Prom.java

@Path("/prometheus")
public class SimplePrometheusEndpoint {

    {
        // Initialize the default metrics for the hotspot VM
        DefaultExports.initialize();
    }


    @GET
    @Path("/metrics")
    @Produces(MediaType.TEXT_PLAIN)
    public StreamingOutput metrics() {

        return output -> {
            try (final Writer writer = new OutputStreamWriter(output)) {
                TextFormat.write004(writer, CollectorRegistry.defaultRegistry.metricFamilySamples());
            }
        };
    }

}