Added list_jvms option to list available JVMs (that this process can …

…see)

src/main/java/org/datadog/jmxfetch/App.java

@@ -25,6 +25,7 @@
 import com.beust.jcommander.JCommander;
 import com.beust.jcommander.ParameterException;
 
+
 @SuppressWarnings("unchecked")
 public class App {
     private final static Logger LOGGER = Logger.getLogger(App.class.getName());
@@ -81,6 +82,15 @@ public static void main(String[] args) {
             System.exit(1);
         }
 
+        if( config.getAction().equals( AppConfig.ACTION_LIST_JVMS )) {
+            List<com.sun.tools.attach.VirtualMachineDescriptor> descriptors = com.sun.tools.attach.VirtualMachine.list();
+            System.out.println("List of JVMs for user " + System.getProperty("user.name") );
+            for( com.sun.tools.attach.VirtualMachineDescriptor descriptor : descriptors ) {
+                System.out.println( "\tJVM id " + descriptor.id() + ": '" + descriptor.displayName() + "'" );
+            }
+            System.exit(0);
+        }
+
         // Set up the shutdown hook to properly close resources
         attachShutdownHook();
 
@@ -320,8 +330,10 @@ public void init(boolean forceNewConnection) {
         clearInstances(instances);
         clearInstances(brokenInstances);
 
+
         Reporter reporter = appConfig.getReporter();
 
+
         Iterator<Entry<String, YamlParser>> it = configs.entrySet().iterator();
         while (it.hasNext()) {
             Map.Entry<String, YamlParser> entry = it.next();

src/main/java/org/datadog/jmxfetch/AppConfig.java

@@ -18,14 +18,15 @@
 @Parameters(separators = "=")
 class AppConfig {
     public static final String ACTION_COLLECT = "collect";
+    public static final String ACTION_LIST_JVMS = "list_jvms";
     public static final String ACTION_LIST_EVERYTHING = "list_everything";
     public static final String ACTION_LIST_COLLECTED = "list_collected_attributes";
     public static final String ACTION_LIST_MATCHING = "list_matching_attributes";
     public static final String ACTION_LIST_NOT_MATCHING = "list_not_matching_attributes";
     public static final String ACTION_LIST_LIMITED = "list_limited_attributes";
     public static final String ACTION_HELP = "help";
     public static final HashSet<String> ACTIONS = new HashSet<String>(Arrays.asList(ACTION_COLLECT, ACTION_LIST_EVERYTHING,
-            ACTION_LIST_COLLECTED, ACTION_LIST_MATCHING, ACTION_LIST_NOT_MATCHING, ACTION_LIST_LIMITED, ACTION_HELP));
+            ACTION_LIST_COLLECTED, ACTION_LIST_MATCHING, ACTION_LIST_NOT_MATCHING, ACTION_LIST_LIMITED, ACTION_HELP, ACTION_LIST_JVMS));
 
     @Parameter(names = {"--help", "-h"},
             description = "Display this help page",
@@ -81,7 +82,7 @@ class AppConfig {
 
     @Parameter(description = "Action to take, should be in [help, collect, " +
             "list_everything, list_collected_attributes, list_matching_attributes, " +
-            "list_not_matching_attributes, list_limited_attributes]",
+            "list_not_matching_attributes, list_limited_attributes, list_jvms]",
             required = true)
     private List<String> action = null;
 

src/main/java/org/datadog/jmxfetch/AttachApiConnection.java

@@ -2,8 +2,10 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.LinkedHashMap;
+import java.util.List;
 
 import javax.management.remote.JMXServiceURL;
 
@@ -29,13 +31,15 @@ private JMXServiceURL getAddress(LinkedHashMap<String, Object> connectionParams)
             throw new IOException("Unnable to attach to process regex:  "+ processRegex, e);
         }
         return address;
-        
+
     }
 
      private String getJMXUrlForProcessRegex(String processRegex) throws com.sun.tools.attach.AttachNotSupportedException, IOException {
+         List<String> jvms = new ArrayList<String>();
         for (com.sun.tools.attach.VirtualMachineDescriptor vmd : com.sun.tools.attach.VirtualMachine.list()) {
             if (vmd.displayName().matches(processRegex)) {
                 com.sun.tools.attach.VirtualMachine vm = com.sun.tools.attach.VirtualMachine.attach(vmd);
+                LOGGER.info("Matched JVM '" + vmd.displayName() + "' against regex '" + processRegex + "'");
                 String connectorAddress = vm.getAgentProperties().getProperty(CONNECTOR_ADDRESS);
                 //If jmx agent is not running in VM, load it and return the connector url
                 if (connectorAddress == null) {
@@ -48,8 +52,10 @@ private String getJMXUrlForProcessRegex(String processRegex) throws com.sun.tool
 
                 return connectorAddress;
             }
+            jvms.add( vmd.displayName() );
         }
-        throw new IOException("Cannot find JVM matching regex: " + processRegex);
+
+        throw new IOException("Cannot find JVM matching regex: '" + processRegex + "'; available JVMs (for this user account): " + jvms );
     }
 
     private void loadJMXAgent(com.sun.tools.attach.VirtualMachine vm) throws IOException {

src/test/java/org/datadog/jmxfetch/TestParsingJCommander.java

@@ -312,7 +312,7 @@ public void testParsingAction() {
         } catch (ParameterException pe) {
             String expectedMessage = "Main parameters are required (\"Action to take, should be in [help, collect, " +
                     "list_everything, list_collected_attributes, list_matching_attributes, " +
-                    "list_not_matching_attributes, list_limited_attributes]\")";
+                    "list_not_matching_attributes, list_limited_attributes, list_jvms]\")";
             assertEquals(expectedMessage, pe.getMessage());
         }
 
@@ -329,7 +329,7 @@ public void testParsingAction() {
         } catch (ParameterException pe) {
             String expectedMessage = "Main parameters are required (\"Action to take, should be in [help, collect, " +
                     "list_everything, list_collected_attributes, list_matching_attributes, " +
-                    "list_not_matching_attributes, list_limited_attributes]\")";
+                    "list_not_matching_attributes, list_limited_attributes, list_jvms]\")";
             assertEquals(expectedMessage, pe.getMessage());
         }
     }

src/test/java/org/datadog/jmxfetch/TestServiceChecks.java

@@ -113,7 +113,7 @@ public void testServiceCheckCRITICAL() throws Exception {
 
         assertEquals(Reporter.formatServiceCheckPrefix("non_running_process"), scName);
         assertEquals(Status.STATUS_ERROR, scStatus);
-        assertEquals("Cannot connect to instance process_regex: .*non_running_process_test.* Cannot find JVM matching regex: .*non_running_process_test.*", scMessage);
+        assertTrue( scMessage, scMessage.startsWith("Cannot connect to instance process_regex: .*non_running_process_test.* Cannot find JVM matching regex: '.*non_running_process_test.*'; available JVMs (for this user account): "));
         assertEquals(scTags.length, 3);
         assertTrue(Arrays.asList(scTags).contains("instance:jmx_test_instance"));