Add integration test for jmxfetch

dd-java-agent-ittests/src/test/groovy/datadog/trace/agent/JMXFetchTest.groovy

@@ -0,0 +1,52 @@
+package datadog.trace.agent
+
+import datadog.trace.agent.test.IntegrationTestUtils
+import datadog.trace.api.Config
+import org.junit.Rule
+import org.junit.contrib.java.lang.system.RestoreSystemProperties
+import spock.lang.Specification
+
+import java.lang.reflect.Method
+
+class JMXFetchTest extends Specification {
+
+  @Rule
+  public final RestoreSystemProperties restoreSystemProperties = new RestoreSystemProperties()
+
+  def "test jmxfetch"() {
+    setup:
+    def currentContextLoader = Thread.currentThread().getContextClassLoader()
+    DatagramSocket socket = new DatagramSocket(0)
+
+    System.properties.setProperty("dd.jmxfetch.enabled", "true")
+    System.properties.setProperty("dd.jmxfetch.statsd.port", Integer.toString(socket.localPort))
+    // Overwrite writer type to disable console jmxfetch reporter
+    System.properties.setProperty("dd.writer.type", "DDAgentWriter")
+
+    def classLoader = IntegrationTestUtils.getJmxFetchClassLoader()
+    // Have to set this so JMXFetch knows where to find resources
+    Thread.currentThread().setContextClassLoader(classLoader)
+    final Class<?> jmxFetchAgentClass =
+      classLoader.loadClass("datadog.trace.agent.jmxfetch.JMXFetch")
+    final Method jmxFetchInstallerMethod = jmxFetchAgentClass.getDeclaredMethod("run", Config)
+    jmxFetchInstallerMethod.setAccessible(true)
+    jmxFetchInstallerMethod.invoke(null, new Config())
+
+    byte[] buf = new byte[1500]
+    DatagramPacket packet = new DatagramPacket(buf, buf.length)
+    socket.receive(packet)
+    String received = new String(packet.getData(), 0, packet.getLength())
+
+    Set<String> threads = Thread.getAllStackTraces().keySet().collect { it.name }
+
+    expect:
+    threads.contains("dd-jmx-collector")
+    received.contains("jvm.")
+
+    cleanup:
+    jmxFetchInstallerMethod.setAccessible(false)
+    socket.close()
+    Thread.currentThread().setContextClassLoader(currentContextLoader)
+  }
+
+}

dd-java-agent-ittests/src/test/java/datadog/trace/agent/test/IntegrationTestUtils.java

@@ -32,31 +32,21 @@ public class IntegrationTestUtils {
 
   /** Returns the classloader the core agent is running on. */
   public static ClassLoader getAgentClassLoader() {
-    Field classloaderField = null;
-    try {
-      Class<?> tracingAgentClass =
-          tracingAgentClass =
-              ClassLoader.getSystemClassLoader().loadClass("datadog.trace.agent.TracingAgent");
-      classloaderField = tracingAgentClass.getDeclaredField("AGENT_CLASSLOADER");
-      classloaderField.setAccessible(true);
-      return (ClassLoader) classloaderField.get(null);
-    } catch (final Exception e) {
-      throw new IllegalStateException(e);
-    } finally {
-      if (null != classloaderField) {
-        classloaderField.setAccessible(false);
-      }
-    }
+    return getTracingAgentFieldClassloader("AGENT_CLASSLOADER");
   }
 
   /** Returns the classloader the jmxfetch is running on. */
   public static ClassLoader getJmxFetchClassLoader() {
+    return getTracingAgentFieldClassloader("JMXFETCH_CLASSLOADER");
+  }
+
+  private static ClassLoader getTracingAgentFieldClassloader(final String fieldName) {
     Field classloaderField = null;
     try {
       Class<?> tracingAgentClass =
           tracingAgentClass =
               ClassLoader.getSystemClassLoader().loadClass("datadog.trace.agent.TracingAgent");
-      classloaderField = tracingAgentClass.getDeclaredField("JMXFETCH_CLASSLOADER");
+      classloaderField = tracingAgentClass.getDeclaredField(fieldName);
       classloaderField.setAccessible(true);
       return (ClassLoader) classloaderField.get(null);
     } catch (final Exception e) {

dd-java-agent/agent-jmxfetch/src/main/java/datadog/trace/agent/jmxfetch/JMXFetch.java

@@ -16,16 +16,20 @@ public class JMXFetch {
   private static final int SLEEP_AFTER_JMXFETCH_EXITS = 5000;
 
   public static final void run() {
+    run(Config.get());
+  }
 
-    if (!Config.get().isJmxFetchEnabled()) {
+  // This is used by tests
+  private static void run(final Config config) {
+    if (!config.isJmxFetchEnabled()) {
       log.info("JMXFetch is disabled");
       return;
     }
 
-    final List<String> metricsConfigs = Config.get().getJmxFetchMetricsConfigs();
-    final Integer checkPeriod = Config.get().getJmxFetchCheckPeriod();
-    final Integer refreshBeansPeriod = Config.get().getJmxFetchRefreshBeansPeriod();
-    final String reporter = getReporter();
+    final List<String> metricsConfigs = config.getJmxFetchMetricsConfigs();
+    final Integer checkPeriod = config.getJmxFetchCheckPeriod();
+    final Integer refreshBeansPeriod = config.getJmxFetchRefreshBeansPeriod();
+    final String reporter = getReporter(config);
     final String logLocation = getLogLocation();
     final String logLevel = getLogLevel();
 
@@ -37,7 +41,7 @@ public class JMXFetch {
         reporter,
         logLocation,
         logLevel);
-    final AppConfig config =
+    final AppConfig appConfig =
         AppConfig.create(
             DEFAULT_CONFIGS,
             metricsConfigs,
@@ -54,7 +58,7 @@ public class JMXFetch {
               public void run() {
                 while (true) {
                   try {
-                    final int result = App.run(config);
+                    final int result = App.run(appConfig);
                     log.error("jmx collector exited with result: " + result);
                   } catch (final Exception e) {
                     log.error("Exception in jmx collector thread", e);
@@ -74,8 +78,7 @@ public class JMXFetch {
     thread.start();
   }
 
-  private static String getReporter() {
-    final Config config = Config.get();
+  private static String getReporter(final Config config) {
     if (Config.LOGGING_WRITER_TYPE.equals(config.getWriterType())) {
       // If logging writer is enabled then also enable console reporter in JMXFetch
       return "console";