Feature/583 offline nodes metrics

src/main/java/org/jenkinsci/plugins/prometheus/collectors/CollectorType.java

@@ -6,6 +6,7 @@ public enum CollectorType {
     JENKINS_UPTIME_GAUGE("uptime"),
     JENKINS_VERSION_INFO_GAUGE("version"),
     NODES_ONLINE_GAUGE("nodes_online"),
+    NODES_OFFLINE_GAUGE("nodes_offline"),
     BUILD_DURATION_GAUGE("build_duration_milliseconds"),
     BUILD_DURATION_SUMMARY("duration_milliseconds_summary"),
     BUILD_FAILED_COUNTER("failed_build_count"),

src/main/java/org/jenkinsci/plugins/prometheus/collectors/jenkins/JenkinsCollectorFactory.java

@@ -22,10 +22,15 @@
             case JENKINS_UP_GAUGE:
                 return saveBuildCollector(new JenkinsUpGauge(labelNames, namespace, subsystem));
             case NODES_ONLINE_GAUGE:
-                if (!isNodeOnlineGaugeEnabled()) {
+                if (!isNodeStatusGaugeEnabled()) {
                     return new NoOpMetricCollector<>();
                 }
                 return saveBuildCollector(new NodesOnlineGauge(labelNames, namespace, subsystem));
+            case NODES_OFFLINE_GAUGE:
+                if (!isNodeStatusGaugeEnabled()) {
+                    return new NoOpMetricCollector<>();
+                }
+                return saveBuildCollector(new NodesOfflineGauge(labelNames, namespace, subsystem));
             case JENKINS_UPTIME_GAUGE:
                 return saveBuildCollector(new JenkinsUptimeGauge(labelNames, namespace, subsystem));
             case JENKINS_VERSION_INFO_GAUGE:
@@ -35,7 +40,7 @@
         }
     }
 
-    private boolean isNodeOnlineGaugeEnabled() {
+    private boolean isNodeStatusGaugeEnabled() {
         return PrometheusConfiguration.get().isCollectNodeStatus();
     }
 

src/main/java/org/jenkinsci/plugins/prometheus/collectors/jenkins/NodesOfflineGauge.java

@@ -0,0 +1,51 @@
+package org.jenkinsci.plugins.prometheus.collectors.jenkins;
+
+import hudson.model.Computer;
+import hudson.model.Node;
+import io.prometheus.client.Gauge;
+import io.prometheus.client.SimpleCollector;
+import jenkins.model.Jenkins;
+import org.jenkinsci.plugins.prometheus.collectors.BaseMetricCollector;
+import org.jenkinsci.plugins.prometheus.collectors.CollectorType;
+
+public class NodesOfflineGauge extends BaseMetricCollector<Jenkins, Gauge> {
+
+    NodesOfflineGauge(String[] labelNames, String namespace, String subsystem) {
+        super(labelNames, namespace, subsystem);
+    }
+
+    @Override
+    protected CollectorType getCollectorType() {
+        return CollectorType.NODES_OFFLINE_GAUGE;
+    }
+
+    @Override
+    protected String getHelpText() {
+        return "Jenkins nodes offline status"; 
+    }
+
+    @Override
+    protected SimpleCollector.Builder<?, Gauge> getCollectorBuilder() {
+        return Gauge.build();
+    }
+
+    @Override
+    public void calculateMetric(Jenkins jenkinsObject, String[] labelValues) {
+        if (jenkinsObject == null) {
+            return;
+        }
+        for (Node node : jenkinsObject.getNodes()) {
+            //Check whether the node is online or offline
+            Computer comp = node.toComputer();
+            if (comp == null) {
+                continue;
+            }
+
+            if (comp.isOffline()) { // https://javadoc.jenkins.io/hudson/model/Computer.html
+                this.collector.labels(node.getNodeName()).set(1);
+            } else {
+                this.collector.labels(node.getNodeName()).set(0);
+            }
+        }
+    }
+}

src/test/java/org/jenkinsci/plugins/prometheus/collectors/jenkins/JenkinsVersionInfoTest.java

@@ -42,9 +42,6 @@ public void testCollectResult() throws Exception {
 
     static void setFinalStatic(Field field, Object newValue) throws Exception {
         field.setAccessible(true);
-        Field modifiersField = Field.class.getDeclaredField("modifiers");
-        modifiersField.setAccessible(true);
-        modifiersField.setInt(field, field.getModifiers() & ~Modifier.FINAL);
         field.set(null, newValue);
     }
 

src/test/java/org/jenkinsci/plugins/prometheus/collectors/jenkins/NodesOfflineGaugeTest.java

@@ -0,0 +1,74 @@
+package org.jenkinsci.plugins.prometheus.collectors.jenkins;
+
+import hudson.model.Computer;
+import hudson.model.Node;
+import io.prometheus.client.Collector;
+import jenkins.model.Jenkins;
+
+import org.jenkinsci.plugins.prometheus.collectors.testutils.MockedJenkinsTest;
+import org.junit.Test;
+
+import java.lang.reflect.Field;
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+public class NodesOfflineGaugeTest extends MockedJenkinsTest {
+
+    @Test
+    public void testCollectResult() throws Exception {
+
+
+        setFinalStatic(Jenkins.class.getDeclaredField("VERSION"), "123");
+
+        List<Node> nodes = new ArrayList<>();
+        nodes.add(mockNode("node1", true));
+        nodes.add(mockNode("node2", false));
+        nodes.add(mockNode("node3", true));
+        nodes.add(mockNode("nullNode", false));
+        when(mock.getNodes()).thenReturn(nodes);
+
+        NodesOfflineGauge sut = new NodesOfflineGauge(new String[]{"node"}, getNamespace(), getSubSystem());
+        sut.calculateMetric(mock, getLabelValues());
+
+        List<Collector.MetricFamilySamples> collect = sut.collect();
+
+        validateMetricFamilySampleListSize(collect, 1);
+
+        Collector.MetricFamilySamples samples = collect.get(0);
+        // we pass 4 nodes but we only get 3 -> there's a node with null computer
+        validateMetricFamilySampleSize(samples, 3);
+        for (Collector.MetricFamilySamples.Sample sample : samples.samples) {
+            System.out.println(sample);
+            if (sample.labelValues.contains("node1")) {
+                validateValue(sample, 1.0);
+            }
+            if (sample.labelValues.contains("node2")) {
+                validateValue(sample, 0.0);
+            }
+            if (sample.labelValues.contains("node3")) {
+                validateValue(sample, 1.0);
+            }
+        }
+        System.out.println(samples);
+        validateNames(samples, new String[]{"default_jenkins_nodes_offline"});
+    }
+
+    private Node mockNode(String nodeName, boolean isOnline) {
+        Node nodeMock = mock(Node.class);
+        if (!"nullNode".equalsIgnoreCase(nodeName)) {
+            Computer computerMock = mock(Computer.class);
+            when(computerMock.isOffline()).thenReturn(isOnline);
+            when(nodeMock.toComputer()).thenReturn(computerMock);
+        }
+        when(nodeMock.getNodeName()).thenReturn(nodeName);
+        return nodeMock;
+    }
+
+    static void setFinalStatic(Field field, Object newValue) throws Exception {
+        field.setAccessible(true);
+        field.set(null, newValue);
+    }
+}

src/test/java/org/jenkinsci/plugins/prometheus/collectors/jenkins/NodesOnlineGaugeTest.java

@@ -70,9 +70,6 @@ private Node mockNode(String nodeName, boolean isOnline) {
 
     static void setFinalStatic(Field field, Object newValue) throws Exception {
         field.setAccessible(true);
-        Field modifiersField = Field.class.getDeclaredField("modifiers");
-        modifiersField.setAccessible(true);
-        modifiersField.setInt(field, field.getModifiers() & ~Modifier.FINAL);
         field.set(null, newValue);
     }
 }