Rollover: refactor out cluster state update (elastic#53965)

Make it possible to reuse the cluster state update of rollover for
simulation purposes by extracting it. Also now run the full rollover in
the pre-rollover phase and the actual rollover phase, allowing a
dedicated exception in case of concurrent rollovers as well as a more
thorough pre-check.

server/src/main/java/org/elasticsearch/action/admin/indices/rollover/MetaDataRolloverService.java

@@ -0,0 +1,189 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch 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
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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.elasticsearch.action.admin.indices.rollover;
+
+import org.elasticsearch.action.admin.indices.create.CreateIndexClusterStateUpdateRequest;
+import org.elasticsearch.action.admin.indices.create.CreateIndexRequest;
+import org.elasticsearch.action.support.ActiveShardCount;
+import org.elasticsearch.cluster.ClusterState;
+import org.elasticsearch.cluster.metadata.AliasAction;
+import org.elasticsearch.cluster.metadata.AliasMetaData;
+import org.elasticsearch.cluster.metadata.AliasOrIndex;
+import org.elasticsearch.cluster.metadata.IndexMetaData;
+import org.elasticsearch.cluster.metadata.IndexNameExpressionResolver;
+import org.elasticsearch.cluster.metadata.IndexTemplateMetaData;
+import org.elasticsearch.cluster.metadata.MetaData;
+import org.elasticsearch.cluster.metadata.MetaDataCreateIndexService;
+import org.elasticsearch.cluster.metadata.MetaDataIndexAliasesService;
+import org.elasticsearch.common.Nullable;
+import org.elasticsearch.common.inject.Inject;
+import org.elasticsearch.threadpool.ThreadPool;
+
+import java.util.List;
+import java.util.Locale;
+import java.util.regex.Pattern;
+
+import static org.elasticsearch.cluster.metadata.MetaDataIndexTemplateService.findTemplates;
+
+public class MetaDataRolloverService {
+    private static final Pattern INDEX_NAME_PATTERN = Pattern.compile("^.*-\\d+$");
+
+    private final ThreadPool threadPool;
+    private final MetaDataCreateIndexService createIndexService;
+    private final MetaDataIndexAliasesService indexAliasesService;
+    private final IndexNameExpressionResolver indexNameExpressionResolver;
+
+    @Inject
+    public MetaDataRolloverService(ThreadPool threadPool,
+                                   MetaDataCreateIndexService createIndexService, MetaDataIndexAliasesService indexAliasesService,
+                                   IndexNameExpressionResolver indexNameExpressionResolver) {
+        this.threadPool = threadPool;
+        this.createIndexService = createIndexService;
+        this.indexAliasesService = indexAliasesService;
+        this.indexNameExpressionResolver = indexNameExpressionResolver;
+    }
+
+    public static class RolloverResult {
+        public final String rolloverIndexName;
+        public final String sourceIndexName;
+        public final ClusterState clusterState;
+
+        private RolloverResult(String rolloverIndexName, String sourceIndexName, ClusterState clusterState) {
+            this.rolloverIndexName = rolloverIndexName;
+            this.sourceIndexName = sourceIndexName;
+            this.clusterState = clusterState;
+        }
+    }
+
+    public RolloverResult rolloverClusterState(ClusterState currentState, String aliasName, String newIndexName,
+                                               CreateIndexRequest createIndexRequest, List<Condition<?>> metConditions,
+                                               boolean silent) throws Exception {
+        final MetaData metaData = currentState.metaData();
+        validate(metaData, aliasName);
+        final AliasOrIndex.Alias alias = (AliasOrIndex.Alias) metaData.getAliasAndIndexLookup().get(aliasName);
+        final IndexMetaData indexMetaData = alias.getWriteIndex();
+        final AliasMetaData aliasMetaData = indexMetaData.getAliases().get(alias.getAliasName());
+        final String sourceProvidedName = indexMetaData.getSettings().get(IndexMetaData.SETTING_INDEX_PROVIDED_NAME,
+            indexMetaData.getIndex().getName());
+        final String sourceIndexName = indexMetaData.getIndex().getName();
+        final String unresolvedName = (newIndexName != null)
+            ? newIndexName
+            : generateRolloverIndexName(sourceProvidedName, indexNameExpressionResolver);
+        final String rolloverIndexName = indexNameExpressionResolver.resolveDateMathExpression(unresolvedName);
+        final boolean explicitWriteIndex = Boolean.TRUE.equals(aliasMetaData.writeIndex());
+        final Boolean isHidden = IndexMetaData.INDEX_HIDDEN_SETTING.exists(createIndexRequest.settings()) ?
+            IndexMetaData.INDEX_HIDDEN_SETTING.get(createIndexRequest.settings()) : null;
+        createIndexService.validateIndexName(rolloverIndexName, currentState); // fails if the index already exists
+        checkNoDuplicatedAliasInIndexTemplate(metaData, rolloverIndexName, aliasName, isHidden);
+
+        CreateIndexClusterStateUpdateRequest createIndexClusterStateRequest =
+            prepareCreateIndexRequest(unresolvedName, rolloverIndexName, createIndexRequest);
+        ClusterState newState = createIndexService.applyCreateIndexRequest(currentState, createIndexClusterStateRequest, silent);
+        newState = indexAliasesService.applyAliasActions(newState,
+            rolloverAliasToNewIndex(sourceIndexName, rolloverIndexName, explicitWriteIndex, aliasMetaData.isHidden(), aliasName));
+
+        RolloverInfo rolloverInfo = new RolloverInfo(aliasName, metConditions, threadPool.absoluteTimeInMillis());
+        newState = ClusterState.builder(newState)
+            .metaData(MetaData.builder(newState.metaData())
+                .put(IndexMetaData.builder(newState.metaData().index(sourceIndexName))
+                    .putRolloverInfo(rolloverInfo))).build();
+
+        return new RolloverResult(rolloverIndexName, sourceIndexName, newState);
+    }
+
+    static String generateRolloverIndexName(String sourceIndexName, IndexNameExpressionResolver indexNameExpressionResolver) {
+        String resolvedName = indexNameExpressionResolver.resolveDateMathExpression(sourceIndexName);
+        final boolean isDateMath = sourceIndexName.equals(resolvedName) == false;
+        if (INDEX_NAME_PATTERN.matcher(resolvedName).matches()) {
+            int numberIndex = sourceIndexName.lastIndexOf("-");
+            assert numberIndex != -1 : "no separator '-' found";
+            int counter = Integer.parseInt(sourceIndexName.substring(numberIndex + 1,
+                isDateMath ? sourceIndexName.length()-1 : sourceIndexName.length()));
+            String newName = sourceIndexName.substring(0, numberIndex) + "-" + String.format(Locale.ROOT, "%06d", ++counter)
+                + (isDateMath ? ">" : "");
+            return newName;
+        } else {
+            throw new IllegalArgumentException("index name [" + sourceIndexName + "] does not match pattern '^.*-\\d+$'");
+        }
+    }
+
+    static CreateIndexClusterStateUpdateRequest prepareCreateIndexRequest(final String providedIndexName, final String targetIndexName,
+                                                                          CreateIndexRequest createIndexRequest) {
+        createIndexRequest.cause("rollover_index");
+        createIndexRequest.index(targetIndexName);
+        return new CreateIndexClusterStateUpdateRequest(
+            "rollover_index", targetIndexName, providedIndexName)
+            .ackTimeout(createIndexRequest.timeout())
+            .masterNodeTimeout(createIndexRequest.masterNodeTimeout())
+            .settings(createIndexRequest.settings())
+            .aliases(createIndexRequest.aliases())
+            .waitForActiveShards(ActiveShardCount.NONE) // not waiting for shards here, will wait on the alias switch operation
+            .mappings(createIndexRequest.mappings());
+    }
+
+    /**
+     * Creates the alias actions to reflect the alias rollover from the old (source) index to the new (target/rolled over) index. An
+     * alias pointing to multiple indices will have to be an explicit write index (ie. the old index alias has is_write_index set to true)
+     * in which case, after the rollover, the new index will need to be the explicit write index.
+     */
+    static List<AliasAction> rolloverAliasToNewIndex(String oldIndex, String newIndex, boolean explicitWriteIndex,
+                                                     @Nullable Boolean isHidden, String alias) {
+        if (explicitWriteIndex) {
+            return List.of(
+                new AliasAction.Add(newIndex, alias, null, null, null, true, isHidden),
+                new AliasAction.Add(oldIndex, alias, null, null, null, false, isHidden));
+        } else {
+            return List.of(
+                new AliasAction.Add(newIndex, alias, null, null, null, null, isHidden),
+                new AliasAction.Remove(oldIndex, alias));
+        }
+    }
+
+    /**
+     * If the newly created index matches with an index template whose aliases contains the rollover alias,
+     * the rollover alias will point to multiple indices. This causes indexing requests to be rejected.
+     * To avoid this, we make sure that there is no duplicated alias in index templates before creating a new index.
+     */
+    static void checkNoDuplicatedAliasInIndexTemplate(MetaData metaData, String rolloverIndexName, String rolloverRequestAlias,
+                                                      @Nullable Boolean isHidden) {
+        final List<IndexTemplateMetaData> matchedTemplates = findTemplates(metaData, rolloverIndexName, isHidden);
+        for (IndexTemplateMetaData template : matchedTemplates) {
+            if (template.aliases().containsKey(rolloverRequestAlias)) {
+                throw new IllegalArgumentException(String.format(Locale.ROOT,
+                    "Rollover alias [%s] can point to multiple indices, found duplicated alias [%s] in index template [%s]",
+                    rolloverRequestAlias, template.aliases().keys(), template.name()));
+            }
+        }
+    }
+
+    static void validate(MetaData metaData, String aliasName) {
+        final AliasOrIndex aliasOrIndex = metaData.getAliasAndIndexLookup().get(aliasName);
+        if (aliasOrIndex == null) {
+            throw new IllegalArgumentException("source alias does not exist");
+        }
+        if (aliasOrIndex.isAlias() == false) {
+            throw new IllegalArgumentException("source alias is a concrete index");
+        }
+        final AliasOrIndex.Alias alias = (AliasOrIndex.Alias) aliasOrIndex;
+        if (alias.getWriteIndex() == null) {
+            throw new IllegalArgumentException("source alias [" + alias.getAliasName() + "] does not point to a write index");
+        }
+    }
+}