[Hawkular-dev] inventory hierarchy

[Lukas Krejci]

IMHO, technically, you don't need the hierarchy to report the metrics in your 
examples.

<metric-set name="my-metrics">
   <metric name="active-sessions" 
resource="/deployment=hwk.ear/subdeployment=alerts.war/subsystem=undertow"/>
   <metric name="request-count" 
resource="/deployment=hwk.ear/subdeployment=alerts.war/subsystem=undertow/servlet=App/"
</metric-set>

Now if you want to report the resources, too, then yes, hierarchy is needed.
But there is a distinction between metrics and resources and I think we should 
keep them as separate concepts - metrics maybe logically included in resources 
but they should exist as standalone entities not inherently tied to resources.

If for nothing else then for the fact that we somehow have to report the 
metrics to hawkular-metrics, where there is no concept of a resource (and I 
think there never should be).

Now to the way how you would define a resource hierarchy.

IMHO the way we've done it in RHQ is more or less right. You define the types 
of the resources, the possible "hierarchizations" (in RHQ specified either 
implicitly by the nesting of the definitions or explicitly by "runs-inside") 
and then you discover the resources as "instances" of those types.

Also if you rather think of types than the concrete instances, the problem of 
the "wildcards" that Heiko is highlighting finds a comfortable place in the 
design.

With that in mind, I think something along the lines of the following could 
work:

- metric sets are basically equivalent to hawkular inventory resource types:

<resource-type name="my-metrics">
   <path expr="/deployment=(.*)/subdeployment=(.*)"/>
   
   <!-- groups in the path's expr -->
   <resource-name>${path.1}-${path.2}</resource-name>
   
   <metric name="active-sessions" subpath="/subsystem=undertow"/>
   <metric name="request-count" subpath="/subsystem=undertow/servlet=App"/>
   <metric name="blah" path="/deployment=${path.1}/something-else"/>
   <parents>your-metrics, his-metrics</parents>
</resource-type>

- managed resource sets are I think no longer needed

- managed servers reference resource types they want managed on the servers.

The resource type definition above basically combines the resource type def as 
it existed in RHQ (of sorts) with a simple discovery by querying the 
management model and matching it with the regular expr.

On Monday, April 20, 2015 15:56:32 John Mazzitelli wrote:
> Well, after staring at things today, I am coming to the conclusion I
> probably should re-arrange my agent configuration before I get too far
> ahead. Need to know what people think.
> 
> The current hawkular monitor agent defines things like this - you define
> your metric definitions and then you define where your servers are
> (host/port) and what metrics to collect from those servers. A very small
> agent config would be something like:
> 
> <metric-set-dmr name="my-metrics">
>    <metric-dmr name="my-threads"
> resource="/core-service=platform-mbean/type=threading"
> attribute="thread-count" </metric-set-dmr>
> 
> <managed-resources>
>     <remote-dmr name="my-server" host="myhost" port="9990"
> metricSets="my-metrics" /> </managed-resources>
> 
> But after looking at the kinds of metrics we want to collect, I think we
> need to introduce some intermediate data - specifically, resource
> hierarchy.
> 
> For example, if you look at Kettle (which has a pretty interesting and
> non-trivial DMR hierarchy) there are things like this:
> 
> Alerts EAR (/deployment=hawkular-alerts-ear-1.0.ear)
> 
>  \-- Alerts REST WAR
> (/deployment=hawkular-alerts-ear-1.0.ear/subdeployment=hawkular-alerts-rest
> .war/)
> 
>       \-- Undertow Subsystem
> (/deployment=hawkular-alerts-ear-1.0.ear/subdeployment=hawkular-alerts-rest
> .war/subsystem=undertow/)
> 
>            \-- METRIC: active-sessions
>            \-- METRIC: sessions-created
> 
>            \-- Servlet
> (/deployment=hawkular-alerts-ear-1.0.ear/subdeployment=hawkular-alerts-rest
> .war/subsystem=undertow/servlet=org.hawkular.alerts.rest.HawkularAlertsApp/)
> 
>                 \-- METRIC: max-request-time
>                 \-- METRIC: min-request-time
>                 \-- METRIC: request-count
> 
> There's also EJB3 subdeployments under the EAR which have singleton-beans
> that have execution-time and other invocation metrics.
> 
> So, clearly, I think there has to be something like managed entities in
> between those endpoint servers and metrics in the agent configuration.
> Essentially, we need to define resources in the config.
> 
> I was thinking of renaming "managed-resources" to "managed-servers" and then
> have "managed-resources" in between servers and metrics:
> 
> <metric-set-dmr name="my-undertow-metrics">
>    <metric-dmr name="Active Sessions" attribute="active-sessions" />
>    <!-- resource denotes a child resource under the resource that has this
> metric defined --> <metric-dmr name="Servlet Requests"
> resource="/subsystem=undertow/servlet=org.hawkular.alerts.rest.HawkularAler
> tsApp" attribute="request-count" /> </metric-set-dmr>
> 
> <managed-resource-set-dmr = "Alerts Application">
>    <resource-dmr name"Alerts EAR"
>                  path="/deployment=hawkular-alerts-ear-1.0.ear"
>    <resource-dmr name="Alerts WAR"
>                  parent="Alerts EAR"
>                  path="/subdeployment=hawkular-alerts-rest.war"
>                  metricSets="my-metrics"/>
> </managed-resource-set-dmr>
> 
> <managed-servers>
>     <remote-dmr name="my-server" host="myhost" port="9990"
> resourceSets="Alerts Application" /> </managed-servers>
> 
> One difference between this and RHQ is I don't define those low-low level
> resources as separate resources (in RHQ I would have to define the undertow
> subsystem as a child under the WAR and then a servlet under the undertow
> resource). There is only the EAR and the WAR resource with the low level
> metrics from undertow and the servlet being "assigned" or linked to the WAR
> resouce.
> 
> So the Hawkular inventory hierachy would be this (compare with the Wildfly
> hierarchy):
> 
> Alerts EAR
> 
>  \-- Alerts WAR
> 
>       \-- METRICS: Active Sessions (coming from undertow)
>       \-- METRICS: Servlet Requests (coming from the servlet inside
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