[EnMasse] Dispatch router metrics to hawkular

[Ulf Lilleengen]

Hi,

I have been working on exporting metrics from EnMasse, and have this 
working for Artemis (using jolokia). I would also like to export metrics 
from the qpid dispatch router.

Exposing metrics to the hawkular agent is either done using jolokia, 
prometheus or custom JSON. Jolokia is mostly relevant for java 
components, and custom JSON is ... custom.

Prometheus has a nice python library that can be used for exposing 
metrics over an http interface that will be polled every X seconds by 
the hawkular agent (running on all hosts). So here are a few 
alternatives for exposing the metrics:

a) A component running in the admin pod that will export metrics for all 
routers (using AMQP management to collect them from all routers)
b) A component running alongside each router that will report metrics 
for that router only (using AMQP management to collect them)
c) As alternative b), but as a compile-time plugin for the router

I think a) could be useful for both reporting metrics and as an API for 
the enmasse console. The disadvantage I think would be that metric 
collection depends on a single component that could limit the 
scalability in a large network and possibly impact the other AMQP 
traffic. It would also be working differently from broker metrics 
reporting and (likely) other enmasse components.

b) is probably the quickest way to get something working. It only 
involves talking over the local interface, and leaves scalability 
concerns of metric collection to hawkular. The disadvantage is that we 
have to run an extra container (although very light-weight) in each 
router pod.

I think c) would benefit additional users deploying the dispatch router 
themselves and that wants to use it with prometheus-compatible 
monitoring tools. At the same time I have a hunch that having a http 
interface integrated like that is controversial in AMQP-land :)

wdyt?

-- 
Ulf