Fix k8s api connection leak (#1848)

* Update submodule skywalking-ui

* Fix k8s api bugs

* Fix api connection leak

oap-server/server-cluster-plugin/cluster-kubernetes-plugin/src/main/java/org/apache/skywalking/oap/server/cluster/plugin/kubernetes/KubernetesCoordinator.java

@@ -92,6 +92,9 @@ public class KubernetesCoordinator implements ClusterRegister, ClusterNodesQuery
 
     private void generateRemoteNodes() {
         for (Event event : watch) {
+            if (event == null) {
+                break;
+            }
             logger.debug("Received event {} {}-{}", event.getType(), event.getUid(), event.getHost());
             switch (event.getType()) {
                 case "ADDED":

oap-server/server-cluster-plugin/cluster-kubernetes-plugin/src/main/java/org/apache/skywalking/oap/server/cluster/plugin/kubernetes/dependencies/NamespacedPodListWatch.java

@@ -18,7 +18,6 @@
 
 package org.apache.skywalking.oap.server.cluster.plugin.kubernetes.dependencies;
 
-import com.google.common.collect.Iterators;
 import com.google.common.reflect.TypeToken;
 import io.kubernetes.client.ApiClient;
 import io.kubernetes.client.ApiException;
@@ -28,9 +27,10 @@ import io.kubernetes.client.models.V1Pod;
 import io.kubernetes.client.util.Config;
 import io.kubernetes.client.util.Watch;
 import java.io.IOException;
-import java.util.Collections;
 import java.util.Iterator;
+import java.util.Objects;
 import java.util.concurrent.TimeUnit;
+import java.util.function.Supplier;
 import org.apache.skywalking.oap.server.cluster.plugin.kubernetes.Event;
 import org.apache.skywalking.oap.server.cluster.plugin.kubernetes.ReusableWatch;
 import org.slf4j.Logger;
@@ -83,16 +83,33 @@ public class NamespacedPodListWatch implements ReusableWatch<Event> {
     }
 
     @Override public Iterator<Event> iterator() {
-        try {
-            return Iterators.transform(watch.iterator(), response -> {
-                if (response == null) {
-                    throw new NullPointerException("Original event is null");
+        final Iterator<Watch.Response<V1Pod>> watchItr = watch.iterator();
+        return new Iterator<Event>() {
+            @Override public boolean hasNext() {
+                return wrap(watchItr::hasNext, false);
+            }
+
+            @Override public Event next() {
+                return wrap(() -> {
+                    final Watch.Response<V1Pod> response = watchItr.next();
+                    return new Event(response.type, response.object.getMetadata().getUid(), response.object.getStatus().getPodIP());
+                }, null);
+            }
+
+            private <R> R wrap(final Supplier<R> action, final R defaultValue) {
+                Objects.requireNonNull(action);
+                try {
+                    return action.get();
+                } catch (final Throwable t) {
+                    logger.trace("Throwable", t);
+                    try {
+                        watch.close();
+                    } catch (IOException e) {
+                        logger.error("Close watch error", e);
+                    }
                 }
-                return new Event(response.type, response.object.getMetadata().getUid(), response.object.getStatus().getPodIP());
-            });
-        } catch (final RuntimeException exp) {
-            logger.trace("Runtime exception", exp);
-        }
-        return Collections.emptyIterator();
+                return defaultValue;
+            }
+        };
     }
 }