https://bugzilla.redhat.com/show_bug.cgi?id=1087720
--- Comment #10 from Matthew Heon mheon@redhat.com --- After further testing, I've managed to reproduce being unable to send signals 19, 18, and 27 to the container via --sig-proxy.
This seems to be a Golang issue. I implemented a trivial signal-catching test program in Go and tested it with signals 1-31, and obtained identical results to Docker aside from Signal 17 (discarded on Docker, caught by my test program).
A brief summary of signals Docker does not play well with: - Signal 17, SIGCHLD, deliberately caught and discarded. Makes no sense to pass this into a container. - Signal 18, SIGCONT, seems to be Golang issue - Signal 19, SIGSTOP, unmaskable signal - cannot be caught - Signal 27, SIGPROF, seems to be Golang issue
Worth noting that the "docker kill" command should be able to send any of these without issue. If we have any general docs for Docker, we may want to recommend avoiding proxying signals in favor of docker kill whenever possible.