YARN-8761. Service AM support for decommissioning component instances.

           Contributed by Billie Rinaldi

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-api/src/main/java/org/apache/hadoop/yarn/service/client/ApiServiceClient.java

@@ -746,4 +746,32 @@ public class ApiServiceClient extends AppAdminClient {
     }
     return result;
   }
+
+  @Override
+  public int actionDecommissionInstances(String appName, List<String>
+      componentInstances) throws IOException, YarnException {
+    int result = EXIT_SUCCESS;
+    try {
+      Service service = new Service();
+      service.setName(appName);
+      for (String instance : componentInstances) {
+        String componentName = ServiceApiUtil.parseComponentName(instance);
+        Component component = service.getComponent(componentName);
+        if (component == null) {
+          component = new Component();
+          component.setName(componentName);
+          service.addComponent(component);
+        }
+        component.addDecommissionedInstance(instance);
+      }
+      String buffer = jsonSerDeser.toJson(service);
+      ClientResponse response = getApiClient(getServicePath(appName))
+          .put(ClientResponse.class, buffer);
+      result = processResponse(response);
+    } catch (Exception e) {
+      LOG.error("Fail to decommission instance: ", e);
+      result = EXIT_EXCEPTION_THROWN;
+    }
+    return result;
+  }
 }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-api/src/main/java/org/apache/hadoop/yarn/service/webapp/ApiServer.java

@@ -458,6 +458,12 @@ public class ApiServer {
           && updateServiceData.getLifetime() > 0) {
         return updateLifetime(appName, updateServiceData, ugi);
       }
+
+      for (Component c : updateServiceData.getComponents()) {
+        if (c.getDecommissionedInstances().size() > 0) {
+          return decommissionInstances(updateServiceData, ugi);
+        }
+      }
     } catch (UndeclaredThrowableException e) {
       return formatResponse(Status.BAD_REQUEST,
           e.getCause().getMessage());
@@ -795,6 +801,40 @@ public class ApiServer {
     });
   }
 
+  private Response decommissionInstances(Service service, UserGroupInformation
+      ugi) throws IOException, InterruptedException {
+    String appName = service.getName();
+    Response response = Response.status(Status.BAD_REQUEST).build();
+
+    List<String> instances = new ArrayList<>();
+    for (Component c : service.getComponents()) {
+      instances.addAll(c.getDecommissionedInstances());
+    }
+    Integer result = ugi.doAs(new PrivilegedExceptionAction<Integer>() {
+      @Override
+      public Integer run() throws YarnException, IOException {
+        int result = 0;
+        ServiceClient sc = new ServiceClient();
+        sc.init(YARN_CONFIG);
+        sc.start();
+        result = sc
+            .actionDecommissionInstances(appName, instances);
+        sc.close();
+        return Integer.valueOf(result);
+      }
+    });
+    if (result == EXIT_SUCCESS) {
+      String message = "Service " + appName + " has successfully " +
+          "decommissioned instances.";
+      LOG.info(message);
+      ServiceStatus status = new ServiceStatus();
+      status.setDiagnostics(message);
+      status.setState(ServiceState.ACCEPTED);
+      response = formatResponse(Status.ACCEPTED, status);
+    }
+    return response;
+  }
+
   private Service getServiceFromClient(UserGroupInformation ugi,
       String serviceName) throws IOException, InterruptedException {
 

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-api/src/main/resources/definition/YARN-Simplified-V1-API-Layer-For-Services.yaml

@@ -525,6 +525,11 @@ definitions:
         type: integer
         format: int64
         description: Number of containers for this component (optional). If not specified, the service level global number_of_containers takes effect.
+      decommissioned_instances:
+        type: array
+        items:
+          type: string
+        description: List of decommissioned component instances.
       containers:
         type: array
         description: Containers of a started component. Specifying a value for this attribute for the POST payload raises a validation error. This blob is available only in the GET response of a started service.

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/main/java/org/apache/hadoop/yarn/service/ClientAMProtocol.java

@@ -23,6 +23,8 @@ import org.apache.hadoop.yarn.proto.ClientAMProtocol.CancelUpgradeRequestProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.CancelUpgradeResponseProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.CompInstancesUpgradeResponseProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.CompInstancesUpgradeRequestProto;
+import org.apache.hadoop.yarn.proto.ClientAMProtocol.DecommissionCompInstancesRequestProto;
+import org.apache.hadoop.yarn.proto.ClientAMProtocol.DecommissionCompInstancesResponseProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.FlexComponentsRequestProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.FlexComponentsResponseProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.GetCompInstancesRequestProto;
@@ -65,4 +67,8 @@ public interface ClientAMProtocol {
 
   CancelUpgradeResponseProto cancelUpgrade(
       CancelUpgradeRequestProto request) throws IOException, YarnException;
+
+  DecommissionCompInstancesResponseProto decommissionCompInstances(
+      DecommissionCompInstancesRequestProto request) throws IOException,
+      YarnException;
 }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/main/java/org/apache/hadoop/yarn/service/ClientAMService.java

@@ -35,6 +35,8 @@ import org.apache.hadoop.yarn.proto.ClientAMProtocol.CancelUpgradeResponseProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.CompInstancesUpgradeRequestProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.CompInstancesUpgradeResponseProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.ComponentCountProto;
+import org.apache.hadoop.yarn.proto.ClientAMProtocol.DecommissionCompInstancesRequestProto;
+import org.apache.hadoop.yarn.proto.ClientAMProtocol.DecommissionCompInstancesResponseProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.FlexComponentsRequestProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.FlexComponentsResponseProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.GetCompInstancesRequestProto;
@@ -60,6 +62,7 @@ import java.io.IOException;
 import java.net.InetSocketAddress;
 import java.util.List;
 
+import static org.apache.hadoop.yarn.service.component.ComponentEventType.DECOMMISSION_INSTANCE;
 import static org.apache.hadoop.yarn.service.component.ComponentEventType.FLEX;
 
 public class ClientAMService extends AbstractService
@@ -221,4 +224,21 @@ public class ClientAMService extends AbstractService
     context.scheduler.getDispatcher().getEventHandler().handle(event);
     return CancelUpgradeResponseProto.newBuilder().build();
   }
+
+  @Override
+  public DecommissionCompInstancesResponseProto decommissionCompInstances(
+      DecommissionCompInstancesRequestProto request)
+      throws IOException, YarnException {
+    if (!request.getCompInstancesList().isEmpty()) {
+      for (String instance : request.getCompInstancesList()) {
+        String componentName = ServiceApiUtil.parseComponentName(instance);
+        ComponentEvent event = new ComponentEvent(componentName,
+            DECOMMISSION_INSTANCE).setInstanceName(instance);
+        context.scheduler.getDispatcher().getEventHandler().handle(event);
+        LOG.info("Decommissioning component {} instance {}", componentName,
+            instance);
+      }
+    }
+    return DecommissionCompInstancesResponseProto.newBuilder().build();
+  }
 }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/main/java/org/apache/hadoop/yarn/service/api/records/Component.java

@@ -79,6 +79,10 @@ public class Component implements Serializable {
   @XmlElement(name = "number_of_containers")
   private Long numberOfContainers = null;
 
+  @JsonProperty("decommissioned_instances")
+  @XmlElement(name = "decommissioned_instances")
+  private List<String> decommissionedInstances = new ArrayList<>();
+
   @JsonProperty("run_privileged_container")
   @XmlElement(name = "run_privileged_container")
   private Boolean runPrivilegedContainer = false;
@@ -295,6 +299,28 @@ public class Component implements Serializable {
     this.numberOfContainers = numberOfContainers;
   }
 
+  /**
+   * A list of decommissioned component instances.
+   **/
+  public Component decommissionedInstances(List<String>
+      decommissionedInstances) {
+    this.decommissionedInstances = decommissionedInstances;
+    return this;
+  }
+
+  @ApiModelProperty(example = "null", value = "A list of decommissioned component instances.")
+  public List<String> getDecommissionedInstances() {
+    return decommissionedInstances;
+  }
+
+  public void setDecommissionedInstances(List<String> decommissionedInstances) {
+    this.decommissionedInstances = decommissionedInstances;
+  }
+
+  public void addDecommissionedInstance(String componentInstanceName) {
+    this.decommissionedInstances.add(componentInstanceName);
+  }
+
   @ApiModelProperty(example = "null", value = "Containers of a started component. Specifying a value for this attribute for the POST payload raises a validation error. This blob is available only in the GET response of a started service.")
   public List<Container> getContainers() {
     return containers;

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/main/java/org/apache/hadoop/yarn/service/client/ServiceClient.java

@@ -62,6 +62,7 @@ import org.apache.hadoop.yarn.ipc.YarnRPC;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.CancelUpgradeRequestProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.CompInstancesUpgradeRequestProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.ComponentCountProto;
+import org.apache.hadoop.yarn.proto.ClientAMProtocol.DecommissionCompInstancesRequestProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.FlexComponentsRequestProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.GetCompInstancesRequestProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.GetCompInstancesResponseProto;
@@ -401,6 +402,61 @@ public class ServiceClient extends AppAdminClient implements SliderExitCodes,
     return EXIT_SUCCESS;
   }
 
+  @Override
+  public int actionDecommissionInstances(String appName,
+      List<String> componentInstances) throws IOException, YarnException {
+    checkAppExistOnHdfs(appName);
+    Service persistedService = ServiceApiUtil.loadService(fs, appName);
+    if (StringUtils.isEmpty(persistedService.getId())) {
+      throw new YarnException(
+          persistedService.getName() + " appId is null, may be not submitted " +
+              "to YARN yet");
+    }
+    cachedAppInfo.put(persistedService.getName(), new AppInfo(
+        ApplicationId.fromString(persistedService.getId()), persistedService
+        .getKerberosPrincipal().getPrincipalName()));
+
+    for (String instance : componentInstances) {
+      String componentName = ServiceApiUtil.parseComponentName(
+          ServiceApiUtil.parseAndValidateComponentInstanceName(instance,
+              appName, getConfig()));
+      Component component = persistedService.getComponent(componentName);
+      if (component == null) {
+        throw new IllegalArgumentException(instance + " does not exist !");
+      }
+      if (!component.getDecommissionedInstances().contains(instance)) {
+        component.addDecommissionedInstance(instance);
+        component.setNumberOfContainers(Math.max(0, component
+            .getNumberOfContainers() - 1));
+      }
+    }
+    ServiceApiUtil.writeAppDefinition(fs, persistedService);
+
+    ApplicationReport appReport =
+        yarnClient.getApplicationReport(ApplicationId.fromString(
+            persistedService.getId()));
+    if (appReport.getYarnApplicationState() != RUNNING) {
+      String message =
+          persistedService.getName() + " is at " + appReport
+              .getYarnApplicationState() + " state, decommission can only be " +
+              "invoked when service is running";
+      LOG.error(message);
+      throw new YarnException(message);
+    }
+
+    if (StringUtils.isEmpty(appReport.getHost())) {
+      throw new YarnException(persistedService.getName() + " AM hostname is " +
+          "empty");
+    }
+    ClientAMProtocol proxy =
+        createAMProxy(persistedService.getName(), appReport);
+    DecommissionCompInstancesRequestProto.Builder requestBuilder =
+        DecommissionCompInstancesRequestProto.newBuilder();
+    requestBuilder.addAllCompInstances(componentInstances);
+    proxy.decommissionCompInstances(requestBuilder.build());
+    return EXIT_SUCCESS;
+  }
+
   @Override
   public int actionCleanUp(String appName, String userName) throws
       IOException, YarnException {
@@ -605,9 +661,7 @@ public class ServiceClient extends AppAdminClient implements SliderExitCodes,
       throw new YarnException("Components " + componentCounts.keySet()
           + " do not exist in app definition.");
     }
-    jsonSerDeser
-        .save(fs.getFileSystem(), ServiceApiUtil.getServiceJsonPath(fs, serviceName),
-            persistedService, true);
+    ServiceApiUtil.writeAppDefinition(fs, persistedService);
 
     ApplicationId appId = getAppId(serviceName);
     if (appId == null) {

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/main/java/org/apache/hadoop/yarn/service/component/Component.java

@@ -57,6 +57,7 @@ import org.apache.hadoop.yarn.service.monitor.probe.MonitorUtils;
 import org.apache.hadoop.yarn.service.monitor.probe.Probe;
 import org.apache.hadoop.yarn.service.containerlaunch.ContainerLaunchService;
 import org.apache.hadoop.yarn.service.provider.ProviderUtils;
+import org.apache.hadoop.yarn.service.utils.ServiceApiUtil;
 import org.apache.hadoop.yarn.service.utils.ServiceUtils;
 import org.apache.hadoop.yarn.state.InvalidStateTransitionException;
 import org.apache.hadoop.yarn.state.MultipleArcTransition;
@@ -142,6 +143,9 @@ public class Component implements EventHandler<ComponentEvent> {
           // container recovered on AM restart
           .addTransition(INIT, INIT, CONTAINER_RECOVERED,
               new ContainerRecoveredTransition())
+          // instance decommissioned
+          .addTransition(INIT, INIT, DECOMMISSION_INSTANCE,
+              new DecommissionInstanceTransition())
 
           // container recovered in AM heartbeat
           .addTransition(FLEXING, FLEXING, CONTAINER_RECOVERED,
@@ -161,6 +165,9 @@ public class Component implements EventHandler<ComponentEvent> {
               new FlexComponentTransition())
           .addTransition(FLEXING, EnumSet.of(UPGRADING, FLEXING, STABLE),
               CHECK_STABLE, new CheckStableTransition())
+          // instance decommissioned
+          .addTransition(FLEXING, FLEXING, DECOMMISSION_INSTANCE,
+              new DecommissionInstanceTransition())
 
           // container failed while stable
           .addTransition(STABLE, FLEXING, CONTAINER_COMPLETED,
@@ -173,6 +180,10 @@ public class Component implements EventHandler<ComponentEvent> {
           // For flex down, go to STABLE state
           .addTransition(STABLE, EnumSet.of(STABLE, FLEXING),
               FLEX, new FlexComponentTransition())
+          // instance decommissioned
+          .addTransition(STABLE, STABLE, DECOMMISSION_INSTANCE,
+              new DecommissionInstanceTransition())
+          // upgrade component
           .addTransition(STABLE, UPGRADING, UPGRADE,
               new NeedsUpgradeTransition())
           .addTransition(STABLE, CANCEL_UPGRADING, CANCEL_UPGRADE,
@@ -187,6 +198,9 @@ public class Component implements EventHandler<ComponentEvent> {
               CHECK_STABLE, new CheckStableTransition())
           .addTransition(UPGRADING, UPGRADING, CONTAINER_COMPLETED,
               new CompletedAfterUpgradeTransition())
+          // instance decommissioned
+          .addTransition(UPGRADING, UPGRADING, DECOMMISSION_INSTANCE,
+              new DecommissionInstanceTransition())
 
           .addTransition(CANCEL_UPGRADING, EnumSet.of(CANCEL_UPGRADING, FLEXING,
               STABLE), CHECK_STABLE, new CheckStableTransition())
@@ -194,7 +208,9 @@ public class Component implements EventHandler<ComponentEvent> {
               CONTAINER_COMPLETED, new CompletedAfterUpgradeTransition())
           .addTransition(CANCEL_UPGRADING, FLEXING, CONTAINER_ALLOCATED,
               new ContainerAllocatedTransition())
-
+          // instance decommissioned
+          .addTransition(CANCEL_UPGRADING, CANCEL_UPGRADING,
+              DECOMMISSION_INSTANCE, new DecommissionInstanceTransition())
           .installTopology();
 
   public Component(
@@ -241,6 +257,11 @@ public class Component implements EventHandler<ComponentEvent> {
     ComponentInstanceId id =
         new ComponentInstanceId(instanceIdCounter.getAndIncrement(),
             componentSpec.getName());
+    while (componentSpec.getDecommissionedInstances().contains(id
+        .getCompInstanceName())) {
+      id = new ComponentInstanceId(instanceIdCounter.getAndIncrement(),
+          componentSpec.getName());
+    }
     ComponentInstance instance = new ComponentInstance(this, id);
     compInstances.put(instance.getCompInstanceName(), instance);
     pendingInstances.add(instance);
@@ -377,6 +398,38 @@ public class Component implements EventHandler<ComponentEvent> {
     }
   }
 
+  private static class DecommissionInstanceTransition extends BaseTransition {
+    @Override
+    public void transition(Component component, ComponentEvent event) {
+      String instanceName = event.getInstanceName();
+      String hostnameSuffix = component.getHostnameSuffix();
+      if (instanceName.endsWith(hostnameSuffix)) {
+        instanceName = instanceName.substring(0,
+            instanceName.length() - hostnameSuffix.length());
+      }
+      if (component.getComponentSpec().getDecommissionedInstances()
+          .contains(instanceName)) {
+        LOG.info("Instance {} already decommissioned", instanceName);
+        return;
+      }
+      component.getComponentSpec().addDecommissionedInstance(instanceName);
+      ComponentInstance instance = component.getComponentInstance(instanceName);
+      if (instance == null) {
+        LOG.info("Instance was null for decommissioned instance {}",
+            instanceName);
+        return;
+      }
+      // remove the instance
+      component.compInstances.remove(instance.getCompInstanceName());
+      component.pendingInstances.remove(instance);
+      component.scheduler.getServiceMetrics().containersDesired.decr();
+      component.componentMetrics.containersDesired.decr();
+      component.getComponentSpec().setNumberOfContainers(component
+          .getComponentSpec().getNumberOfContainers() - 1);
+      instance.destroy();
+    }
+  }
+
   private static class ContainerAllocatedTransition extends BaseTransition {
     @Override
     public void transition(Component component, ComponentEvent event) {
@@ -808,10 +861,8 @@ public class Component implements EventHandler<ComponentEvent> {
 
   private void setDesiredContainers(int n) {
     int delta = n - scheduler.getServiceMetrics().containersDesired.value();
-    if (delta > 0) {
+    if (delta != 0) {
       scheduler.getServiceMetrics().containersDesired.incr(delta);
-    } else {
-      scheduler.getServiceMetrics().containersDesired.decr(delta);
     }
     componentMetrics.containersDesired.set(n);
   }
@@ -1203,4 +1254,9 @@ public class Component implements EventHandler<ComponentEvent> {
     RestartPolicyEnum restartPolicyEnum = getComponentSpec().getRestartPolicy();
     return getRestartPolicyHandler(restartPolicyEnum);
   }
+
+  public String getHostnameSuffix() {
+    return ServiceApiUtil.getHostnameSuffix(context.service.getName(),
+        scheduler.getConfig());
+  }
 }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/main/java/org/apache/hadoop/yarn/service/component/ComponentEvent.java

@@ -31,6 +31,7 @@ public class ComponentEvent extends AbstractEvent<ComponentEventType> {
   private final ComponentEventType type;
   private Container container;
   private ComponentInstance instance;
+  private String instanceName;
   private ContainerStatus status;
   private ContainerId containerId;
   private org.apache.hadoop.yarn.service.api.records.Component targetSpec;
@@ -86,6 +87,15 @@ public class ComponentEvent extends AbstractEvent<ComponentEventType> {
     return this;
   }
 
+  public String getInstanceName() {
+    return instanceName;
+  }
+
+  public ComponentEvent setInstanceName(String instanceName) {
+    this.instanceName = instanceName;
+    return this;
+  }
+
   public ContainerStatus getStatus() {
     return status;
   }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/main/java/org/apache/hadoop/yarn/service/component/ComponentEventType.java

@@ -26,5 +26,6 @@ public enum ComponentEventType {
   CONTAINER_COMPLETED,
   CANCEL_UPGRADE,
   UPGRADE,
-  CHECK_STABLE
+  CHECK_STABLE,
+  DECOMMISSION_INSTANCE
 }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/main/java/org/apache/hadoop/yarn/service/component/instance/ComponentInstance.java

@@ -21,9 +21,7 @@ package org.apache.hadoop.yarn.service.component.instance;
 import com.google.common.annotations.VisibleForTesting;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
-import org.apache.hadoop.registry.client.api.RegistryConstants;
 import org.apache.hadoop.registry.client.binding.RegistryPathUtils;
-import org.apache.hadoop.registry.client.binding.RegistryUtils;
 import org.apache.hadoop.registry.client.types.ServiceRecord;
 import org.apache.hadoop.registry.client.types.yarn.PersistencePolicies;
 import org.apache.hadoop.util.StringUtils;
@@ -913,21 +911,7 @@ public class ComponentInstance implements EventHandler<ComponentInstanceEvent>,
   }
 
   public String getHostname() {
-    String domain = getComponent().getScheduler().getConfig()
-        .get(RegistryConstants.KEY_DNS_DOMAIN);
-    String hostname;
-    if (domain == null || domain.isEmpty()) {
-      hostname = MessageFormat
-          .format("{0}.{1}.{2}", getCompInstanceName(),
-              getComponent().getContext().service.getName(),
-              RegistryUtils.currentUser());
-    } else {
-      hostname = MessageFormat
-          .format("{0}.{1}.{2}.{3}", getCompInstanceName(),
-              getComponent().getContext().service.getName(),
-              RegistryUtils.currentUser(), domain);
-    }
-    return hostname;
+    return getCompInstanceName() + getComponent().getHostnameSuffix();
   }
 
   @Override

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/main/java/org/apache/hadoop/yarn/service/impl/pb/client/ClientAMProtocolPBClientImpl.java

@@ -34,6 +34,8 @@ import org.apache.hadoop.yarn.proto.ClientAMProtocol.CancelUpgradeRequestProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.CancelUpgradeResponseProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.CompInstancesUpgradeResponseProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.CompInstancesUpgradeRequestProto;
+import org.apache.hadoop.yarn.proto.ClientAMProtocol.DecommissionCompInstancesRequestProto;
+import org.apache.hadoop.yarn.proto.ClientAMProtocol.DecommissionCompInstancesResponseProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.FlexComponentsRequestProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.FlexComponentsResponseProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.GetCompInstancesRequestProto;
@@ -154,4 +156,16 @@ public class ClientAMProtocolPBClientImpl
     }
     return null;
   }
+
+  @Override
+  public DecommissionCompInstancesResponseProto decommissionCompInstances(
+      DecommissionCompInstancesRequestProto request)
+      throws IOException, YarnException {
+    try {
+      return proxy.decommissionCompInstances(null, request);
+    } catch (ServiceException e) {
+      RPCUtil.unwrapAndThrowException(e);
+    }
+    return null;
+  }
 }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/main/java/org/apache/hadoop/yarn/service/impl/pb/service/ClientAMProtocolPBServiceImpl.java

@@ -25,6 +25,8 @@ import org.apache.hadoop.yarn.proto.ClientAMProtocol.CancelUpgradeRequestProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.CancelUpgradeResponseProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.CompInstancesUpgradeRequestProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.CompInstancesUpgradeResponseProto;
+import org.apache.hadoop.yarn.proto.ClientAMProtocol.DecommissionCompInstancesRequestProto;
+import org.apache.hadoop.yarn.proto.ClientAMProtocol.DecommissionCompInstancesResponseProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.FlexComponentsRequestProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.FlexComponentsResponseProto;
 import org.apache.hadoop.yarn.proto.ClientAMProtocol.GetCompInstancesRequestProto;
@@ -129,4 +131,15 @@ public class ClientAMProtocolPBServiceImpl implements ClientAMProtocolPB {
       throw new ServiceException(e);
     }
   }
+
+  @Override
+  public DecommissionCompInstancesResponseProto decommissionCompInstances(
+      RpcController controller, DecommissionCompInstancesRequestProto
+      request) throws ServiceException {
+    try {
+      return real.decommissionCompInstances(request);
+    } catch (IOException | YarnException e) {
+      throw new ServiceException(e);
+    }
+  }
 }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/main/java/org/apache/hadoop/yarn/service/utils/ServiceApiUtil.java

@@ -56,6 +56,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
+import java.text.MessageFormat;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashSet;
@@ -551,6 +552,13 @@ public class ServiceApiUtil {
     return appJson;
   }
 
+  public static Path writeAppDefinition(SliderFileSystem fs, Service service)
+      throws IOException {
+    Path appJson = getServiceJsonPath(fs, service.getName());
+    jsonSerDeser.save(fs.getFileSystem(), appJson, service, true);
+    return appJson;
+  }
+
   public static List<Container> getLiveContainers(Service service,
       List<String> componentInstances)
       throws YarnException {
@@ -660,9 +668,53 @@ public class ServiceApiUtil {
     return containerNeedUpgrade;
   }
 
-  private static String parseComponentName(String componentInstanceName)
+  public static String getHostnameSuffix(String serviceName, org.apache
+      .hadoop.conf.Configuration conf) {
+    String domain = conf.get(RegistryConstants.KEY_DNS_DOMAIN);
+    String hostnameSuffix;
+    if (domain == null || domain.isEmpty()) {
+      hostnameSuffix = MessageFormat
+          .format(".{0}.{1}", serviceName, RegistryUtils.currentUser());
+    } else {
+      hostnameSuffix = MessageFormat
+          .format(".{0}.{1}.{2}", serviceName,
+              RegistryUtils.currentUser(), domain);
+    }
+    return hostnameSuffix;
+  }
+
+  public static String parseAndValidateComponentInstanceName(String
+      instanceOrHostname, String serviceName, org.apache.hadoop.conf
+      .Configuration conf) throws IllegalArgumentException {
+    int idx = instanceOrHostname.indexOf('.');
+    String hostnameSuffix = getHostnameSuffix(serviceName, conf);
+    if (idx != -1) {
+      if (!instanceOrHostname.endsWith(hostnameSuffix)) {
+        throw new IllegalArgumentException("Specified hostname " +
+            instanceOrHostname + " does not have the expected format " +
+            "componentInstanceName" +
+            hostnameSuffix);
+      }
+      instanceOrHostname = instanceOrHostname.substring(0, instanceOrHostname
+          .length() - hostnameSuffix.length());
+    }
+    idx = instanceOrHostname.indexOf('.');
+    if (idx != -1) {
+      throw new IllegalArgumentException("Specified hostname " +
+          instanceOrHostname + " does not have the expected format " +
+          "componentInstanceName" +
+          hostnameSuffix);
+    }
+    return instanceOrHostname;
+  }
+
+  public static String parseComponentName(String componentInstanceName)
       throws YarnException {
-    int idx = componentInstanceName.lastIndexOf('-');
+    int idx = componentInstanceName.indexOf('.');
+    if (idx != -1) {
+      componentInstanceName = componentInstanceName.substring(0, idx);
+    }
+    idx = componentInstanceName.lastIndexOf('-');
     if (idx == -1) {
       throw new YarnException("Invalid component instance (" +
           componentInstanceName + ") name.");

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/main/proto/ClientAMProtocol.proto

@@ -36,6 +36,8 @@ service ClientAMProtocolService {
     (CompInstancesUpgradeResponseProto);
   rpc getCompInstances(GetCompInstancesRequestProto) returns
     (GetCompInstancesResponseProto);
+  rpc decommissionCompInstances(DecommissionCompInstancesRequestProto)
+    returns (DecommissionCompInstancesResponseProto);
 }
 
 message FlexComponentsRequestProto {
@@ -102,4 +104,11 @@ message GetCompInstancesRequestProto {
 
 message GetCompInstancesResponseProto {
   optional string compInstances = 1;
-}
+}
+
+message DecommissionCompInstancesRequestProto {
+  repeated string compInstances = 1;
+}
+
+message DecommissionCompInstancesResponseProto {
+}

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/test/java/org/apache/hadoop/yarn/service/ServiceTestUtils.java

@@ -246,7 +246,7 @@ public class ServiceTestUtils {
 
     if (yarnCluster == null) {
       yarnCluster =
-          new MiniYARNCluster(TestYarnNativeServices.class.getSimpleName(), 1,
+          new MiniYARNCluster(this.getClass().getSimpleName(), 1,
               numNodeManager, 1, 1);
       yarnCluster.init(conf);
       yarnCluster.start();

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/hadoop-yarn-services-core/src/test/java/org/apache/hadoop/yarn/service/component/TestComponentDecommissionInstances.java

@@ -0,0 +1,147 @@
+/**
+ * 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
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.hadoop.yarn.service.component;
+
+import org.apache.commons.io.FileUtils;
+import org.apache.hadoop.registry.client.binding.RegistryUtils;
+import org.apache.hadoop.test.GenericTestUtils;
+import org.apache.hadoop.yarn.exceptions.YarnException;
+import org.apache.hadoop.yarn.service.ServiceTestUtils;
+import org.apache.hadoop.yarn.service.api.records.Component;
+import org.apache.hadoop.yarn.service.api.records.Container;
+import org.apache.hadoop.yarn.service.api.records.Service;
+import org.apache.hadoop.yarn.service.api.records.ServiceState;
+import org.apache.hadoop.yarn.service.client.ServiceClient;
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.TimeoutException;
+
+/**
+ * Test decommissioning component instances.
+ */
+public class TestComponentDecommissionInstances extends ServiceTestUtils {
+  private static final Logger LOG =
+      LoggerFactory.getLogger(TestComponentDecommissionInstances.class);
+
+  private static final String APP_NAME = "test-decommission";
+  private static final String COMPA = "compa";
+
+  @Rule
+  public TemporaryFolder tmpFolder = new TemporaryFolder();
+
+  @Before
+  public void setup() throws Exception {
+    File tmpYarnDir = new File("target", "tmp");
+    FileUtils.deleteQuietly(tmpYarnDir);
+  }
+
+  @After
+  public void tearDown() throws IOException {
+    shutdown();
+  }
+
+  @Test
+  public void testDecommissionInstances() throws Exception {
+    setupInternal(3);
+    ServiceClient client = createClient(getConf());
+    Service exampleApp = new Service();
+    exampleApp.setName(APP_NAME);
+    exampleApp.setVersion("v1");
+    Component comp = createComponent(COMPA, 6L, "sleep 1000");
+    exampleApp.addComponent(comp);
+    client.actionCreate(exampleApp);
+    waitForServiceToBeStable(client, exampleApp);
+
+    checkInstances(client, COMPA + "-0", COMPA + "-1", COMPA + "-2",
+        COMPA + "-3", COMPA + "-4", COMPA + "-5");
+    client.actionDecommissionInstances(APP_NAME, Arrays.asList(COMPA + "-1",
+        COMPA + "-5"));
+    waitForNumInstances(client, 4);
+    checkInstances(client, COMPA + "-0", COMPA + "-2", COMPA + "-3",
+        COMPA + "-4");
+
+    // Stop and start service
+    client.actionStop(APP_NAME);
+    waitForServiceToBeInState(client, exampleApp, ServiceState.STOPPED);
+    client.actionStart(APP_NAME);
+    waitForServiceToBeStable(client, exampleApp);
+    checkInstances(client, COMPA + "-0", COMPA + "-2", COMPA + "-3",
+        COMPA + "-4");
+
+    Map<String, String> compCounts = new HashMap<>();
+    compCounts.put(COMPA, "5");
+    client.actionFlex(APP_NAME, compCounts);
+    waitForNumInstances(client, 5);
+    checkInstances(client, COMPA + "-0", COMPA + "-2", COMPA + "-3",
+        COMPA + "-4", COMPA + "-6");
+
+    client.actionDecommissionInstances(APP_NAME, Arrays.asList(COMPA + "-0."
+            + APP_NAME + "." + RegistryUtils.currentUser()));
+    waitForNumInstances(client, 4);
+    checkInstances(client, COMPA + "-2", COMPA + "-3",
+        COMPA + "-4", COMPA + "-6");
+  }
+
+  private static void waitForNumInstances(ServiceClient client, int
+      expectedInstances) throws TimeoutException, InterruptedException {
+    GenericTestUtils.waitFor(() -> {
+      try {
+        Service retrievedApp = client.getStatus(APP_NAME);
+        return retrievedApp.getComponent(COMPA).getContainers().size() ==
+            expectedInstances && retrievedApp.getState() == ServiceState.STABLE;
+      } catch (Exception e) {
+        e.printStackTrace();
+        return false;
+      }
+    }, 2000, 200000);
+  }
+
+  private static void checkInstances(ServiceClient client, String... instances)
+      throws IOException, YarnException {
+    Service service = client.getStatus(APP_NAME);
+    Component component = service.getComponent(COMPA);
+    Assert.assertEquals("Service state should be STABLE", ServiceState.STABLE,
+        service.getState());
+    Assert.assertEquals(instances.length + " containers are expected to be " +
+        "running", instances.length, component.getContainers().size());
+    Set<String> existingInstances = new HashSet<>();
+    for (Container cont : component.getContainers()) {
+      existingInstances.add(cont.getComponentInstanceName());
+    }
+    Assert.assertEquals(instances.length + " instances are expected to be " +
+        "running", instances.length, existingInstances.size());
+    for (String instance : instances) {
+      Assert.assertTrue("Expected instance did not exist " + instance,
+          existingInstances.contains(instance));
+    }
+  }
+}

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-client/src/main/java/org/apache/hadoop/yarn/client/cli/ApplicationCLI.java

@@ -99,6 +99,7 @@ public class ApplicationCLI extends YarnCLI {
   public static final String DESTROY_CMD = "destroy";
   public static final String FLEX_CMD = "flex";
   public static final String COMPONENT = "component";
+  public static final String DECOMMISSION = "decommission";
   public static final String ENABLE_FAST_LAUNCH = "enableFastLaunch";
   public static final String UPGRADE_CMD = "upgrade";
   public static final String UPGRADE_EXPRESS = "express";
@@ -239,6 +240,10 @@ public class ApplicationCLI extends YarnCLI {
           "yarn-service. If ID is provided, the appType will be looked up. " +
           "Supports -appTypes option to specify which client implementation " +
           "to use.");
+      opts.addOption(DECOMMISSION, true, "Decommissions component " +
+          "instances for an application / long-running service. Requires " +
+          "-instances option. Supports -appTypes option to specify which " +
+          "client implementation to use.");
       opts.addOption(COMPONENT, true, "Works with -flex option to change " +
           "the number of components/containers running for an application / " +
           "long-running service. Supports absolute or relative changes, such " +
@@ -258,9 +263,12 @@ public class ApplicationCLI extends YarnCLI {
           "application specification file.");
       opts.addOption(COMPONENT_INSTS, true, "Works with -upgrade option to " +
           "trigger the upgrade of specified component instances of the " +
-          "application.");
+          "application. Also works with -decommission option to decommission " +
+          "specified component instances. Multiple instances should be " +
+          "separated by commas.");
       opts.addOption(COMPONENTS, true, "Works with -upgrade option to " +
-          "trigger the upgrade of specified components of the application.");
+          "trigger the upgrade of specified components of the application. " +
+          "Multiple components should be separated by commas.");
       opts.addOption(UPGRADE_FINALIZE, false, "Works with -upgrade option to " +
           "finalize the upgrade.");
       opts.addOption(UPGRADE_AUTO_FINALIZE, false, "Works with -upgrade and " +
@@ -290,6 +298,8 @@ public class ApplicationCLI extends YarnCLI {
       opts.getOption(COMPONENTS).setArgName("Components");
       opts.getOption(COMPONENTS).setValueSeparator(',');
       opts.getOption(COMPONENTS).setArgs(Option.UNLIMITED_VALUES);
+      opts.getOption(DECOMMISSION).setArgName("Application Name");
+      opts.getOption(DECOMMISSION).setArgs(1);
     } else if (title != null && title.equalsIgnoreCase(APPLICATION_ATTEMPT)) {
       opts.addOption(STATUS_CMD, true,
           "Prints the status of the application attempt.");
@@ -708,6 +718,18 @@ public class ApplicationCLI extends YarnCLI {
         }
         return client.actionCancelUpgrade(appName);
       }
+    } else if (cliParser.hasOption(DECOMMISSION)) {
+      if (!cliParser.hasOption(COMPONENT_INSTS) ||
+          hasAnyOtherCLIOptions(cliParser, opts, DECOMMISSION, COMPONENT_INSTS,
+              APP_TYPE_CMD)) {
+        printUsage(title, opts);
+        return exitCode;
+      }
+      String[] instances = cliParser.getOptionValues(COMPONENT_INSTS);
+      String[] appNameAndType = getAppNameAndType(cliParser, DECOMMISSION);
+      return AppAdminClient.createAppAdminClient(appNameAndType[1], getConf())
+          .actionDecommissionInstances(appNameAndType[0],
+              Arrays.asList(instances));
     } else {
       syserr.println("Invalid Command Usage : ");
       printUsage(title, opts);

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-client/src/test/java/org/apache/hadoop/yarn/client/cli/TestYarnCLI.java

@@ -2162,6 +2162,15 @@ public class TestYarnCLI {
     pw.println(" -components <Components>                 Works with -upgrade option to");
     pw.println("                                          trigger the upgrade of specified");
     pw.println("                                          components of the application.");
+    pw.println("                                          Multiple components should be");
+    pw.println("                                          separated by commas.");
+    pw.println(" -decommission <Application Name>         Decommissions component");
+    pw.println("                                          instances for an application /");
+    pw.println("                                          long-running service. Requires");
+    pw.println("                                          -instances option. Supports");
+    pw.println("                                          -appTypes option to specify");
+    pw.println("                                          which client implementation to");
+    pw.println("                                          use.");
     pw.println(" -destroy <Application Name>              Destroys a saved application");
     pw.println("                                          specification and removes all");
     pw.println("                                          application data permanently.");
@@ -2203,7 +2212,11 @@ public class TestYarnCLI {
     pw.println(" -instances <Component Instances>         Works with -upgrade option to");
     pw.println("                                          trigger the upgrade of specified");
     pw.println("                                          component instances of the");
-    pw.println("                                          application.");
+    pw.println("                                          application. Also works with");
+    pw.println("                                          -decommission option to");
+    pw.println("                                          decommission specified component");
+    pw.println("                                          instances. Multiple instances");
+    pw.println("                                          should be separated by commas.");
     pw.println(" -kill <Application ID>                   Kills the application. Set of");
     pw.println("                                          applications can be provided");
     pw.println("                                          separated with space");

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/client/api/AppAdminClient.java

@@ -313,4 +313,16 @@ public abstract class AppAdminClient extends CompositeService {
   @Unstable
   public abstract int actionCancelUpgrade(String appName) throws IOException,
       YarnException;
+
+  /**
+   * Decommission component instances of a long running service.
+   *
+   * @param appName            the name of the application.
+   * @param componentInstances the name of the component instances.
+   */
+  @Public
+  @Unstable
+  public abstract int actionDecommissionInstances(String appName,
+      List<String> componentInstances) throws IOException, YarnException;
+
 }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/YarnCommands.md

@@ -50,10 +50,13 @@ Usage: `yarn app [options] `
 | -appTypes \<Types\> | Works with -list to filter applications based on input comma-separated list of application types. |
 | -changeQueue \<Queue Name\> | Moves application to a new queue. ApplicationId can be passed using 'appId' option. 'movetoqueue' command is deprecated, this new command 'changeQueue' performs same functionality. |
 | -component \<Component Name\> \<Count\> | Works with -flex option to change the number of components/containers running for an application / long-running service. Supports absolute or relative changes, such as +1, 2, or -3. |
+| -components \<Components\> | Works with -upgrade option to trigger the upgrade of specified components of the application. Multiple components should be separated by commas. |
+| -decommission \<Application Name\> | Decommissions component instances for an application / long-running service. Requires -instances option. Supports -appTypes option to specify which client implementation to use. |
 | -destroy \<Application Name\> | Destroys a saved application specification and removes all application data permanently. Supports -appTypes option to specify which client implementation to use. |
 | -enableFastLaunch | Uploads AM dependencies to HDFS to make future launches faster. Supports -appTypes option to specify which client implementation to use. |
 | -flex \<Application Name or ID\> | Changes number of running containers for a component of an application / long-running service. Requires -component option. If name is provided, appType must be provided unless it is the default yarn-service. If ID is provided, the appType will be looked up. Supports -appTypes option to specify which client implementation to use. |
 | -help | Displays help for all commands. |
+| -instances \<Component Instances\> | Works with -upgrade option to trigger the upgrade of specified component instances of the application. Also works with -decommission option to decommission specified component instances. Multiple instances should be separated by commas. |
 | -kill \<Application ID\> | Kills the application. Set of applications can be provided separated with space |
 | -launch \<Application Name\> \<File Name\> | Launches application from specification file (saves specification and starts application). Options -updateLifetime and -changeQueue can be specified to alter the values provided in the file. Supports -appTypes option to specify which client implementation to use. |
 | -list | List applications. Supports optional use of -appTypes to filter applications based on application type, -appStates to filter applications based on application state and -appTags to filter applications based on application tag. |

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/yarn-service/YarnServiceAPI.md

@@ -228,6 +228,7 @@ One or more components of the service. If the service is HBase say, then the com
 |launch_command|The custom launch command of this component (optional for DOCKER component, required otherwise). When specified at the component level, it overrides the value specified at the global level (if any). If docker image supports ENTRYPOINT, launch_command is delimited by comma(,) instead of space.|false|string||
 |resource|Resource of this component (optional). If not specified, the service level global resource takes effect.|false|Resource||
 |number_of_containers|Number of containers for this component (optional). If not specified, the service level global number_of_containers takes effect.|false|integer (int64)||
+|decommissioned_instances|List of decommissioned component instances.|false|string array||
 |containers|Containers of a started component. Specifying a value for this attribute for the POST payload raises a validation error. This blob is available only in the GET response of a started service.|false|Container array||
 |run_privileged_container|Run all containers of this component in privileged mode (YARN-4262).|false|boolean||
 |placement_policy|Advanced scheduling and placement policies for all containers of this component.|false|PlacementPolicy||