[openstack-dev] Logging format: let's discuss a bit about default format, format configuration and so on

Doug Hellmann doug at doughellmann.com
Fri Nov 3 17:58:19 UTC 2017

Excerpts from Cédric Jeanneret's message of 2017-11-01 14:54:34 +0100:
> Dear Stackers,
> While working on my locally deployed Openstack (Pike using TripleO), I
> was a bit struggling with the logging part. Currently, all logs are
> pushed to per-service files, in the standard format "one line per
> entry", plain flat text.
> It's nice, but if one is wanting to push and index those logs in an ELK,
> the current, default format isn't really good.
> After some discussions about oslo.log, it appears it provides a nice
> JSONFormatter handler¹ one might want to use for each (python) service
> using oslo central library.
> A JSON format is really cool, as it's easy to parse for machines, and it
> can be on a multi-line without any bit issue - this is especially
> important for stack traces, as their output is multi-line without real
> way to have a common delimiter so that we can re-format it and feed it
> to any log parser (logstash, fluentd, …).
> After some more talks, olso.log will not provide a unified interface in
> order to output all received logs as JSON - this makes sens, as that
> would mean "rewrite almost all the python logging management
> interface"², and that's pretty useless, since (all?) services have their
> own "logging.conf" file.
> That said… to the main purpose of that mail:
> - Default format for logs
> A first question would be "are we all OK with the default output format"
> - I'm pretty sure "humans" are happy with that, as it's really
> convenient to read and grep. But on a "standard" Openstack deploy, I'm
> pretty sure one does not have only one controller, one ceph node and one
> compute. Hence comes the log centralization, and with that, the log
> indexation and treatments.
> For that, one might argue "I'm using plain files on my logger, and
> grep-ing -r in them". That's a way to do things, and for that, plain,
> flat logs are great.
> But… I'm pretty sure I'm not the only one wanting to use some kind of
> ELK cluster for that kind of purpose. So the right question is: what
> about switching the default log format to JSON? On my part, I don't see
> "cons", only "pros", but my judgment is of course biased, as I'm "alone
> in my corner". But what about you, Community?
> - Provide a way to configure the output format/handler
> While poking around in the puppet modules code, I didn't find any way to
> set the output handler for the logs. For example, in puppet-nova³ we can
> set a lot of things, but not the useful handler for the output.
> It would be really cool to get, for each puppet module, the capability
> to set the handler so that one can just push some stuff in hiera, and
> Voilà, we have JSON logs.
> Doing so would allow people to chose between the default  (current)
> output, and something more "computable".

Using the JSON formatter currently requires setting a logging
configuration file using the standard library configuration format
and fully specifying things like log levels, handlers, and output
destination. Would it make sense to add an option in oslo.log to
give deployers an easier way to enable the JSON formatter?


> Of course, either proposal will require a nice code change in all puppet
> modules (add a new parameter for the foo::logging class, and use that
> new param in the configuration file, and so on), but at least people
> will be able to actually chose.
> So, before opening an issue on each launchpad project (that would be…
> long), I'd rather open the discussion in here and, eventually, come to
> some nice, acceptable and accepted solution that would make the
> Openstack Community happy :).
> Any thoughts?
> Thank you for your attention, feedback and wonderful support for that
> monster project :).
> Cheers,
> C.
> ¹
> https://github.com/openstack/oslo.log/blob/master/oslo_log/formatters.py#L166-L235
> ²
> http://eavesdrop.openstack.org/irclogs/%23openstack-oslo/%23openstack-oslo.2017-11-01.log.html#t2017-11-01T13:23:14
> ³ https://github.com/openstack/puppet-nova/blob/master/manifests/logging.pp

More information about the OpenStack-dev mailing list