<#import "/templates/guide.adoc" as tmpl>
<#import "/templates/kc.adoc" as kc>
<#import "/templates/options.adoc" as opts>
<#import "/templates/links.adoc" as links>

<@tmpl.guide
title="Enabling {project_name} Metrics"
summary="Learn how to enable and expose metrics from the server"
includedOptions="metrics-enabled http-metrics-* cache-metrics-*">

{project_name} has built in support for metrics. This {section} describes how to enable and configure server metrics.

== Enabling Metrics

It is possible to enable metrics using the build time option `metrics-enabled`:

<@kc.start parameters="--metrics-enabled=true"/>

== Querying Metrics

{project_name} exposes metrics at the following endpoint on the management interface at:

* `/metrics`

For more information about the management interface, see <@links.server id="management-interface" />.
The response from the endpoint uses a `application/openmetrics-text` content type and it is based on the Prometheus (OpenMetrics) text format. The snippet below
is an example of a response:

[source]
----
# HELP base_gc_total Displays the total number of collections that have occurred. This attribute lists -1 if the collection count is undefined for this collector.
# TYPE base_gc_total counter
base_gc_total{name="G1 Young Generation",} 14.0
# HELP jvm_memory_usage_after_gc_percent The percentage of long-lived heap pool used after the last GC event, in the range [0..1]
# TYPE jvm_memory_usage_after_gc_percent gauge
jvm_memory_usage_after_gc_percent{area="heap",pool="long-lived",} 0.0
# HELP jvm_threads_peak_threads The peak live thread count since the Java virtual machine started or peak was reset
# TYPE jvm_threads_peak_threads gauge
jvm_threads_peak_threads 113.0
# HELP agroal_active_count Number of active connections. These connections are in use and not available to be acquired.
# TYPE agroal_active_count gauge
agroal_active_count{datasource="default",} 0.0
# HELP base_memory_maxHeap_bytes Displays the maximum amount of memory, in bytes, that can be used for memory management.
# TYPE base_memory_maxHeap_bytes gauge
base_memory_maxHeap_bytes 1.6781410304E10
# HELP process_start_time_seconds Start time of the process since unix epoch.
# TYPE process_start_time_seconds gauge
process_start_time_seconds 1.675188449054E9
# HELP system_load_average_1m The sum of the number of runnable entities queued to available processors and the number of runnable entities running on the available processors averaged over a period of time
# TYPE system_load_average_1m gauge
system_load_average_1m 4.005859375

...
----

== Available Metrics

The table below summarizes the available metrics groups:

[%autowidth]
|===
|Metric | Description

|System
|A set of system-level metrics related to CPU and memory usage.

|JVM
|A set of metrics from the Java Virtual Machine (JVM) related to GC, and heap.

|Database
|A set of metrics from the database connection pool, if using a database.

|HTTP
|A set of global and individual metrics from the HTTP endpoints

|Cache
|A set of metrics from Infinispan caches. See <@links.server id="caching"/> for more details.

|===

</@tmpl.guide>
