Open Stack

Hi Kolla devs

The other day inc0 said that we would like "central logging" to be
optional in Mitaka, and still use Rsyslog and keep the current
behavior if "central logging" is disabled.

I would like to propose an alternative, where we do remove Rsyslog as
planned in the spec.

I like the idea of an enable_central_logging switch, because it makes
sense to me that an operator have the possibility to NOT centralize
his logs in Elasticsearch (or anywhere else).

When enable_central_logging is false I suggest to just not deploy
Heka, Elasticsearch and Kibana. (Rsyslog would not be deployed
either.)

So when enable_central_logging is false the OpenStack services will
still write their logs in the "log" named volume
(/var/lib/docker/volumes/log/_data), but no one will read/process
these logs.  They will just sit there at the disposal of the operator.

For services that log to Syslog (HAProxy and Keepalived) we won't
collect their logs if enable_central_logging is false, but these
services' logs are not collected today, so no regression there.

I think this would make a simple alternative.

Thoughts?