Step
First, to add the following dependency
pom.xml
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<!-- for Prometheus endpoint -->
<dependency>
<groupId>io.micrometer</groupId>
<artifactId>micrometer-registry-prometheus</artifactId>
</dependency>
Then to enable endpoints through web access
src/main/resources/application.properties
management.endpoints.web.exposure.include=prometheus,metrics
Add a singleton component
@Component
public class MyMetrics implements MeterBinder {
private final Random random = new Random();
private final AtomicInteger counter = new AtomicInteger();
@Override
public void bindTo(MeterRegistry registry) {
// can any value
Gauge.builder("mymetrics.gauge", this, MyMetrics::getRandom)
.description("MyMetrics gauge")
.register(registry);
// must the same or greater than the value last got, or reset to zero on restart
FunctionCounter.builder("mymetrics.counter", this, MyMetrics::counterGetAndIncrement)
.description("MyMetrics counter")
.register(registry);
}
public double getRandom() {
return random.nextDouble();
}
public int counterGetAndIncrement() {
return counter.getAndIncrement();
}
}
Finally, metric data can be accessed through
/actuator/metrics/mymetrics.counter
{"name":"mymetrics.counter","description":"MyMetrics counter","baseUnit":null,"measurements":[{"statistic":"COUNT","value":9.0}],"availableTags":[]}
/actuator/metrics/mymetrics.gauge
{"name":"mymetrics.gauge","description":"MyMetrics gauge","baseUnit":null,"measurements":[{"statistic":"VALUE","value":0.7618330619753056}],"availableTags":[]}
/actuator/prometheus
# HELP mymetrics_counter_total MyMetrics counter
# TYPE mymetrics_counter_total counter
mymetrics_counter_total 8.0
# HELP mymetrics_gauge MyMetrics gauge
# TYPE mymetrics_gauge gauge
mymetrics_gauge 0.1346348968727723
Beans
Endpoints
Endpoints are annotated with org.springframework.boot.actuate.endpoint.annotation.Endpoint, and they are beans and managed by Spring's BeanFactory.
| Endpoint | Class | Created by |
|---|---|---|
| metrics | org.springframework.boot.actuate.metrics.MetricsEndpoint | org.springframework.boot.actuate.autoconfigure.metrics.MetricsEndpointAutoConfiguration#metricsEndpoint |
| prometheus | org.springframework.boot.actuate.metrics.export.prometheus.PrometheusScrapeEndpoint | org.springframework.boot.actuate.autoconfigure.metrics.export.prometheus.PrometheusMetricsExportAutoConfiguration.PrometheusScrapeEndpointConfiguration#prometheusEndpoint |
org.springframework.boot.actuate.endpoint.web.servlet.WebMvcEndpointHandlerMapping class
This is created by org.springframework.boot.actuate.autoconfigure.endpoint.web.servlet.WebMvcEndpointManagementContextConfiguration#webEndpointServletHandlerMapping. Endpoints information is provided by org.springframework.boot.actuate.endpoint.web.annotation.WebEndpointDiscoverer.
The mapping between path and endpoints will be registered in org.springframework.boot.actuate.endpoint.web.servlet.AbstractWebMvcEndpointHandlerMapping#initHandlerMethods.
It implements org.springframework.web.servlet.HandlerMapping interface, so the instance will be registered into DispatcherServlet during instance construction.
Expose endpoints to JMX
Just add a line into src/main/resources/application.properties
spring.jmx.enabled=true
Association of the endpoints with MBeanServer is by org.springframework.boot.actuate.autoconfigure.endpoint.jmx.JmxEndpointAutoConfiguration.
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