Re: [HTCondor-users] condor_rm & the docker universe

[Todd Tannenbaum <tannenba@xxxxxxxxxxx>]

On 7/30/2015 1:53 PM, Brian Bockelman wrote:
> > On Jul 30, 2015, at 10:01 AM, andrew.lahiff@xxxxxxxxxx wrote:
> >
> > Hi Greg,
> >
> > Ok, I didn't realized it worked like this - I had assumed HTCondor
> > would do something like "docker stop", rather than send a signal to
> > the actual executable running inside the container. Isn't this
> > rather unsafe? It makes it very easy for people to run jobs which
> > escape HTCondor's control - according to HTCondor the job has been
> > killed but the Docker container continues running for as long as it
> > wants.
>
> PID 1 is a very special creature.
>
> In addition to having the somewhat-bizarre signal handling mentioned
> below (PS Greg - why donât we use the same trick here as in vanilla
> universe to avoid the problem there?)

Hi Brian,

Do you mean why don't we invoke the job via the 
$(LIBEXEC)/condor_pid_ns_init wrapper like we do when running a vanilla 
job in a private pid namespace?  I asked Greg the same thing.  The issue 
is condor_pid_ns_init is dynamically linked with a bunch of libraries we 
cannot ensure will exist in the docker image.  I suppose one way around 
this would be to statically link condor_pid_ns_init; not sure how 
involved that change is to the build/cmake process.  Looking at the 
source for condor_pid_ns_init (see https://goo.gl/P8ejqY - Andrew, you 
may find this interesting...) , it doesn't look like it really uses much 
beyond libc (i.e. doesn't use/need HTCondor libraries per se), so maybe 
this isn't as hard as it may seem.  Of course an ldd of 
condor_pid_ns_init shows it is dynamically linked with all kinds of 
things that aren't really needed, but I think that is just an artifact 
of our cmake setup.

regards
Todd

--
Todd Tannenbaum <tannenba@xxxxxxxxxxx> University of Wisconsin-Madison
Center for High Throughput Computing   Department of Computer Sciences
HTCondor Technical Lead                1210 W. Dayton St. Rm #4257
Phone: (608) 263-7132                  Madison, WI 53706-1685