add metrics example (#578)

* add metrics example

* correct for metrics in arguments

Author: jackshirazi

examples/troubleshooting/README.md

@@ -16,26 +16,36 @@ dependencies will allow for easy compilation
 
 (Manual compilation would require the jars and their dependencies downloaded, and then javac -cp <list of jars> path-to-java-file.)
 
-# Traces
+# Traces, Metrics, Logs
 
-The [`TestOtelSdkTrace`](./src/main/java/elastic/troubleshooting/TestOtelSdkTrace.java) class is a standalone class that creates
-a span (named `test span`) in a service that you name. It takes
-three arguments
+The examples in this section all take the same three arguments:
 1. The name of the service you want to have displayed in the APM UI
 2. The endpoint to send traces to, normally the Elastic APM server or the OpenTelemetry collector.
-   The url would typically look like `http://localhost:4318/v1/traces` or `https://somewhere:443/v1/traces` 
-   but if `/v1/traces` is missing from the argument, it is added to the endpoint 
-3. The secret token or apikey in the format secret:<token> or apikey:<apikey>. 
-   If the argument doesn't start with neither `secret:` nor `apikey:`, then the full argument is assumed to be a secret token
+   The url would typically look like `http://localhost:4318/v1/traces` or `https://somewhere:443/v1/traces`
+   but if `/v1/traces` is missing from the argument, it is added to the endpoint
+   - for metrics, replace `/traces` with `/metrics` in the above paths
+3. The secret token or apikey in the format secret:<token> or apikey:<apikey>.
+   If the argument doesn't start with neither `secret:` nor `apikey:`, then the full argument is
+   assumed to be a secret token
+
+## Traces
+
+The [`TestOtelSdkTrace`](./src/main/java/elastic/troubleshooting/TestOtelSdkTrace.java) class is a standalone class that creates
+a span (named `test span`) in a service that you name. 
 
 After running the class, you should see the trace in the APM UI, eg with service name set to `test1` and
 correct endpoint and token, you should see something similar to 
 ![this](images\test-trace.png)
 
-# Metrics
+## Metrics
 
-To do
+The [`TestOtelSdkMetrics`](./src/main/java/elastic/troubleshooting/TestOtelSdkMetrics.java) class is a standalone class that generates
+metrics for `jvm.thread.count` for a little over 3 minutes in a service that you name.
+
+After running the class, you should see the metrics in the APM UI, eg with service name set to `test1` and
+correct endpoint and token, you should see something similar to
+![this](images\test-metrics.png)
 
-# Logs
+## Logs
 
 To do

examples/troubleshooting/images/test-metrics.png

@@ -0,0 +1,72 @@
+package elastic.troubleshooting;
+
+import java.util.concurrent.TimeUnit;
+
+import io.opentelemetry.api.metrics.LongCounter;
+import io.opentelemetry.api.metrics.Meter;
+import io.opentelemetry.exporter.otlp.http.metrics.OtlpHttpMetricExporter;
+import io.opentelemetry.sdk.OpenTelemetrySdk;
+import io.opentelemetry.sdk.metrics.SdkMeterProvider;
+import io.opentelemetry.sdk.metrics.export.MetricReader;
+import io.opentelemetry.sdk.metrics.export.PeriodicMetricReader;
+import io.opentelemetry.sdk.resources.Resource;
+
+public class TestOtelSdkMetrics {
+
+  public static void main(String[] args) throws Exception {
+    String servicename = args[0];
+    String endpoint = args[1];
+    String secretOrApikey = args[2];
+    if (!endpoint.endsWith("/v1/metrics")) {
+      if (endpoint.endsWith("/")) {
+        endpoint = endpoint + "v1/metrics";
+      } else {
+        endpoint = endpoint + "/v1/metrics";
+      }
+    }
+    boolean isSecret = true;
+    if (secretOrApikey.startsWith("secret:")) {
+      secretOrApikey = secretOrApikey.substring(7);
+    } else if (secretOrApikey.startsWith("apikey:")) {
+      secretOrApikey = secretOrApikey.substring(7);
+      isSecret = false;
+    }
+
+    System.out.println("Starting test ... initializing OpenTelemetry");
+
+    Resource resource = Resource.getDefault().toBuilder().put("service.name", servicename).build();
+
+    OtlpHttpMetricExporter metricExporter = OtlpHttpMetricExporter.builder().setEndpoint(endpoint)
+        .addHeader("Authorization", (isSecret ? "Bearer " : "ApiKey ") + secretOrApikey).build();
+
+    MetricReader metricReader = PeriodicMetricReader.builder(metricExporter)
+        .setInterval(3, TimeUnit.SECONDS)
+        .build();
+
+    SdkMeterProvider meterProvider = SdkMeterProvider.builder().registerMetricReader(metricReader)
+        .setResource(resource).build();
+
+    OpenTelemetrySdk openTelemetry = OpenTelemetrySdk.builder().setMeterProvider(meterProvider)
+        .build();
+
+    System.out.println("Starting test ... creating metrics");
+
+    Meter meter = openTelemetry.getMeter("TestOtelSdktrace");
+    LongCounter counter = meter.counterBuilder("jvm.thread.count").build();
+    for (int i = 0; i < 100; i++) {
+      counter.add(3);
+      Thread.sleep(1000L);
+    }
+    for (int i = 0; i < 100; i++) {
+      counter.add(0);
+      Thread.sleep(1000L);
+    }
+
+    openTelemetry.shutdown().whenComplete(() -> {
+      System.out.println("Ending test ... shutdown OpenTelemetry");
+    });
+
+    Thread.sleep(60_000L);
+    System.out.println("Ending test ... terminating the JVM");
+  }
+}