How to emit metrics in Java

To emit metrics with the Java SDK, use MicrometerClientStatsReporter class to integrate with Micrometer MeterRegistry configured for your metrics backend. Micrometer is a popular Java framework that provides integration with Prometheus and other backends.

The following example shows how to use MicrometerClientStatsReporter to define the metrics scope and set it with the WorkflowServiceStubsOptions.

//...
   // see the Micrometer documentation for configuration details on other supported monitoring systems.
   // in this example shows how to set up Prometheus registry and stats reported.
   PrometheusMeterRegistry registry = new PrometheusMeterRegistry(PrometheusConfig.DEFAULT);
   StatsReporter reporter = new MicrometerClientStatsReporter(registry);
    // set up a new scope, report every 10 seconds
     Scope scope = new RootScopeBuilder()
             .reporter(reporter)
             .reportEvery(com.uber.m3.util.Duration.ofSeconds(10));
   // for Prometheus collection, expose a scrape endpoint.
   //...
   // add metrics scope to WorkflowServiceStub options
   WorkflowServiceStubsOptions stubOptions =
       WorkflowServiceStubsOptions.newBuilder().setMetricsScope(scope).build();
//...

For more details, see the Java SDK Samples. For details on configuring a Prometheus scrape endpoint with Micrometer, see https://micrometer.io/docs/registry/prometheus#_configuring.