Re: [HTCondor-users] docker universe and centos 6

[Todd Tannenbaum <tannenba@xxxxxxxxxxx>]

On 8/29/2019 2:40 PM, Dimitri Maziuk wrote:
> On 8/29/19 2:29 PM, Todd Tannenbaum wrote:
> 
>> Just a guess:  Perhaps on barracuda user condor is not in a member of
>> the docker group...  what does "groups condor" say on barracuda?  If
>> condor is not in the docker group, then HasDocker should not be true
>> since HTCondor could not launch any containers...
> 
> Well condor's not in docker group on any of them but on all centos 7
> nodes HasDocker is true and on all 3 centos 6 nodes HasDocker is false.
> 

The test HTCondor uses to decide if HasDocker should be True or False is 
to to test if spawning 'docker info' is successful as user condor, where 
the "docker" command/path is actually whatever condor_config_val DOCKER 
says.   Since docker info contacts dockerd, normally this only succeeded 
if the config knob DOCKER points to the docker command, dockerd is 
running/responding, and user 'condor' has permission to talk to the 
dockerd.  If condor is not in the docker group and HasDocker is true, 
perhaps you installed docker in such a way that any user can issue 
docker commands (kinda scary)?   At any rate, hope this explanation 
helps to troubleshoot why it is not working. Also the HTCondor 
StarterLog or StartdLog may have some docker failure hints...


>> Also FWIW... docker on centos 6 is pretty buggy because the kernel is so
>> old, which is why Docker itself claims it needs centos 7 or above... I
>> guess if you updated the kernel on your centos 6 machines maybe you'd be
>> ok, but we encountered a lot of bugs trying to use Docker on centos 6...
> 
> Right, but since you guys are not offering alpine builds, those of us
> allergic to systemd don't have too many options... Looks like we have to
> run condor in a centos 7 container in order to run a docker container in
> condor.
> 

I guess that would be one way of running HTCondor on Alpine (we may be 
working soon on creating some 'official' HTCondor docker hub images)... 
Or perhaps you could build HTCondor on Alpine from source (not sure if 
musl libc vs glibc will be a headache for building or not)...  Or 
perhaps try running Centos 6 with an upgraded kernel from ElRepo to give 
a chance that Docker will run ok (although one day Centos 6 security 
updates will stop).

Or just decide to take some systemd antihistamines and make friends with 
it since Centos, Ubuntu, Debian, etc, have all drank the kool-aid, so it 
will likely be around a long time :)

regards
Todd