[TripleO] containers logging to stdout

Ben Nemec openstack at nemebean.com
Wed Jan 30 16:57:22 UTC 2019

On 1/30/19 5:23 PM, Sean Mooney wrote:
> On Wed, 2019-01-30 at 07:37 -0500, Emilien Macchi wrote:
>> On Wed, Jan 30, 2019 at 5:53 AM Juan Antonio Osorio Robles <jaosorior at redhat.com> wrote:
>>> Hello!
>>> In Queens, the a spec to provide the option to make containers log to
>>> standard output was proposed [1] [2]. Some work was done on that side,
>>> but due to the lack of traction, it wasn't completed. With the Train
>>> release coming, I think it would be a good idea to revive this effort,
>>> but make logging to stdout the default in that release.
>>> This would allow several benefits:
>>> * All logging from the containers would en up in journald; this would
>>> make it easier for us to forward the logs, instead of having to keep
>>> track of the different directories in /var/log/containers
>>> * The journald driver would add metadata to the logs about the container
>>> (we would automatically get what container ID issued the logs).
>>> * This wouldo also simplify the stacks (removing the Logging nested
>>> stack which is present in several templates).
>>> * Finally... if at some point we move towards kubernetes (or something
>>> in between), managing our containers, it would work with their logging
>>> tooling as well
>> Also, I would add that it'll be aligned with what we did for Paunch-managed containers (with Podman backend) where
>> each ("long life") container has its own SystemD service (+ SystemD timer sometimes); so using journald makes total
>> sense to me.
> one thing to keep in mind is that journald apparently has rate limiting so if you contaiern are very verbose journald
> will actully slowdown the execution of the contaienr application as it slows down the rate at wich it can log.
> this came form a downstream conversation on irc were they were recommending that such applciation bypass journald and
> log to a file for best performacne.

Another thing to check (if you haven't already) is what happens when 
journald restarts. We had an issue with os-collect-config where it died 
when journald was restarted because it started to get EPIPE responses 
when logging.

I don't know if that would be an issue here, but it's something to check.

>> -- 
>> Emilien Macchi

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