Docker Details

Docker Details - dumb-init

If you don’t control the “init” process of docker then you are doing it wrong. But don’t worry there is an easy fix. Before I explain the solution, I should explain the issue. Almost every process you run in Linux will likely run at least 1 child process. And Linux expects that every parent will properly care for its children by propagating kernel signals like SIGTERM, and by cleaning up child zombie processes. If all else fails the Linux init process will do that on behalf of Linux and all is happy.

However, programmers generally don’t know the requirements of dealing with child processes, and linux clean up after itself so unless you already know what to do testing won’t show issues. The issue comes because Docker doesn’t provide an init process for the container, so your child processes will not get signals, zombies will be created, and eventually things will terminate uncleanly.