A better way to unregister is to listen to nodes deletion

Author: Vlatombe

src/main/java/org/csanchez/jenkins/plugins/kubernetes/KubernetesCloud.java

@@ -568,10 +568,6 @@ public Collection<NodeProvisioner.PlannedNode> provision(@NonNull final Cloud.Cl
         return Collections.emptyList();
     }
 
-    public void onTerminate(@NonNull KubernetesSlave slave) {
-        KubernetesProvisioningLimits.get().unregister(slave.getKubernetesCloud(), slave.getTemplate(), slave.getNumExecutors());
-    }
-
     @Override
     public boolean canProvision(@NonNull Cloud.CloudState state) {
         return getTemplate(state.getLabel()) != null;

src/main/java/org/csanchez/jenkins/plugins/kubernetes/KubernetesProvisioningLimits.java

@@ -6,9 +6,11 @@
 import hudson.ExtensionList;
 import hudson.init.InitMilestone;
 import hudson.init.Initializer;
+import hudson.model.Node;
 import hudson.model.Queue;
 import jenkins.metrics.api.Metrics;
 import jenkins.model.Jenkins;
+import jenkins.model.NodeListener;
 
 import javax.annotation.Nonnull;
 import java.util.Collections;
@@ -130,4 +132,15 @@ AtomicInteger getPodTemplateCount(String id) {
         return podTemplateCounts.computeIfAbsent(id, k -> new AtomicInteger());
     }
 
+    @Extension
+    public static class NodeListenerImpl extends NodeListener {
+        @Override
+        protected void onDeleted(@Nonnull Node node) {
+            if (node instanceof KubernetesSlave) {
+                KubernetesSlave kubernetesNode = (KubernetesSlave) node;
+                KubernetesProvisioningLimits.get().unregister(kubernetesNode.getKubernetesCloud(), kubernetesNode.getTemplate(), node.getNumExecutors());
+            }
+        }
+    }
+
 }

src/main/java/org/csanchez/jenkins/plugins/kubernetes/KubernetesSlave.java

@@ -293,7 +293,6 @@ protected void _terminate(TaskListener listener) throws IOException, Interrupted
             LOGGER.log(Level.SEVERE, String.format("Unable to terminate agent %s. Cloud may have been removed. There may be leftover resources on the Kubernetes cluster.", name));
             return;
         }
-        cloud.onTerminate(this);
 
         KubernetesClient client;
         try {