[ML] Wait for shards to initialize after creating ML internal indices (#59027)

There have been a few test failures that are likely caused by tests
performing actions that use ML indices immediately after the actions
that create those ML indices.  Currently this can result in attempts
to search the newly created index before its shards have initialized.

This change makes the method that creates the internal ML indices
that have been affected by this problem (state and stats) wait for
the shards to be initialized before returning.

Fixes #54887
Fixes #55221
Fixes #55807
Fixes #57102
Fixes #58841
Fixes #59011

Author: droberts195

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/utils/MlIndexAndAlias.java

@@ -9,6 +9,8 @@
 import org.apache.logging.log4j.Logger;
 import org.elasticsearch.ResourceAlreadyExistsException;
 import org.elasticsearch.action.ActionListener;
+import org.elasticsearch.action.admin.cluster.health.ClusterHealthRequest;
+import org.elasticsearch.action.admin.cluster.health.ClusterHealthResponse;
 import org.elasticsearch.action.admin.indices.alias.Alias;
 import org.elasticsearch.action.admin.indices.alias.IndicesAliasesRequest;
 import org.elasticsearch.action.admin.indices.alias.IndicesAliasesRequestBuilder;
@@ -18,6 +20,7 @@
 import org.elasticsearch.action.support.IndicesOptions;
 import org.elasticsearch.action.support.master.AcknowledgedResponse;
 import org.elasticsearch.client.Client;
+import org.elasticsearch.client.Requests;
 import org.elasticsearch.cluster.ClusterState;
 import org.elasticsearch.cluster.metadata.IndexMetadata;
 import org.elasticsearch.cluster.metadata.IndexNameExpressionResolver;
@@ -69,13 +72,27 @@ private MlIndexAndAlias() {}
      * Adds an {@code alias} to that index if it was created,
      * or to the index with the highest suffix if the index did not have to be created.
      * The listener is notified with a {@code boolean} that informs whether the index or the alias were created.
+     * If the index is created, the listener is not called until the index is ready to use via the supplied alias,
+     * so that a method that receives a success response from this method can safely use the index immediately.
      */
     public static void createIndexAndAliasIfNecessary(Client client,
                                                       ClusterState clusterState,
                                                       IndexNameExpressionResolver resolver,
                                                       String indexPatternPrefix,
                                                       String alias,
-                                                      ActionListener<Boolean> listener) {
+                                                      ActionListener<Boolean> finalListener) {
+
+        // If both the index and alias were successfully created then wait for the shards of the index that the alias points to be ready
+        ActionListener<Boolean> indexCreatedListener = ActionListener.wrap(
+            created -> {
+                if (created) {
+                    waitForShardsReady(client, alias, finalListener);
+                } else {
+                    finalListener.onResponse(false);
+                }
+            },
+            finalListener::onFailure
+        );
 
         String legacyIndexWithoutSuffix = indexPatternPrefix;
         String indexPattern = indexPatternPrefix + "*";
@@ -89,15 +106,15 @@ public static void createIndexAndAliasIfNecessary(Client client,
 
         if (concreteIndexNames.length == 0) {
             if (indexPointedByCurrentWriteAlias.isEmpty()) {
-                createFirstConcreteIndex(client, firstConcreteIndex, alias, true, listener);
+                createFirstConcreteIndex(client, firstConcreteIndex, alias, true, indexCreatedListener);
                 return;
             }
             logger.error(
                 "There are no indices matching '{}' pattern but '{}' alias points at [{}]. This should never happen.",
                 indexPattern, alias, indexPointedByCurrentWriteAlias.get());
         } else if (concreteIndexNames.length == 1 && concreteIndexNames[0].equals(legacyIndexWithoutSuffix)) {
             if (indexPointedByCurrentWriteAlias.isEmpty()) {
-                createFirstConcreteIndex(client, firstConcreteIndex, alias, true, listener);
+                createFirstConcreteIndex(client, firstConcreteIndex, alias, true, indexCreatedListener);
                 return;
             }
             if (indexPointedByCurrentWriteAlias.get().getIndex().getName().equals(legacyIndexWithoutSuffix)) {
@@ -107,8 +124,8 @@ public static void createIndexAndAliasIfNecessary(Client client,
                     alias,
                     false,
                     ActionListener.wrap(
-                        unused -> updateWriteAlias(client, alias, legacyIndexWithoutSuffix, firstConcreteIndex, listener),
-                        listener::onFailure)
+                        unused -> updateWriteAlias(client, alias, legacyIndexWithoutSuffix, firstConcreteIndex, indexCreatedListener),
+                        finalListener::onFailure)
                 );
                 return;
             }
@@ -119,12 +136,28 @@ public static void createIndexAndAliasIfNecessary(Client client,
             if (indexPointedByCurrentWriteAlias.isEmpty()) {
                 assert concreteIndexNames.length > 0;
                 String latestConcreteIndexName = Arrays.stream(concreteIndexNames).max(INDEX_NAME_COMPARATOR).get();
-                updateWriteAlias(client, alias, null, latestConcreteIndexName, listener);
+                updateWriteAlias(client, alias, null, latestConcreteIndexName, finalListener);
                 return;
             }
         }
         // If the alias is set, there is nothing more to do.
-        listener.onResponse(false);
+        finalListener.onResponse(false);
+    }
+
+    private static void waitForShardsReady(Client client, String index, ActionListener<Boolean> listener) {
+        ClusterHealthRequest healthRequest = Requests.clusterHealthRequest(index)
+            .waitForYellowStatus()
+            .waitForNoRelocatingShards(true)
+            .waitForNoInitializingShards(true);
+        executeAsyncWithOrigin(
+            client.threadPool().getThreadContext(),
+            ML_ORIGIN,
+            healthRequest,
+            ActionListener.<ClusterHealthResponse>wrap(
+                response -> listener.onResponse(response.isTimedOut() == false),
+                listener::onFailure),
+            client.admin().cluster()::health
+        );
     }
 
     private static void createFirstConcreteIndex(Client client,

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/utils/MlIndexAndAliasTests.java

@@ -7,6 +7,8 @@
 
 import org.elasticsearch.Version;
 import org.elasticsearch.action.ActionListener;
+import org.elasticsearch.action.admin.cluster.health.ClusterHealthRequest;
+import org.elasticsearch.action.admin.cluster.health.ClusterHealthResponse;
 import org.elasticsearch.action.admin.indices.alias.Alias;
 import org.elasticsearch.action.admin.indices.alias.IndicesAliasesAction;
 import org.elasticsearch.action.admin.indices.alias.IndicesAliasesRequest;
@@ -19,6 +21,7 @@
 import org.elasticsearch.action.support.master.AcknowledgedResponse;
 import org.elasticsearch.client.AdminClient;
 import org.elasticsearch.client.Client;
+import org.elasticsearch.client.ClusterAdminClient;
 import org.elasticsearch.client.IndicesAdminClient;
 import org.elasticsearch.cluster.ClusterName;
 import org.elasticsearch.cluster.ClusterState;
@@ -66,6 +69,7 @@ public class MlIndexAndAliasTests extends ESTestCase {
 
     private ThreadPool threadPool;
     private IndicesAdminClient indicesAdminClient;
+    private ClusterAdminClient clusterAdminClient;
     private AdminClient adminClient;
     private Client client;
     private ActionListener<Boolean> listener;
@@ -85,8 +89,17 @@ public void setUpMocks() {
         when(indicesAdminClient.prepareAliases()).thenReturn(new IndicesAliasesRequestBuilder(client, IndicesAliasesAction.INSTANCE));
         doAnswer(withResponse(new AcknowledgedResponse(true))).when(indicesAdminClient).aliases(any(), any());
 
+        clusterAdminClient = mock(ClusterAdminClient.class);
+        doAnswer(invocationOnMock -> {
+            @SuppressWarnings("unchecked")
+            ActionListener<ClusterHealthResponse> listener = (ActionListener<ClusterHealthResponse>) invocationOnMock.getArguments()[1];
+            listener.onResponse(new ClusterHealthResponse());
+            return null;
+        }).when(clusterAdminClient).health(any(ClusterHealthRequest.class), any(ActionListener.class));
+
         adminClient = mock(AdminClient.class);
         when(adminClient.indices()).thenReturn(indicesAdminClient);
+        when(adminClient.cluster()).thenReturn(clusterAdminClient);
 
         client = mock(Client.class);
         when(client.threadPool()).thenReturn(threadPool);

x-pack/plugin/ml/qa/native-multi-node-tests/src/test/java/org/elasticsearch/xpack/ml/integration/DeleteExpiredDataIT.java

@@ -137,7 +137,6 @@ public void testDeleteExpiredDataActionDeletesEmptyStateIndices() throws Excepti
             is(arrayContaining(".ml-state-000001", ".ml-state-000005", ".ml-state-000007")));
     }
 
-    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/57102")
     public void testDeleteExpiredDataWithStandardThrottle() throws Exception {
         testExpiredDeletion(-1.0f, 100);
     }

x-pack/plugin/ml/qa/native-multi-node-tests/src/test/java/org/elasticsearch/xpack/ml/integration/RegressionIT.java

@@ -297,7 +297,6 @@ public void testStopAndRestart() throws Exception {
         assertMlResultsFieldMappings(destIndex, predictedClassField, "double");
     }
 
-    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/55807")
     public void testTwoJobsWithSameRandomizeSeedUseSameTrainingSet() throws Exception {
         String sourceIndex = "regression_two_jobs_with_same_randomize_seed_source";
         indexData(sourceIndex, 100, 0);