Integrating prometheus with Policy components

With this change, all PF components can export prometheus metrics
by default. The prometheus metrics servlet will be running on
/metrics servletPath..
If the metrics shouldn't be exported, just add a flag
    "promethus": false
in the restServerParameters of default configuration file.
This brings up prometheus servlet on /metrics servletPath.

Also as part of standard servlet support, "servletUriPath" and
"servletClass" are 2 other fields added to RestServerParameters
which can be used to add standard servlets. This can be revisited later
if needed.
Basically, any servlet can be added by passing these fields, for
example, to add prometheus metrics servlet on /test/metrics,
add the below to restServerParameters:
    "servletUriPath": "/test/metrics",
    "servletClass": "io.prometheus.client.exporter.MetricsServlet"

In addition, we can later go to individual components and add more
metrics, say for e.g.,
deployedPoliciesCounter/undeployedPoliciesCounter etc on PAP,
executedEvents/failedEvents etc on PDP and so on.
This will look something like below, for e.g. in policy-pap component:
 io.prometheus.client.Counter counter = Counter.build()
  .name("policies_deployed_total")
  .help("Number of policies deployed.").register()
Whenever a policy is deployed, just call
 counter.inc()

Usage of code like above in the individual component will expose
such data as well as part of the exposed metrics.

Change-Id: Id667f27b15c012398421ba657b5324cc1d82cf1f
Issue-ID: POLICY-3524
Signed-off-by: a.sreekumar <ajith.sreekumar@bell.ca>
Signed-off-by: jhh <jorge.hernandez-herrero@att.com>
Signed-off-by: a.sreekumar <ajith.sreekumar@bell.ca>

1 files changed, 37 insertions, 0 deletions

diff --git a/policy-endpoints/src/test/java/org/onap/policy/common/endpoints/http/server/test/RestServerTest.java b/policy-endpoints/src/test/java/org/onap/policy/common/endpoints/http/server/test/RestServerTest.java
index 16f17652..65af469b 100644
--- a/policy-endpoints/src/test/java/org/onap/policy/common/endpoints/http/server/test/RestServerTest.java
+++ b/policy-endpoints/src/test/java/org/onap/policy/common/endpoints/http/server/test/RestServerTest.java
@@ -3,6 +3,7 @@
  * ONAP
  * ================================================================================
  * Copyright (C) 2019-2020 AT&T Intellectual Property. All rights reserved.
+ * Modifications Copyright (C) 2021 Bell Canada. All rights reserved.
  * ================================================================================
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -31,6 +32,7 @@ import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
+import io.prometheus.client.exporter.MetricsServlet;
 import java.io.IOException;
 import java.io.PrintWriter;
 import java.net.HttpURLConnection;
@@ -69,6 +71,7 @@ import org.onap.policy.common.utils.network.NetworkUtil;
 import org.powermock.reflect.Whitebox;
 
 public class RestServerTest {
+    private static final String METRICS_URI = "/metrics";
     private static final String SERVER1 = "my-server-A";
     private static final String SERVER2 = "my-server-B";
     private static final String FACTORY_FIELD = "factory";
@@ -231,6 +234,40 @@ public class RestServerTest {
         assertEquals(String.join(",", GsonMessageBodyHandler.class.getName(), YamlMessageBodyHandler.class.getName(),
                         JsonExceptionMapper.class.getName(), YamlExceptionMapper.class.getName()),
                         props.getProperty(svcpfx + PolicyEndPointProperties.PROPERTY_HTTP_SERIALIZATION_PROVIDER));
+        assertEquals("false", props.getProperty(svcpfx + PolicyEndPointProperties.PROPERTY_HTTP_PROMETHEUS_SUFFIX));
+    }
+
+    @Test
+    public void testExplicitPrometheusAddedToProperty() {
+        when(params.isPrometheus()).thenReturn(true);
+        rest = new RestServer(params, Filter.class, Provider1.class, Provider2.class);
+        ArgumentCaptor<Properties> cap = ArgumentCaptor.forClass(Properties.class);
+        verify(serverFactory).build(cap.capture());
+
+        Properties props = cap.getValue();
+        String svcpfx = PolicyEndPointProperties.PROPERTY_HTTP_SERVER_SERVICES + "." + PARAM_NAME;
+
+        assertEquals("true", props.getProperty(svcpfx + PolicyEndPointProperties.PROPERTY_HTTP_PROMETHEUS_SUFFIX));
+        assertThat(props.getProperty(svcpfx + PolicyEndPointProperties.PROPERTY_HTTP_SERVLET_URIPATH_SUFFIX)).isBlank();
+        assertThat(props.getProperty(svcpfx + PolicyEndPointProperties.PROPERTY_HTTP_SERVLET_CLASS_SUFFIX)).isBlank();
+    }
+
+    @Test
+    public void testStandardSevletAddedToProperty() {
+        when(params.getServletUriPath()).thenReturn("/metrics");
+        when(params.getServletClass()).thenReturn(MetricsServlet.class.getName());
+        rest = new RestServer(params, Filter.class, Provider1.class, Provider2.class);
+        ArgumentCaptor<Properties> cap = ArgumentCaptor.forClass(Properties.class);
+        verify(serverFactory).build(cap.capture());
+
+        Properties props = cap.getValue();
+        String svcpfx = PolicyEndPointProperties.PROPERTY_HTTP_SERVER_SERVICES + "." + PARAM_NAME;
+
+        assertEquals("false", props.getProperty(svcpfx + PolicyEndPointProperties.PROPERTY_HTTP_PROMETHEUS_SUFFIX));
+        assertEquals(METRICS_URI,
+            props.getProperty(svcpfx + PolicyEndPointProperties.PROPERTY_HTTP_SERVLET_URIPATH_SUFFIX));
+        assertEquals(MetricsServlet.class.getName(),
+            props.getProperty(svcpfx + PolicyEndPointProperties.PROPERTY_HTTP_SERVLET_CLASS_SUFFIX));
     }
 
     @Test