Prometheues metrics for APEX engine stats

Issue-ID: POLICY-3846
Signed-off-by: Rashmi Pujar <rashmi.pujar1@bell.ca>
Change-Id: I385446683372548f3fed6d609a9e85633ec2916d

2 files changed, 82 insertions, 9 deletions

diff --git a/core/core-engine/src/main/java/org/onap/policy/apex/core/engine/engine/impl/ApexEngineImpl.java b/core/core-engine/src/main/java/org/onap/policy/apex/core/engine/engine/impl/ApexEngineImpl.java
index 0d9d34d39..7bd9087df 100644
--- a/core/core-engine/src/main/java/org/onap/policy/apex/core/engine/engine/impl/ApexEngineImpl.java
+++ b/core/core-engine/src/main/java/org/onap/policy/apex/core/engine/engine/impl/ApexEngineImpl.java
@@ -2,7 +2,7 @@
  * ============LICENSE_START=======================================================
  *  Copyright (C) 2016-2018 Ericsson. All rights reserved.
  *  Modifications Copyright (C) 2019-2020 Nordix Foundation.
- *  Modifications Copyright (C) 2021 Bell Canada. All rights reserved.
+ *  Modifications Copyright (C) 2021-2022 Bell Canada. All rights reserved.
  *  Modifications Copyright (C) 2021 AT&T Intellectual Property. All rights reserved.
  * ================================================================================
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -25,6 +25,7 @@ package org.onap.policy.apex.core.engine.engine.impl;
 
 import static org.onap.policy.common.utils.validation.Assertions.argumentNotNull;
 
+import io.prometheus.client.Gauge;
 import java.util.Collection;
 import java.util.LinkedHashMap;
 import java.util.Map;
@@ -72,6 +73,11 @@ public class ApexEngineImpl implements ApexEngine {
     // Logger for this class
     private static final XLogger LOGGER = XLoggerFactory.getXLogger(ApexEngineImpl.class);
 
+    // Register state changes with prometheus
+    static final Gauge ENGINE_STATE = Gauge.build().name("apex_engine_state").labelNames("engine_instance_id")
+            .help("State of the APEX engine as integers mapped as - 0:UNDEFINED, 1:STOPPED, 2:READY,"
+                    + " 3:EXECUTING, 4:STOPPING").register();
+
     // Recurring string constants
     private static final String UPDATE_MODEL = "updateModel()<-";
     private static final String START = "start()<-";
@@ -123,6 +129,7 @@ public class ApexEngineImpl implements ApexEngine {
      */
     @Override
     public void updateModel(final AxPolicyModel apexModel, final boolean isSubsequentInstance) throws ApexException {
+        updateStatePrometheusMetric();
         if (apexModel != null) {
             LOGGER.entry("updateModel()->{}, apexPolicyModel {}", key.getId(), apexModel.getKey().getId());
         } else {
@@ -249,6 +256,7 @@ public class ApexEngineImpl implements ApexEngine {
 
         // OK, we are good to go
         state = AxEngineState.READY;
+        updateStatePrometheusMetric();
 
         LOGGER.exit("start()" + key);
     }
@@ -278,6 +286,7 @@ public class ApexEngineImpl implements ApexEngine {
                     case READY:
                     case STOPPED:
                         state = AxEngineState.STOPPED;
+                        updateStatePrometheusMetric();
                         stateMachineHandler.stop();
                         engineStats.engineStop();
                         LOGGER.exit("stop()" + key);
@@ -286,6 +295,7 @@ public class ApexEngineImpl implements ApexEngine {
                     // Engine is executing a policy, wait for it to stop
                     case EXECUTING:
                         state = AxEngineState.STOPPING;
+                        updateStatePrometheusMetric();
                         break;
 
                     // Wait for the engine to stop
@@ -303,6 +313,7 @@ public class ApexEngineImpl implements ApexEngine {
         synchronized (stateLockObj) {
             state = AxEngineState.STOPPED;
         }
+        updateStatePrometheusMetric();
 
         throw new ApexException(STOP + key.getId() + "," + state + ", error stopping engine, engine stop timed out");
     }
@@ -370,6 +381,7 @@ public class ApexEngineImpl implements ApexEngine {
 
             state = AxEngineState.EXECUTING;
         }
+        updateStatePrometheusMetric();
 
         String message = "execute(): triggered by event " + incomingEvent.toString();
         LOGGER.debug(message);
@@ -413,6 +425,7 @@ public class ApexEngineImpl implements ApexEngine {
                 state = AxEngineState.STOPPED;
             }
         }
+        updateStatePrometheusMetric();
         return ret;
     }
 
@@ -507,4 +520,11 @@ public class ApexEngineImpl implements ApexEngine {
 
         return Set.of(exceptionEvent);
     }
-}
+
+    /**
+     * Update the APEX engine state to prometheus for monitoring.
+     */
+    private void updateStatePrometheusMetric() {
+        ENGINE_STATE.labels(getKey().getId()).set(state.getStateIdentifier());
+    }
+}
\ No newline at end of file
diff --git a/core/core-engine/src/test/java/org/onap/policy/apex/core/engine/engine/impl/ApexEngineImplTest.java b/core/core-engine/src/test/java/org/onap/policy/apex/core/engine/engine/impl/ApexEngineImplTest.java
index c9d9b9c8d..88602206d 100644
--- a/core/core-engine/src/test/java/org/onap/policy/apex/core/engine/engine/impl/ApexEngineImplTest.java
+++ b/core/core-engine/src/test/java/org/onap/policy/apex/core/engine/engine/impl/ApexEngineImplTest.java
@@ -30,6 +30,7 @@ import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 
+import io.prometheus.client.CollectorRegistry;
 import java.io.IOException;
 import java.lang.reflect.Field;
 import java.util.HashMap;
@@ -70,6 +71,8 @@ import org.onap.policy.common.parameters.ParameterService;
  * Test the engine implementation.
  */
 public class ApexEngineImplTest {
+    private static final String ENGINE_ID = "Engine:0.0.1";
+
     private AxPolicyModel policyModel;
     private AxPolicyModel incompatiblePolicyModel;
     private AxPolicyModel policyModelWithStates;
@@ -170,7 +173,7 @@ public class ApexEngineImplTest {
 
     @Test
     public void testSanity() throws ApexException  {
-        AxArtifactKey engineKey = new AxArtifactKey("Engine:0.0.1");
+        AxArtifactKey engineKey = new AxArtifactKey(ENGINE_ID);
         ApexEngineImpl engine = (ApexEngineImpl) new ApexEngineFactory().createApexEngine(engineKey);
         assertNotNull(engine);
         assertEquals(engineKey, engine.getKey());
@@ -182,6 +185,7 @@ public class ApexEngineImplTest {
             .hasMessage("stop()<-Engine:0.0.1,STOPPED, cannot stop engine, " + "engine is already stopped");
 
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
         assertEquals(0, engine.getEngineContext().size());
         assertEquals(engineKey, engine.getEngineStatus().getKey());
         assertNull(engine.getInternalContext());
@@ -200,7 +204,7 @@ public class ApexEngineImplTest {
 
     @Test
     public void testListener() throws ApexException {
-        AxArtifactKey engineKey = new AxArtifactKey("Engine:0.0.1");
+        AxArtifactKey engineKey = new AxArtifactKey(ENGINE_ID);
         ApexEngineImpl engine = (ApexEngineImpl) new ApexEngineFactory().createApexEngine(engineKey);
 
         engine.addEventListener("myListener", new DummyListener());
@@ -227,6 +231,7 @@ public class ApexEngineImplTest {
 
         engine.start();
         assertEquals(AxEngineState.READY, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.READY);
 
         assertThatThrownBy(engine::start)
             .hasMessage("start()<-Engine:0.0.1,READY, cannot start engine, engine not in state STOPPED");
@@ -236,25 +241,29 @@ public class ApexEngineImplTest {
 
         engine.stop();
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
 
         engine.clear();
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
 
         assertThatThrownBy(engine::start).hasMessage("start()<-Engine:0.0.1,STOPPED,  cannot start engine, "
             + "engine has not been initialized, its model is not loaded");
 
         engine.updateModel(policyModel, false);
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
 
         engine.start();
         assertEquals(AxEngineState.READY, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.READY);
 
         assertNull(engine.createEvent(null));
     }
 
     @Test
     public void testEventKey() throws ApexException {
-        AxArtifactKey engineKey = new AxArtifactKey("Engine:0.0.1");
+        AxArtifactKey engineKey = new AxArtifactKey(ENGINE_ID);
         ApexEngineImpl engine = (ApexEngineImpl) new ApexEngineFactory().createApexEngine(engineKey);
         engine.updateModel(policyModel, false);
         engine.start();
@@ -265,33 +274,41 @@ public class ApexEngineImplTest {
 
         assertTrue(engine.handleEvent(event));
         assertEquals(AxEngineState.READY, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.READY);
 
         engine.stop();
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
 
         engine.addEventListener("myListener", new DummyListener());
 
         engine.start();
         assertEquals(AxEngineState.READY, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.READY);
 
         assertThatThrownBy(() -> engine.updateModel(policyModel, false)).hasMessage(
             "updateModel()<-Engine:0.0.1, cannot update model, engine should be stopped but is in state READY");
 
         assertTrue(engine.handleEvent(event));
         assertEquals(AxEngineState.READY, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.READY);
 
         engine.stop();
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
 
         engine.addEventListener("badListener", new DummyEnEventListener());
 
         engine.start();
         assertEquals(AxEngineState.READY, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.READY);
 
         assertFalse(engine.handleEvent(event));
         assertEquals(AxEngineState.READY, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.READY);
         engine.stop();
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
 
         engine.removeEventListener("badListener");
         engine.addEventListener("slowListener", new DummySlowEnEventListener());
@@ -299,21 +316,24 @@ public class ApexEngineImplTest {
 
     @Test
     public void testState() throws InterruptedException, ApexException {
-        AxArtifactKey engineKey = new AxArtifactKey("Engine:0.0.1");
+        AxArtifactKey engineKey = new AxArtifactKey(ENGINE_ID);
         ApexEngineImpl engine = (ApexEngineImpl) new ApexEngineFactory().createApexEngine(engineKey);
         assertNotNull(engine);
         assertEquals(engineKey, engine.getKey());
 
         engine.updateModel(policyModel, false);
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
 
         DummySlowEnEventListener slowListener = new DummySlowEnEventListener();
         engine.addEventListener("slowListener", slowListener);
 
         engine.start();
         assertEquals(AxEngineState.READY, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.READY);
 
         assertEquals(AxEngineState.READY, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.READY);
 
         AxArtifactKey eventKey = new AxArtifactKey("Event:0.0.1");
         EnEvent event = engine.createEvent(eventKey);
@@ -329,15 +349,18 @@ public class ApexEngineImplTest {
         }).start();
         await().atLeast(50, TimeUnit.MILLISECONDS).until(() -> engine.getState().equals(AxEngineState.EXECUTING));
         assertEquals(AxEngineState.EXECUTING, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.EXECUTING);
 
         assertFalse(engine.handleEvent(event));
         assertNotNull(engine.createEvent(eventKey));
 
         engine.stop();
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
 
         engine.start();
         assertEquals(AxEngineState.READY, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.READY);
 
         // 4 seconds is more than the 3 second wait on engine stopping
         slowListener.setWaitTime(4000);
@@ -350,24 +373,28 @@ public class ApexEngineImplTest {
 
         await().atLeast(50, TimeUnit.MILLISECONDS).until(() -> engine.getState().equals(AxEngineState.EXECUTING));
         assertEquals(AxEngineState.EXECUTING, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.EXECUTING);
         assertThatThrownBy(engine::stop)
             .hasMessage("stop()<-Engine:0.0.1,STOPPED, error stopping engine, engine stop timed out");
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
         engine.clear();
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
     }
 
     @Test
     public void testStateMachineError() throws InterruptedException, IllegalArgumentException, IllegalAccessException,
                     NoSuchFieldException, SecurityException, ApexException {
 
-        AxArtifactKey engineKey = new AxArtifactKey("Engine:0.0.1");
+        AxArtifactKey engineKey = new AxArtifactKey(ENGINE_ID);
         ApexEngineImpl engine = (ApexEngineImpl) new ApexEngineFactory().createApexEngine(engineKey);
         assertNotNull(engine);
         assertEquals(engineKey, engine.getKey());
 
         engine.updateModel(policyModel, false);
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
 
         final Field smHandlerField = engine.getClass().getDeclaredField("stateMachineHandler");
         smHandlerField.setAccessible(true);
@@ -375,8 +402,10 @@ public class ApexEngineImplTest {
 
         engine.start();
         assertEquals(AxEngineState.READY, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.READY);
 
         assertEquals(AxEngineState.READY, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.READY);
 
         AxArtifactKey eventKey = new AxArtifactKey("Event:0.0.1");
         EnEvent event = engine.createEvent(eventKey);
@@ -384,32 +413,38 @@ public class ApexEngineImplTest {
 
         assertFalse(engine.handleEvent(event));
         assertEquals(AxEngineState.READY, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.READY);
 
         engine.stop();
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
         Mockito.doThrow(new StateMachineException("mocked state machine exception",
                 new IOException("nexted exception"))).when(smHandlerMock).start();
         assertThatThrownBy(engine::start).hasMessage("updateModel()<-Engine:0.0.1, error starting the engine state "
                 + "machines \"Engine:0.0.1\"");
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
 
         engine.clear();
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
     }
 
     @Test
     public void testStateMachineHandler() throws InterruptedException, IllegalArgumentException, IllegalAccessException,
                     NoSuchFieldException, SecurityException, ApexException {
-        AxArtifactKey engineKey = new AxArtifactKey("Engine:0.0.1");
+        AxArtifactKey engineKey = new AxArtifactKey(ENGINE_ID);
         ApexEngineImpl engine = (ApexEngineImpl) new ApexEngineFactory().createApexEngine(engineKey);
         assertNotNull(engine);
         assertEquals(engineKey, engine.getKey());
 
         engine.updateModel(policyModelWithStates, false);
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
 
         engine.start();
         assertEquals(AxEngineState.READY, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.READY);
 
         AxArtifactKey eventKey = new AxArtifactKey("Event:0.0.1");
         EnEvent event = engine.createEvent(eventKey);
@@ -417,17 +452,22 @@ public class ApexEngineImplTest {
 
         engine.stop();
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
 
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
 
         engine.start();
         assertEquals(AxEngineState.READY, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.READY);
 
         assertEquals(AxEngineState.READY, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.READY);
 
         // Can't work, state is not fully defined
         assertFalse(engine.handleEvent(event));
         assertEquals(AxEngineState.READY, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.READY);
 
         final Field smHandlerField = engine.getClass().getDeclaredField("stateMachineHandler");
         smHandlerField.setAccessible(true);
@@ -448,22 +488,35 @@ public class ApexEngineImplTest {
 
         engine.stop();
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
 
         assertThatThrownBy(engine::start).hasMessageContaining("updateModel()<-Engine:0.0.1, error starting the "
                     + "engine state machines \"Engine:0.0.1\"");
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
 
         engine.start();
         assertEquals(AxEngineState.READY, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.READY);
 
         // Works, Dummy executor fakes event execution
         assertTrue(engine.handleEvent(event));
         assertEquals(AxEngineState.READY, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.READY);
 
         engine.stop();
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
 
         engine.clear();
         assertEquals(AxEngineState.STOPPED, engine.getState());
+        checkAxEngineStateMetric(AxEngineState.STOPPED);
+    }
+
+    private void checkAxEngineStateMetric(AxEngineState state) {
+        Double stateMetric = CollectorRegistry.defaultRegistry
+                .getSampleValue("apex_engine_state", new String[]{"engine_instance_id"},
+                        new String[]{ENGINE_ID});
+        assertEquals(stateMetric.intValue(), state.getStateIdentifier());
     }
-}
+}
\ No newline at end of file