[jboss-jira] [JBoss JIRA] (WFCORE-4238) Distinguish type of WildFly metrics

[Jeff Mesnil (Jira)]

     [ https://issues.jboss.org/browse/WFCORE-4238?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jeff Mesnil updated WFCORE-4238:
--------------------------------
    Fix Version/s: 8.0.0.Alpha


> Distinguish type of WildFly metrics
> -----------------------------------
>
>                 Key: WFCORE-4238
>                 URL: https://issues.jboss.org/browse/WFCORE-4238
>             Project: WildFly Core
>          Issue Type: Enhancement
>          Components: Management
>            Reporter: Jeff Mesnil
>            Assignee: Jeff Mesnil
>            Priority: Major
>             Fix For: 8.0.0.Alpha
>
>
> WildFly metrics needs to be exposed to Prometheus.
> In the current implementation of the microprofile-metrics-smallrye subsystems, all WildFly metrics are exposed as Gauges[1] which represents a single numerical value that can goes up and down and may have a unit (e.g. bytes or seconds).
> We should be able to represent more correctly some metrics as Counters[2] which are "cumulative metric that represents a single monotonically increasing counter whose value can only increase or be reset to zero on restart"
> In its current state, metadata associated to WildFly metrics does not able to distinguish gauges and counters.
> * If the metric has a measurement unit (specified by org.jboss.as.controller.AttributeDefinition#getMeasurementUnit), it can be represented as a Gauge
> * If the metric does not have a measurement unit, we can not reliably decide between gauge and counters.
> For example, the message-count[3] for the jms-queue resource is a *gauge* as this number will can go up (when messages are produced faster than they are consumed) or down (when messages are consumed faster than they are produced) to 0.
> Conversely, the  messages-added[4] for the same jms-queue or request-count[4] for Undertow servlet are *counters* as they will always increase.
> Only the subsystem developers is able to specify which type of metrics it provides.
> I propose that we add 2 new values to org.jboss.as.controller.registry.AttributeAccess.Flag to let the subsystem developers provides this information:
> GAUGE_METRIC
> COUNTER_METRIC
> In the absence of the COUNTER_METRIC, the metric would be identified as a Gauge.
> We had the GAUGE_METRIC value so that the subsystem developer can explicitly state that a metric is a gauge which is helpful when the same resource (e.g. jms-queue) provides metrics of the 2 different types (e.g. message-counter vs messages-added).
> This API change is backwards compatible.
> These 2 flags remain optional and would only be checked when the attribute definition is registered as a metric with org.jboss.as.controller.registry.ManagementResourceRegistration#registerMetric.
> [1] https://prometheus.io/docs/concepts/metric_types/#gauge
> [2] https://prometheus.io/docs/concepts/metric_types/#counter
> [3] http://wildscribe.github.io/WildFly/14.0/subsystem/messaging-activemq/server/jms-queue/index.html#attr-message-count
> [4] http://wildscribe.github.io/WildFly/14.0/subsystem/messaging-activemq/server/jms-queue/index.html#attr-messages-added
> [5] http://wildscribe.github.io/WildFly/14.0/deployment/subsystem/undertow/servlet/index.html#attr-request-count



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