Signals not handled properly

[robbertkl]

Running supervisord within dockerize I've noticed the following issues:

When dockerize receives SIGINT (e.g. ctrl-c in an interactive docker container) the following happens:

• dockerize outputs Received signal: interrupt
• dockerize forwards this signal to its child process (supervisord in my case)
• supervisord gracefully terminates its "programs" and exits
• dockerize outputs Command finished successfully.
• (so far so good, now for the unexpected)
• dockerize doesn't exit
• after 10 seconds, dockerize outputs Killing command due to timeout. and exits

Seems to me the 10 second wait has no function, the child process is already gone (which dockerize noticed) and dockerize should exit right away.

Another issue occurs when dockerize receives SIGTERM (e.g. on docker stop):

• dockerize exits immediately without any output
• signal is not forwarded to child process (supervisord) and not waited on
• supervisord (and its running "programs") don't get a chance to gracefully shutdown
• actually the child process (supervisord and its children) is not killed at all and keeps running; however, the container is destroyed along with any processes in it, similar to a SIGKILL to those processes (unclean shutdown)

In contrast, when supervisord receives SIGTERM, it forwards this to its running programs and waits for them to exit cleanly, killing them with SIGKILL if it takes too long. IMO dockerize should do something similar.

[jwilder]

@robbertkl The timeout should be fixed in v0.0.4. The SIGTERM/SIGKILL handling should also be fixed, but you need to make sure your Dockerfile CMD is using the exec form;

CMD ["dockerize", "-template", ...]

vs.

CMD dockerize -template ....

The latter actually invokes /bin/sh dockerize which will not forward signals to dockerize correctly. You can run docker exec <container> ps -ef to see if dockerize is actually pid 1 or if /bin/sh is.

[robbertkl]

Yes, I'm aware of the exec form (and the consequences). Awesome job on the improvements / fixes, I'll give them a spin soon!