MS maintenance improvements

agent/src/main/java/com/cloud/agent/Agent.java

@@ -342,7 +342,7 @@
                 logger.info("Attempted to connect to the server, but received an unexpected exception, trying again...", e);
             }
         }
-        shell.updateConnectedHost();
+        shell.updateConnectedHost(((NioClient)connection).getHost());
         scavengeOldAgentObjects();
     }
 
@@ -617,15 +617,11 @@
     }
 
     protected void reconnect(final Link link) {
-        reconnect(link, null, null, false);
+        reconnect(link, null, false);
     }
 
-    protected void reconnect(final Link link, String preferredHost, List<String> avoidHostList, boolean forTransfer) {
+    protected void reconnect(final Link link, String preferredMSHost, boolean forTransfer) {
         if (!(forTransfer || reconnectAllowed)) {
-            return;
-        }
-
-        if (!reconnectAllowed) {
             logger.debug("Reconnect requested but it is not allowed {}", () -> getLinkLog(link));
             return;
         }
@@ -637,19 +633,26 @@
         serverResource.disconnected();
         logger.info("Lost connection to host: {}. Attempting reconnection while we still have {} commands in progress.", shell.getConnectedHost(), commandsInProgress.get());
         stopAndCleanupConnection(true);
+        String host = preferredMSHost;
+        if (org.apache.commons.lang3.StringUtils.isBlank(host)) {
+            host = shell.getNextHost();
+        }
+        List<String> avoidMSHostList = shell.getAvoidHosts();
         do {
-            final String host = shell.getNextHost();
-            connection = new NioClient(getAgentName(), host, shell.getPort(), shell.getWorkers(), shell.getSslHandshakeTimeout(), this);
-            logger.info("Reconnecting to host: {}", host);
-            try {
-                connection.start();
-            } catch (final NioConnectionException e) {
-                logger.info("Attempted to re-connect to the server, but received an unexpected exception, trying again...", e);
-                stopAndCleanupConnection(false);
+            if (CollectionUtils.isEmpty(avoidMSHostList) || !avoidMSHostList.contains(host)) {
+                connection = new NioClient(getAgentName(), host, shell.getPort(), shell.getWorkers(), shell.getSslHandshakeTimeout(), this);
+                logger.info("Reconnecting to host: {}", host);
+                try {
+                    connection.start();
+                } catch (final NioConnectionException e) {
+                    logger.info("Attempted to re-connect to the server, but received an unexpected exception, trying again...", e);
+                    stopAndCleanupConnection(false);
+                }
             }
             shell.getBackoffAlgorithm().waitBeforeRetry();
+            host = shell.getNextHost();
         } while (!connection.isStartup());
-        shell.updateConnectedHost();
+        shell.updateConnectedHost(((NioClient)connection).getHost());
         logger.info("Connected to the host: {}", shell.getConnectedHost());
     }
 
@@ -922,7 +925,7 @@
         return new SetupCertificateAnswer(true);
     }
 
-    private void processManagementServerList(final List<String> msList, final String lbAlgorithm, final Long lbCheckInterval) {
+    private void processManagementServerList(final List<String> msList, final List<String> avoidMsList, final String lbAlgorithm, final Long lbCheckInterval) {
         if (CollectionUtils.isNotEmpty(msList) && StringUtils.isNotEmpty(lbAlgorithm)) {
             try {
                 final String newMSHosts = String.format("%s%s%s", com.cloud.utils.StringUtils.toCSVList(msList), IAgentShell.hostLbAlgorithmSeparator, lbAlgorithm);
@@ -934,6 +937,7 @@
                 throw new CloudRuntimeException("Could not persist received management servers list", e);
             }
         }
+        shell.setAvoidHosts(avoidMsList);
         if ("shuffle".equals(lbAlgorithm)) {
             scheduleHostLBCheckerTask(0);
         } else {
@@ -942,16 +946,18 @@
     }
 
     private Answer setupManagementServerList(final SetupMSListCommand cmd) {
-        processManagementServerList(cmd.getMsList(), cmd.getLbAlgorithm(), cmd.getLbCheckInterval());
+        processManagementServerList(cmd.getMsList(), cmd.getAvoidMsList(), cmd.getLbAlgorithm(), cmd.getLbCheckInterval());
         return new SetupMSListAnswer(true);
     }
 
     private Answer migrateAgentToOtherMS(final MigrateAgentConnectionCommand cmd) {
         try {
             if (CollectionUtils.isNotEmpty(cmd.getMsList())) {
-                processManagementServerList(cmd.getMsList(), cmd.getLbAlgorithm(), cmd.getLbCheckInterval());
+                processManagementServerList(cmd.getMsList(), cmd.getAvoidMsList(), cmd.getLbAlgorithm(), cmd.getLbCheckInterval());
             }
-            migrateAgentConnection(cmd.getAvoidMsList());
+            Executors.newSingleThreadScheduledExecutor(new NamedThreadFactory("MigrateAgentConnection-Job")).schedule(() -> {
+                migrateAgentConnection(cmd.getAvoidMsList());
+            }, 3, TimeUnit.SECONDS);
         } catch (Exception e) {
             String errMsg = "Migrate agent connection failed, due to " + e.getMessage();
             logger.debug(errMsg, e);
@@ -972,25 +978,26 @@
             throw new CloudRuntimeException("No other Management Server hosts to migrate");
         }
 
-        String preferredHost  = null;
+        String preferredMSHost  = null;
         for (String msHost : msHostsList) {
             try (final Socket socket = new Socket()) {
                 socket.connect(new InetSocketAddress(msHost, shell.getPort()), 5000);
-                preferredHost = msHost;
+                preferredMSHost = msHost;
                 break;
             } catch (final IOException e) {
                 throw new CloudRuntimeException("Management server host: " + msHost + " is not reachable, to migrate connection");
             }
         }
 
-        if (preferredHost == null) {
+        if (preferredMSHost == null) {
             throw new CloudRuntimeException("Management server host(s) are not reachable, to migrate connection");
         }
 
-        logger.debug("Management server host " + preferredHost + " is found to be reachable, trying to reconnect");
+        logger.debug("Management server host " + preferredMSHost + " is found to be reachable, trying to reconnect");
         shell.resetHostCounter();
+        shell.setAvoidHosts(avoidMsList);
         shell.setConnectionTransfer(true);
-        reconnect(link, preferredHost, avoidMsList, true);
+        reconnect(link, preferredMSHost, true);
     }
 
     public void processResponse(final Response response, final Link link) {
@@ -1003,14 +1010,21 @@
             for (final IAgentControlListener listener : controlListeners) {
                 listener.processControlResponse(response, (AgentControlAnswer)answer);
             }
-        } else if (answer instanceof PingAnswer && (((PingAnswer) answer).isSendStartup()) && reconnectAllowed) {
-            logger.info("Management server requested startup command to reinitialize the agent");
-            sendStartup(link);
+        } else if (answer instanceof PingAnswer) {
+            processPingAnswer((PingAnswer) answer);
         } else {
             updateLastPingResponseTime();
         }
     }
 
+    private void processPingAnswer(final PingAnswer answer) {
+        if ((answer.isSendStartup()) && reconnectAllowed) {
+            logger.info("Management server requested startup command to reinitialize the agent");
+            sendStartup(link);
+        }
+        shell.setAvoidHosts(answer.getAvoidMsList());
+    }
+
     public void processReadyCommand(final Command cmd) {
         final ReadyCommand ready = (ReadyCommand)cmd;
         // Set human readable sizes;
@@ -1027,7 +1041,7 @@
         }
 
         verifyAgentArch(ready.getArch());
-        processManagementServerList(ready.getMsHostList(), ready.getLbAlgorithm(), ready.getLbCheckInterval());
+        processManagementServerList(ready.getMsHostList(), ready.getAvoidMsHostList(), ready.getLbAlgorithm(), ready.getLbCheckInterval());
 
         logger.info("Ready command is processed for agent [id: {}, uuid: {}, name: {}]", getId(), getUuid(), getName());
     }
@@ -1374,26 +1388,26 @@
                 if (msList == null || msList.length < 1) {
                     return;
                 }
-                final String preferredHost  = msList[0];
+                final String preferredMSHost  = msList[0];
                 final String connectedHost = shell.getConnectedHost();
                 logger.debug("Running preferred host checker task, connected host={}, preferred host={}",
-                        connectedHost, preferredHost);
-                if (preferredHost == null || preferredHost.equals(connectedHost) || link == null) {
+                        connectedHost, preferredMSHost);
+                if (preferredMSHost == null || preferredMSHost.equals(connectedHost) || link == null) {
                     return;
                 }
                 boolean isHostUp = false;
                 try (final Socket socket = new Socket()) {
-                    socket.connect(new InetSocketAddress(preferredHost, shell.getPort()), 5000);
+                    socket.connect(new InetSocketAddress(preferredMSHost, shell.getPort()), 5000);
                     isHostUp = true;
                 } catch (final IOException e) {
-                    logger.debug("Host: {} is not reachable", preferredHost);
+                    logger.debug("Host: {} is not reachable", preferredMSHost);
                 }
                 if (isHostUp && link != null && commandsInProgress.get() == 0) {
                     if (logger.isDebugEnabled()) {
-                        logger.debug("Preferred host {} is found to be reachable, trying to reconnect", preferredHost);
+                        logger.debug("Preferred host {} is found to be reachable, trying to reconnect", preferredMSHost);
                     }
                     shell.resetHostCounter();
-                    reconnect(link);
+                    reconnect(link, preferredMSHost, false);
                 }
             } catch (Throwable t) {
                 logger.error("Error caught while attempting to connect to preferred host", t);

agent/src/main/java/com/cloud/agent/AgentShell.java

@@ -66,6 +66,7 @@
     private String _zone;
     private String _pod;
     private String _host;
+    private List<String> _avoidHosts;
     private String _privateIp;
     private int _port;
     private int _proxyPort;
@@ -76,7 +77,6 @@
     private volatile boolean _exit = false;
     private int _pingRetries;
     private final List<Agent> _agents = new ArrayList<Agent>();
-    private String hostToConnect;
     private String connectedHost;
     private Long preferredHostCheckInterval;
     private boolean connectionTransfer = false;
@@ -121,7 +121,7 @@
         if (_hostCounter >= hosts.length) {
             _hostCounter = 0;
         }
-        hostToConnect = hosts[_hostCounter % hosts.length];
+        String hostToConnect = hosts[_hostCounter % hosts.length];
         _hostCounter++;
         return hostToConnect;
     }
@@ -143,11 +143,10 @@
     }
 
     @Override
-    public void updateConnectedHost() {
-        connectedHost = hostToConnect;
+    public void updateConnectedHost(String connectedHost) {
+        this.connectedHost = connectedHost;
     }
 
-
     @Override
     public void resetHostCounter() {
         _hostCounter = 0;
@@ -166,6 +165,16 @@
         }
     }
 
+    @Override
+    public void setAvoidHosts(List<String> avoidHosts) {
+        _avoidHosts = avoidHosts;
+    }
+
+    @Override
+    public List<String> getAvoidHosts() {
+        return _avoidHosts;
+    }
+
     @Override
     public String getPrivateIp() {
         return _privateIp;

agent/src/main/java/com/cloud/agent/IAgentShell.java

@@ -16,6 +16,7 @@
 // under the License.
 package com.cloud.agent;
 
+import java.util.List;
 import java.util.Map;
 import java.util.Properties;
 
@@ -63,9 +64,13 @@ public interface IAgentShell {
 
     String[] getHosts();
 
+    void setAvoidHosts(List<String> hosts);
+
+    List<String> getAvoidHosts();
+
     long getLbCheckerInterval(Long receivedLbInterval);
 
-    void updateConnectedHost();
+    void updateConnectedHost(String connectedHost);
 
     String getConnectedHost();
 

agent/src/main/java/com/cloud/agent/properties/AgentProperties.java

@@ -816,7 +816,7 @@ public Property<Integer> getWorkers() {
      * Data type: Integer.<br>
      * Default value: <code>null</code>
      */
-    public static final Property<Integer> SSL_HANDSHAKE_TIMEOUT = new Property<>("ssl.handshake.timeout", null, Integer.class);
+    public static final Property<Integer> SSL_HANDSHAKE_TIMEOUT = new Property<>("ssl.handshake.timeout", 30, Integer.class);
 
     public static class Property <T>{
         private String name;

agent/src/test/java/com/cloud/agent/AgentShellTest.java

@@ -358,7 +358,7 @@ public void updateAndGetConnectedHost() {
         AgentShell shell = new AgentShell();
         shell.setHosts("test");
         shell.getNextHost();
-        shell.updateConnectedHost();
+        shell.updateConnectedHost("test");
 
         Assert.assertEquals(expected, shell.getConnectedHost());
     }

api/src/main/java/com/cloud/event/EventTypes.java

@@ -739,6 +739,13 @@ public class EventTypes {
     //Purge resources
     public static final String EVENT_PURGE_EXPUNGED_RESOURCES = "PURGE.EXPUNGED.RESOURCES";
 
+    // Management Server
+    public static final String EVENT_MS_MAINTENANCE_PREPARE = "MS.MAINTENANCE.PREPARE";
+    public static final String EVENT_MS_MAINTENANCE_CANCEL = "MS.MAINTENANCE.CANCEL";
+    public static final String EVENT_MS_SHUTDOWN_PREPARE = "MS.SHUTDOWN.PREPARE";
+    public static final String EVENT_MS_SHUTDOWN_CANCEL = "MS.SHUTDOWN.CANCEL";
+    public static final String EVENT_MS_SHUTDOWN = "MS.SHUTDOWN";
+
     // OBJECT STORE
     public static final String EVENT_OBJECT_STORE_CREATE = "OBJECT.STORE.CREATE";
     public static final String EVENT_OBJECT_STORE_DELETE = "OBJECT.STORE.DELETE";
@@ -1233,6 +1240,12 @@ public class EventTypes {
         entityEventDetails.put(EVENT_UPDATE_IMAGE_STORE_ACCESS_STATE, ImageStore.class);
         entityEventDetails.put(EVENT_LIVE_PATCH_SYSTEMVM, "SystemVMs");
 
+        entityEventDetails.put(EVENT_MS_MAINTENANCE_PREPARE, "ManagementServer");
+        entityEventDetails.put(EVENT_MS_MAINTENANCE_CANCEL, "ManagementServer");
+        entityEventDetails.put(EVENT_MS_SHUTDOWN_PREPARE, "ManagementServer");
+        entityEventDetails.put(EVENT_MS_SHUTDOWN_CANCEL, "ManagementServer");
+        entityEventDetails.put(EVENT_MS_SHUTDOWN, "ManagementServer");
+
         //Object Store
         entityEventDetails.put(EVENT_OBJECT_STORE_CREATE, ObjectStore.class);
         entityEventDetails.put(EVENT_OBJECT_STORE_UPDATE, ObjectStore.class);

api/src/main/java/org/apache/cloudstack/api/ApiConstants.java

@@ -1150,6 +1150,7 @@ public class ApiConstants {
     public static final String PENDING_JOBS_COUNT = "pendingjobscount";
     public static final String AGENTS_COUNT = "agentscount";
     public static final String AGENTS = "agents";
+    public static final String LAST_AGENTS = "lastagents";
 
     public static final String PUBLIC_MTU = "publicmtu";
     public static final String PRIVATE_MTU = "privatemtu";

api/src/main/java/org/apache/cloudstack/api/ApiErrorCode.java

@@ -30,6 +30,7 @@ public enum ApiErrorCode {
     UNSUPPORTED_ACTION_ERROR(432),
     API_LIMIT_EXCEED(429),
 
+    SERVICE_UNAVAILABLE(503),
     INTERNAL_ERROR(530),
     ACCOUNT_ERROR(531),
     ACCOUNT_RESOURCE_LIMIT_ERROR(532),

api/src/main/java/org/apache/cloudstack/api/response/ManagementServerResponse.java

@@ -82,6 +82,14 @@
     @Param(description = "the Management Server Peers")
     private List<PeerManagementServerNodeResponse> peers;
 
+    @SerializedName(ApiConstants.LAST_AGENTS)
+    @Param(description = "the last agents this Management Server is responsible for, before shutdown or preparing for maintenance", since = "4.21.0.0")
+    private List<String> lastAgents;
+
+    @SerializedName(ApiConstants.AGENTS)
+    @Param(description = "the agents this Management Server is responsible for", since = "4.21.0.0")
+    private List<String> agents;
+
     @SerializedName(ApiConstants.AGENTS_COUNT)
     @Param(description = "the number of host agents this Management Server is responsible for", since = "4.21.0.0")
     private Long agentsCount;
@@ -134,6 +142,14 @@
         return ipAddress;
     }
 
+    public List<String> getLastAgents() {
+        return lastAgents;
+    }
+
+    public List<String> getAgents() {
+        return agents;
+    }
+
     public Long getAgentsCount() {
         return this.agentsCount;
     }
@@ -190,6 +206,14 @@
         this.ipAddress = ipAddress;
     }
 
+    public void setLastAgents(List<String> lastAgents) {
+        this.lastAgents = lastAgents;
+    }
+
+    public void setAgents(List<String> agents) {
+        this.agents = agents;
+    }
+
     public void setAgentsCount(Long agentsCount) {
         this.agentsCount = agentsCount;
     }