HDDS-8166. [Snapshot] Add a config to enable or disable Ozone snapshot feature on OM

hadoop-hdds/common/src/main/resources/ozone-default.xml

@@ -3200,6 +3200,16 @@
     </description>
   </property>
 
+  <property>
+    <name>ozone.filesystem.snapshot.enabled</name>
+    <value>true</value>
+    <tag>OZONE, OM</tag>
+    <description>
+      Enables Ozone filesystem snapshot feature if set to true on the OM side.
+      Disables it otherwise.
+    </description>
+  </property>
+
   <property>
     <name>ozone.snapshot.deleting.service.timeout</name>
     <value>300s</value>

hadoop-ozone/common/src/main/java/org/apache/hadoop/ozone/om/OMConfigKeys.java

@@ -45,6 +45,10 @@ public final class OMConfigKeys {
   private OMConfigKeys() {
   }
 
+  public static final String OZONE_FILESYSTEM_SNAPSHOT_ENABLED_KEY =
+      "ozone.filesystem.snapshot.enabled";
+  public static final boolean OZONE_FILESYSTEM_SNAPSHOT_ENABLED_DEFAULT = true;
+
   // Location where the OM stores its DB files. In the future we may support
   // multiple entries for performance (sharding)..
   public static final String OZONE_OM_DB_DIRS = "ozone.om.db.dirs";

hadoop-ozone/dist/src/main/compose/ozone/docker-config

@@ -53,3 +53,6 @@ OZONE_CONF_DIR=/etc/hadoop
 OZONE_LOG_DIR=/var/log/hadoop
 
 no_proxy=om,scm,s3g,recon,kdc,localhost,127.0.0.1
+
+# Explicitly enable filesystem snapshot feature for this Docker compose cluster
+OZONE-SITE.XML_ozone.filesystem.snapshot.enabled=true

hadoop-ozone/dist/src/main/compose/ozonesecure/docker-config

@@ -182,3 +182,6 @@ OZONE-SITE.XML_ozone.om.multitenancy.ranger.sync.timeout=10s
 # change or let all OMs write to AccessController if this dev flag is set.
 #
 OZONE-SITE.XML_ozone.om.tenant.dev.skip.ranger=true
+
+# Explicitly enable filesystem snapshot feature for this Docker compose cluster
+OZONE-SITE.XML_ozone.filesystem.snapshot.enabled=true

hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/KeyManagerImpl.java

@@ -272,7 +272,9 @@ public void start(OzoneConfiguration configuration) {
       }
     }
 
-    if (snapshotDeletingService == null) {
+    if (snapshotDeletingService == null &&
+        ozoneManager.isFilesystemSnapshotEnabled()) {
+
       long snapshotServiceInterval = configuration.getTimeDuration(
           OZONE_SNAPSHOT_DELETING_SERVICE_INTERVAL,
           OZONE_SNAPSHOT_DELETING_SERVICE_INTERVAL_DEFAULT,

hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/OzoneManager.java

@@ -434,6 +434,8 @@ public final class OzoneManager extends ServiceRuntimeInfoImpl
   private final OzoneLockProvider ozoneLockProvider;
   private OMPerformanceMetrics perfMetrics;
 
+  private boolean fsSnapshotEnabled;
+
   /**
    * OM Startup mode.
    */
@@ -544,6 +546,10 @@ private OzoneManager(OzoneConfiguration conf, StartupOption startupOption)
         OMConfigKeys.OZONE_OM_RATIS_ENABLE_KEY,
         OMConfigKeys.OZONE_OM_RATIS_ENABLE_DEFAULT);
 
+    fsSnapshotEnabled = configuration.getBoolean(
+        OMConfigKeys.OZONE_FILESYSTEM_SNAPSHOT_ENABLED_KEY,
+        OMConfigKeys.OZONE_FILESYSTEM_SNAPSHOT_ENABLED_DEFAULT);
+
     String defaultBucketLayoutString =
         configuration.getTrimmed(OZONE_DEFAULT_BUCKET_LAYOUT,
             OZONE_DEFAULT_BUCKET_LAYOUT_DEFAULT);
@@ -783,7 +789,13 @@ private void instantiateServices(boolean withNewSnapshot) throws IOException {
         perfMetrics);
     omMetadataReader = new OmMetadataReader(keyManager, prefixManager,
         this, LOG, AUDIT, metrics);
-    omSnapshotManager = new OmSnapshotManager(this);
+
+    if (fsSnapshotEnabled) {
+      omSnapshotManager = new OmSnapshotManager(this);
+    } else {
+      omSnapshotManager = null;
+      // TODO: [Snapshot] Check all usages of omSnapshotManager.
+    }
 
     // Snapshot metrics
     updateActiveSnapshotMetrics();
@@ -3994,6 +4006,13 @@ public boolean isRatisEnabled() {
     return isRatisEnabled;
   }
 
+  /**
+   * @return true if Ozone filesystem snapshot is enabled, false otherwise.
+   */
+  public boolean isFilesystemSnapshotEnabled() {
+    return fsSnapshotEnabled;
+  }
+
   /**
    * Get DB updates since a specific sequence number.
    *

hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/request/OMClientRequest.java

@@ -54,6 +54,7 @@
 import java.util.LinkedHashMap;
 import java.util.Map;
 
+import static org.apache.hadoop.ozone.om.exceptions.OMException.ResultCodes.FEATURE_NOT_ENABLED;
 import static org.apache.hadoop.ozone.om.exceptions.OMException.ResultCodes.INVALID_KEY_NAME;
 
 /**
@@ -569,4 +570,15 @@ public static String isValidKeyPath(String path) throws OMException {
       throw new OMException("Invalid KeyPath " + path, INVALID_KEY_NAME);
     }
   }
+
+  /**
+   * Helper method that throws OMException if filesystem snapshot is disabled.
+   */
+  protected static void checkFsSnapshotEnabled(OzoneManager ozoneManager)
+      throws OMException {
+    if (!ozoneManager.isFilesystemSnapshotEnabled()) {
+      throw new OMException("Snapshot is not enabled", FEATURE_NOT_ENABLED);
+    }
+  }
+
 }

hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/request/snapshot/OMSnapshotCreateRequest.java

@@ -88,6 +88,11 @@ public OMSnapshotCreateRequest(OMRequest omRequest) {
 
   @Override
   public OMRequest preExecute(OzoneManager ozoneManager) throws IOException {
+    // Reject if snapshot feature is disabled
+    checkFsSnapshotEnabled(ozoneManager);
+    // TODO: Use an annotation similar to @DisallowedUntilLayoutVersion instead?
+    //  See HDDS-7772.
+
     final OMRequest omRequest = super.preExecute(ozoneManager);
     // Verify name
     OmUtils.validateSnapshotName(snapshotName);

hadoop-ozone/ozone-manager/src/test/java/org/apache/hadoop/ozone/om/service/TestSnapshotDeletingService.java

@@ -25,6 +25,7 @@
 import org.apache.hadoop.hdds.server.ServerUtils;
 import org.apache.hadoop.hdds.utils.db.DBConfigFromFile;
 import org.apache.hadoop.ozone.om.KeyManager;
+import org.apache.hadoop.ozone.om.OMConfigKeys;
 import org.apache.hadoop.ozone.om.OMMetadataManager;
 import org.apache.hadoop.ozone.om.OmSnapshot;
 import org.apache.hadoop.ozone.om.OmTestManagers;
@@ -94,6 +95,8 @@ public void createConfAndInitValues() throws Exception {
     conf.setTimeDuration(OZONE_SNAPSHOT_DELETING_SERVICE_TIMEOUT,
         100000, TimeUnit.MILLISECONDS);
     conf.setQuietMode(false);
+    // Enable filesystem snapshot feature for the test regardless of the default
+    conf.setBoolean(OMConfigKeys.OZONE_FILESYSTEM_SNAPSHOT_ENABLED_KEY, true);
     omTestManagers = new OmTestManagers(conf);
     keyManager = omTestManagers.getKeyManager();
     omMetadataManager = omTestManagers.getMetadataManager();