Apport, installed on the docker-worker host, sets /proc/sys/kernel/core_pattern to |/usr/share/apport/apport %p %s %c %P. What this does in practice, is that everything that crashes in a docker container makes the *host* run that command, which then processes the crash, maybe even exfiltrating data to canonical (pure speculation, and that's not why I'm filing this bug anyways, just a possible additional reason to want to have this removed). What this means in practice is that there is *absolutely* no way to get a core dump of crashing processes in a docker container. And while one may be able to do some kinds of jumping through hoops to attach a debugger (good luck with that, with ptrace being either disabled or prevented for processes not in the ancestry or the crashing process), even when you somehow succeed, running with the debugger attached changes timings. In my case, chasing a high frequency intermittent crash, attaching a debugger just makes the crash go away... Uninstalling or disabling apport on the host would leave the default of "core", which would create the core dump in the working directory of the crashing process, which is good enough.

This seems like low-hanging fruit...

https://github.com/taskcluster/docker-worker/pull/356 is up for review. Depends on some other PRs. But it should hopefully land soonish.

Commit pushed to master at https://github.com/taskcluster/docker-worker https://github.com/taskcluster/docker-worker/commit/7305fd1e0635042fa7d5b53343a5a3985d65fc4c Remove apport (bug 1413823)

I'm gonna call this closed since the commit landed in docker-worker. When it will get deployed, I'm not sure.

This is supposed to be deployed, but apparently didn't work: # cat /proc/sys/kernel/core_pattern |/usr/share/apport/apport %p %s %c %d %P (in one-click loaners on both gecko-t-linux-large and gecko-1-b-linux workers)

:gps, is this worth working on a fix? I see you've been needinfo'd for 4 months :)

I think it is still worth fixing because it makes debugging crashes on TC workers extremely difficult. But I'm not actively working on it. (I stopped hacking on all things docker-worker a bit ago. And I have little desire to go back since apparently docker-worker doesn't have much of a future.)