CTDB: simple/90_debug_hung_script.sh test fails on some machines

[Andrew Bartlett]

On Wed, 2018-11-14 at 14:24 +1300, Tim Beale via samba-technical wrote:
> Hi,
> 
> I noticed a problem trying to run the samba_build_ctdb test on the
> rackspace machines. The tests/simple/90_debug_hung_script.sh test-case
> seems to reliably fail.
> 
> I could reproduce the failure by running the ctdb autobuild on my PC.
> Basically the test is failing because the 'cat "/proc/${pid}/stack"' in
> debug-hung-script.sh fails (Operation not permitted). The reason for the
> failure seems to be the Yama ptrace_scope setting on the host machine.
> https://www.kernel.org/doc/Documentation/security/Yama.txt
> 
> My PC had kernel.yama.ptrace_scope set to 1. If I set it to zero, then
> the CTDB test passes. It seems like the gitlab CI machines must use a
> ptrace_scope=0 setting.

G'Day Martin,

Specifically, while the 'shared' runners must have a more liberal
setting (as they pass), runners started by the Samba Team at Rackspace
use a different kernel-side configuration.  

We are testing out using Rackspace runners for the whole CI to ensure
we don't strictly rely on the shared resources (which are free - to us
- small VMs only available because we are on gitlab.com).

While we are also looking to change that the ptrace limitations on
'our' machines, in the meantime it would be nice if the test was a
little more accepting. 

Thanks,

Andrew Bartlett

-- 
Andrew Bartlett
https://samba.org/~abartlet/
Authentication Developer, Samba Team         https://samba.org
Samba Development and Support, Catalyst IT   
https://catalyst.net.nz/services/samba