[ZEPPELIN-5270] Implementing a soft shutdown for K8s interpreters

zeppelin-plugins/launcher/k8s-standard/src/main/java/org/apache/zeppelin/interpreter/launcher/K8sRemoteInterpreterProcess.java

@@ -25,13 +25,15 @@
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Properties;
+import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 
 import org.apache.commons.io.IOUtils;
 import org.apache.commons.lang3.ArrayUtils;
 import org.apache.commons.lang3.RandomStringUtils;
 import org.apache.commons.lang3.StringUtils;
 import org.apache.zeppelin.interpreter.remote.RemoteInterpreterManagedProcess;
+import org.apache.zeppelin.interpreter.remote.RemoteInterpreterServer;
 import org.apache.zeppelin.interpreter.remote.RemoteInterpreterUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -46,6 +48,7 @@
 import io.fabric8.kubernetes.api.model.PodStatus;
 import io.fabric8.kubernetes.client.KubernetesClient;
 import io.fabric8.kubernetes.client.LocalPortForward;
+import io.fabric8.kubernetes.client.Watch;
 import io.fabric8.kubernetes.client.dsl.ParameterNamespaceListVisitFromServerGetDeleteRecreateWaitApplicable;
 
 public class K8sRemoteInterpreterProcess extends RemoteInterpreterManagedProcess {
@@ -143,16 +146,16 @@ public void start(String userName) throws IOException {
 
     // special handling if we doesn't want timeout the process during lifecycle phase pending
     if (!timeoutDuringPending) {
-      while (!StringUtils.equalsAnyIgnoreCase(getPodPhase(), "Succeeded", "Failed", "Running")
-          && !Thread.currentThread().isInterrupted()) {
-        try {
-          Thread.sleep(1000);
-        } catch (InterruptedException e) {
-          LOGGER.error("Interrupt received during pending phase. Try to stop the interpreter and interrupt the current thread.", e);
-          processStopped("Start process was interrupted during the pending phase");
-          stop();
-          Thread.currentThread().interrupt();
-        }
+      // WATCH
+      PodPhaseWatcher podWatcher = new PodPhaseWatcher(
+          phase -> StringUtils.equalsAnyIgnoreCase(phase, "Succeeded", "Failed", "Running"));
+      try (Watch watch = client.pods().inNamespace(namespace).withName(podName).watch(podWatcher)) {
+        podWatcher.getCountDownLatch().await();
+      } catch (InterruptedException e) {
+        LOGGER.error("Interrupt received during waiting for Running phase. Try to stop the interpreter and interrupt the current thread.", e);
+        processStopped("Start process was interrupted during waiting for Running phase");
+        stop();
+        Thread.currentThread().interrupt();
       }
     }
 
@@ -183,6 +186,18 @@ public void start(String userName) throws IOException {
   @Override
   public void stop() {
     super.stop();
+    // WATCH for soft shutdown
+    PodPhaseWatcher podWatcher = new PodPhaseWatcher(phase -> StringUtils.equalsAny(phase, "Succeeded", "Failed"));
+    try (Watch watch = client.pods().inNamespace(namespace).withName(podName).watch(podWatcher)) {
+      if (!podWatcher.getCountDownLatch().await(RemoteInterpreterServer.DEFAULT_SHUTDOWN_TIMEOUT + 500,
+          TimeUnit.MILLISECONDS)) {
+        LOGGER.warn("Pod {} doesn't terminate in time", podName);
+      }
+    } catch (InterruptedException e) {
+      LOGGER.error("Interruption received while waiting for stop.", e);
+      processStopped("Stop process was interrupted during termination");
+      Thread.currentThread().interrupt();
+    }
     Properties templateProperties = getTemplateBindings(null);
     // delete pod
     try {

zeppelin-plugins/launcher/k8s-standard/src/main/java/org/apache/zeppelin/interpreter/launcher/PodPhaseWatcher.java

@@ -0,0 +1,64 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.zeppelin.interpreter.launcher;
+
+import java.util.concurrent.CountDownLatch;
+import java.util.function.Predicate;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import io.fabric8.kubernetes.api.model.Pod;
+import io.fabric8.kubernetes.api.model.PodStatus;
+import io.fabric8.kubernetes.client.KubernetesClientException;
+import io.fabric8.kubernetes.client.Watcher;
+
+public class PodPhaseWatcher implements Watcher<Pod> {
+  private static final Logger LOGGER = LoggerFactory.getLogger(PodPhaseWatcher.class);
+  private final CountDownLatch countDownLatch;
+  private final Predicate<String> predicate;
+
+  public PodPhaseWatcher(Predicate<String> predicate) {
+    this.countDownLatch = new CountDownLatch(1);
+    this.predicate = predicate;
+  }
+
+  @Override
+  public void eventReceived(Action action, Pod pod) {
+    PodStatus status = pod.getStatus();
+    if (status != null && predicate.test(status.getPhase())) {
+      LOGGER.info("Pod {} meets phase {}", pod.getMetadata().getName(), status.getPhase());
+      countDownLatch.countDown();
+    }
+  }
+
+  @Override
+  public void onClose(KubernetesClientException cause) {
+    if (cause != null) {
+      LOGGER.error("PodWatcher exits abnormally", cause);
+    }
+    // always count down, so threads that are waiting will continue
+    countDownLatch.countDown();
+  }
+
+  public CountDownLatch getCountDownLatch() {
+    return countDownLatch;
+  }
+
+}

zeppelin-plugins/launcher/k8s-standard/src/test/java/org/apache/zeppelin/interpreter/launcher/PodPhaseWatcherTest.java

@@ -0,0 +1,92 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.zeppelin.interpreter.launcher;
+
+import static org.junit.Assert.*;
+
+import java.util.concurrent.TimeUnit;
+
+import org.apache.commons.lang3.StringUtils;
+import org.junit.Rule;
+import org.junit.Test;
+
+import io.fabric8.kubernetes.api.model.Pod;
+import io.fabric8.kubernetes.api.model.PodBuilder;
+import io.fabric8.kubernetes.api.model.PodList;
+import io.fabric8.kubernetes.api.model.PodStatus;
+import io.fabric8.kubernetes.api.model.PodStatusBuilder;
+import io.fabric8.kubernetes.client.KubernetesClient;
+import io.fabric8.kubernetes.client.Watch;
+import io.fabric8.kubernetes.client.server.mock.KubernetesServer;
+
+public class PodPhaseWatcherTest {
+
+  @Rule
+  public KubernetesServer server = new KubernetesServer(true, true);
+
+  @Test
+  public void testPhase() throws InterruptedException {
+    KubernetesClient client = server.getClient();
+    // CREATE
+    client.pods().inNamespace("ns1")
+        .create(new PodBuilder().withNewMetadata().withName("pod1").endMetadata().build());
+    // READ
+    PodList podList = client.pods().inNamespace("ns1").list();
+    assertNotNull(podList);
+    assertEquals(1, podList.getItems().size());
+    Pod pod = podList.getItems().get(0);
+    // WATCH
+    PodPhaseWatcher podWatcher = new PodPhaseWatcher(
+        phase -> StringUtils.equalsAnyIgnoreCase(phase, "Succeeded", "Failed", "Running"));
+    Watch watch = client.pods().inNamespace("ns1").withName("pod1").watch(podWatcher);
+
+    // Update Pod to "pending" phase
+    pod.setStatus(new PodStatus(null, null, null, null, null, null, null, "Pending", null, null,
+        null, null, null));
+    client.pods().inNamespace("ns1").updateStatus(pod);
+
+    // Update Pod to "Running" phase
+    pod.setStatus(new PodStatusBuilder(new PodStatus(null, null, null, null, null, null, null,
+        "Running", null, null, null, null, null)).build());
+    client.pods().inNamespace("ns1").updateStatus(pod);
+
+    assertTrue(podWatcher.getCountDownLatch().await(1, TimeUnit.SECONDS));
+    watch.close();
+  }
+
+  @Test
+  public void testPhaseWithError() throws InterruptedException {
+    KubernetesClient client = server.getClient();
+    // CREATE
+    client.pods().inNamespace("ns1")
+        .create(new PodBuilder().withNewMetadata().withName("pod1").endMetadata().build());
+    // READ
+    PodList podList = client.pods().inNamespace("ns1").list();
+    assertNotNull(podList);
+    assertEquals(1, podList.getItems().size());
+    // WATCH
+    PodPhaseWatcher podWatcher = new PodPhaseWatcher(
+        phase -> StringUtils.equalsAnyIgnoreCase(phase, "Succeeded", "Failed", "Running"));
+    Watch watch = client.pods().inNamespace("ns1").withName("pod1").watch(podWatcher);
+
+    // In the case of close, we do not block thread execution
+    watch.close();
+    assertTrue(podWatcher.getCountDownLatch().await(1, TimeUnit.SECONDS));
+  }
+}