Interesting. And quite annoying that Docker would disable ptrace(2) within its containers by default.
It doesn't if you are running Linux 4.8 or above
Interesting. Is this a change in Docker, or a change in the 4.8 kernel? Any idea why?
Docker detects a different kernel, and that's a result of what I assume is a bug in Linux prior to 4.8 where you could get around a seccomp filter I believe.