VAL1 <docker_image_id>

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