Service Layer changes for Recommission API

CHANGELOG.md

@@ -27,6 +27,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Add getter for path field in NestedQueryBuilder ([#4636](https://github.com/opensearch-project/OpenSearch/pull/4636))
 - Added precommit support for windows ([#4676](https://github.com/opensearch-project/OpenSearch/pull/4676))
 - Added precommit support for MacOS ([#4682](https://github.com/opensearch-project/OpenSearch/pull/4682))
+- Recommission API changes for service layer ([#4320](https://github.com/opensearch-project/OpenSearch/pull/4320))
 ### Dependencies
 - Bumps `log4j-core` from 2.18.0 to 2.19.0
 - Bumps `reactor-netty-http` from 1.0.18 to 1.0.23

server/src/main/java/org/opensearch/cluster/decommission/DecommissionService.java

@@ -14,6 +14,7 @@
 import org.opensearch.OpenSearchTimeoutException;
 import org.opensearch.action.ActionListener;
 import org.opensearch.action.admin.cluster.decommission.awareness.put.DecommissionResponse;
+import org.opensearch.action.support.master.AcknowledgedResponse;
 import org.opensearch.cluster.ClusterState;
 import org.opensearch.cluster.ClusterStateObserver;
 import org.opensearch.cluster.ClusterStateUpdateTask;
@@ -481,4 +482,53 @@ public void onFailure(Exception e) {
             }
         };
     }
+
+    public void startRecommissionAction(final ActionListener<AcknowledgedResponse> listener) {
+        /*
+         * For abandoned requests, we might not really know if it actually restored the exclusion list.
+         * And can land up in cases where even after recommission, exclusions are set(which is unexpected).
+         * And by definition of OpenSearch - Clusters should have no voting configuration exclusions in normal operation.
+         * Once the excluded nodes have stopped, clear the voting configuration exclusions with DELETE /_cluster/voting_config_exclusions.
+         * And hence it is safe to remove the exclusion if any. User should make conscious choice before decommissioning awareness attribute.
+         */
+        decommissionController.clearVotingConfigExclusion(new ActionListener<Void>() {
+            @Override
+            public void onResponse(Void unused) {
+                logger.info("successfully cleared voting config exclusion for deleting the decommission");
+                deleteDecommissionState(listener);
+            }
+
+            @Override
+            public void onFailure(Exception e) {
+                logger.error(new ParameterizedMessage("failure in clearing voting config during delete_decommission request"), e);
+                listener.onFailure(e);
+            }
+        }, false);
+    }
+
+    void deleteDecommissionState(ActionListener<AcknowledgedResponse> listener) {
+        clusterService.submitStateUpdateTask("delete_decommission_state", new ClusterStateUpdateTask(Priority.URGENT) {
+            @Override
+            public ClusterState execute(ClusterState currentState) {
+                logger.info("Deleting the decommission attribute from cluster state");
+                Metadata metadata = currentState.metadata();
+                Metadata.Builder mdBuilder = Metadata.builder(metadata);
+                mdBuilder.removeCustom(DecommissionAttributeMetadata.TYPE);
+                return ClusterState.builder(currentState).metadata(mdBuilder).build();
+            }
+
+            @Override
+            public void onFailure(String source, Exception e) {
+                logger.error(() -> new ParameterizedMessage("Failed to clear decommission attribute. Exception: [{}]"), e);
+                listener.onFailure(e);
+            }
+
+            @Override
+            public void clusterStateProcessed(String source, ClusterState oldState, ClusterState newState) {
+                // Cluster state Processed for deleting the decommission attribute.
+                assert newState.metadata().decommissionAttributeMetadata() == null;
+                listener.onResponse(new AcknowledgedResponse(true));
+            }
+        });
+    }
 }

server/src/test/java/org/opensearch/cluster/decommission/DecommissionServiceTests.java

@@ -11,9 +11,13 @@
 import org.hamcrest.Matchers;
 import org.junit.After;
 import org.junit.Before;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Mockito;
 import org.opensearch.Version;
 import org.opensearch.action.ActionListener;
 import org.opensearch.action.admin.cluster.decommission.awareness.put.DecommissionResponse;
+import org.opensearch.action.admin.cluster.configuration.ClearVotingConfigExclusionsRequest;
+import org.opensearch.action.support.master.AcknowledgedResponse;
 import org.opensearch.cluster.ClusterName;
 import org.opensearch.cluster.ClusterState;
 import org.opensearch.cluster.coordination.CoordinationMetadata;
@@ -30,6 +34,7 @@
 import org.opensearch.test.transport.MockTransport;
 import org.opensearch.threadpool.TestThreadPool;
 import org.opensearch.threadpool.ThreadPool;
+import org.opensearch.transport.TransportResponseHandler;
 import org.opensearch.transport.TransportService;
 
 import java.util.Collections;
@@ -201,6 +206,86 @@ public void onFailure(Exception e) {
         assertTrue(countDownLatch.await(30, TimeUnit.SECONDS));
     }
 
+    public void testClearClusterDecommissionState() throws InterruptedException {
+        final CountDownLatch countDownLatch = new CountDownLatch(1);
+        DecommissionAttribute decommissionAttribute = new DecommissionAttribute("zone", "zone-2");
+        DecommissionAttributeMetadata decommissionAttributeMetadata = new DecommissionAttributeMetadata(
+            decommissionAttribute,
+            DecommissionStatus.SUCCESSFUL
+        );
+        ClusterState state = ClusterState.builder(new ClusterName("test"))
+            .metadata(Metadata.builder().putCustom(DecommissionAttributeMetadata.TYPE, decommissionAttributeMetadata).build())
+            .build();
+
+        ActionListener<AcknowledgedResponse> listener = new ActionListener<AcknowledgedResponse>() {
+            @Override
+            public void onResponse(AcknowledgedResponse decommissionResponse) {
+                DecommissionAttributeMetadata metadata = clusterService.state().metadata().custom(DecommissionAttributeMetadata.TYPE);
+                assertNull(metadata);
+                countDownLatch.countDown();
+            }
+
+            @Override
+            public void onFailure(Exception e) {
+                fail("on failure shouldn't have been called");
+                countDownLatch.countDown();
+            }
+        };
+
+        this.decommissionService.deleteDecommissionState(listener);
+
+        // Decommission Attribute should be removed.
+        assertTrue(countDownLatch.await(30, TimeUnit.SECONDS));
+    }
+
+    public void testDeleteDecommissionAttributeClearVotingExclusion() {
+        TransportService mockTransportService = Mockito.mock(TransportService.class);
+        Mockito.when(mockTransportService.getLocalNode()).thenReturn(Mockito.mock(DiscoveryNode.class));
+        DecommissionService decommissionService = new DecommissionService(
+            Settings.EMPTY,
+            clusterSettings,
+            clusterService,
+            mockTransportService,
+            threadPool,
+            allocationService
+        );
+        decommissionService.startRecommissionAction(Mockito.mock(ActionListener.class));
+
+        ArgumentCaptor<ClearVotingConfigExclusionsRequest> clearVotingConfigExclusionsRequestArgumentCaptor = ArgumentCaptor.forClass(
+            ClearVotingConfigExclusionsRequest.class
+        );
+        Mockito.verify(mockTransportService)
+            .sendRequest(
+                Mockito.any(DiscoveryNode.class),
+                Mockito.anyString(),
+                clearVotingConfigExclusionsRequestArgumentCaptor.capture(),
+                Mockito.any(TransportResponseHandler.class)
+            );
+
+        ClearVotingConfigExclusionsRequest request = clearVotingConfigExclusionsRequestArgumentCaptor.getValue();
+        assertFalse(request.getWaitForRemoval());
+    }
+
+    public void testClusterUpdateTaskForDeletingDecommission() throws InterruptedException {
+        final CountDownLatch countDownLatch = new CountDownLatch(1);
+        ActionListener<AcknowledgedResponse> listener = new ActionListener<>() {
+            @Override
+            public void onResponse(AcknowledgedResponse response) {
+                assertTrue(response.isAcknowledged());
+                assertNull(clusterService.state().metadata().decommissionAttributeMetadata());
+                countDownLatch.countDown();
+            }
+
+            @Override
+            public void onFailure(Exception e) {
+                fail("On Failure shouldn't have been called");
+                countDownLatch.countDown();
+            }
+        };
+        decommissionService.deleteDecommissionState(listener);
+        assertTrue(countDownLatch.await(30, TimeUnit.SECONDS));
+    }
+
     private ClusterState addDataNodes(ClusterState clusterState, String zone, String... nodeIds) {
         DiscoveryNodes.Builder nodeBuilder = DiscoveryNodes.builder(clusterState.nodes());
         org.opensearch.common.collect.List.of(nodeIds).forEach(nodeId -> nodeBuilder.add(newDataNode(nodeId, singletonMap("zone", zone))));