Re: Systemd socket inheritance fails with “not a socket file descriptor”

[Amir Yalon <amiryal@yxejamir.net>]

Christos Trochalakis wrote:
> Ok, this is my theory, systemd correctly passes the sockets and the
> environment to the process, but Amir is using rvm which probably runs
> one more exec than usual. In this extra step rvm/ruby closes the fds for
> security reasons but the ENV variables remain. In the newly forked ruby
> process the timer gets fd=3 (which is now consider internal) and when
> unicorn tries to example fd=3 breaks.

Very plausible!

I ran a few straces to confirm at least part of the theory, and it turns
out RVM runs not one, but 20 more exec than usual. :)

The way my application is launched with RVM:

$ strace -c -e trace=execve /usr/local/rvm/bin/rvm default exec ruby -e
''
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
  0.00    0.000000           0        21        16 execve
------ ----------- ----------- --------- --------- ----------------
100.00    0.000000                    21        16 total

Using system Ruby:

$ strace -c -e trace=execve ruby -e ''
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
  0.00    0.000000           0         1           execve
------ ----------- ----------- --------- --------- ----------------
100.00    0.000000                     1           total

Using RVM ruby without RVM wrapper:

$ strace -c -e trace=execve /usr/local/rvm/rubies/default/bin/ruby -e ''
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
  0.00    0.000000           0         1           execve
------ ----------- ----------- --------- --------- ----------------
100.00    0.000000                     1           total

I will try to run my app using the 3rd method and report back as soon as
I can.

Thanks,
Amir