Fail rollover if duplicated alias found in template (#28110)

If a newly created index from a rollover request matches with an index 
template whose aliases contains the rollover request alias, the alias
will point to multiple indices. This will cause indexing requests to be 
rejected. To avoid such situation, we make sure that there is no
duplicated alias before creating a new index; otherwise abort and report
an error to the caller.

Closes #26976

core/src/main/java/org/elasticsearch/action/admin/indices/rollover/TransportRolloverAction.java

@@ -37,9 +37,11 @@
 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.cluster.metadata.MetaDataIndexTemplateService;
 import org.elasticsearch.cluster.service.ClusterService;
 import org.elasticsearch.common.inject.Inject;
 import org.elasticsearch.common.settings.Settings;
@@ -115,6 +117,7 @@ protected void masterOperation(final RolloverRequest rolloverRequest, final Clus
             : generateRolloverIndexName(sourceProvidedName, indexNameExpressionResolver);
         final String rolloverIndexName = indexNameExpressionResolver.resolveDateMathExpression(unresolvedName);
         MetaDataCreateIndexService.validateIndexName(rolloverIndexName, state); // will fail if the index already exists
+        checkNoDuplicatedAliasInIndexTemplate(metaData, rolloverIndexName, rolloverRequest.getAlias());
         client.admin().indices().prepareStats(sourceIndexName).clear().setDocs(true).execute(
             new ActionListener<IndicesStatsResponse>() {
                 @Override
@@ -238,4 +241,19 @@ static CreateIndexClusterStateUpdateRequest prepareCreateIndexRequest(final Stri
             .mappings(createIndexRequest.mappings());
     }
 
+    /**
+     * 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) {
+        final List<IndexTemplateMetaData> matchedTemplates = MetaDataIndexTemplateService.findTemplates(metaData, rolloverIndexName);
+        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()));
+            }
+        }
+    }
 }

core/src/main/java/org/elasticsearch/cluster/metadata/MetaDataCreateIndexService.java

@@ -277,7 +277,7 @@ public ClusterState execute(ClusterState currentState) throws Exception {
 
                 // we only find a template when its an API call (a new index)
                 // find templates, highest order are better matching
-                List<IndexTemplateMetaData> templates = findTemplates(request, currentState);
+                List<IndexTemplateMetaData> templates = MetaDataIndexTemplateService.findTemplates(currentState.metaData(), request.index());
 
                 Map<String, Custom> customs = new HashMap<>();
 
@@ -564,22 +564,6 @@ public void onFailure(String source, Exception e) {
             }
             super.onFailure(source, e);
         }
-
-        private List<IndexTemplateMetaData> findTemplates(CreateIndexClusterStateUpdateRequest request, ClusterState state) throws IOException {
-            List<IndexTemplateMetaData> templateMetadata = new ArrayList<>();
-            for (ObjectCursor<IndexTemplateMetaData> cursor : state.metaData().templates().values()) {
-                IndexTemplateMetaData metadata = cursor.value;
-                for (String template: metadata.patterns()) {
-                    if (Regex.simpleMatch(template, request.index())) {
-                        templateMetadata.add(metadata);
-                        break;
-                    }
-                }
-            }
-
-            CollectionUtil.timSort(templateMetadata, Comparator.comparingInt(IndexTemplateMetaData::order).reversed());
-            return templateMetadata;
-        }
     }
 
     private void validate(CreateIndexClusterStateUpdateRequest request, ClusterState state) {

core/src/main/java/org/elasticsearch/cluster/metadata/MetaDataIndexTemplateService.java

@@ -20,6 +20,7 @@
 
 import com.carrotsearch.hppc.cursors.ObjectCursor;
 
+import org.apache.lucene.util.CollectionUtil;
 import org.elasticsearch.Version;
 import org.elasticsearch.action.admin.indices.alias.Alias;
 import org.elasticsearch.action.support.master.MasterNodeRequest;
@@ -48,6 +49,7 @@
 
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
@@ -193,6 +195,23 @@ public void clusterStateProcessed(String source, ClusterState oldState, ClusterS
         });
     }
 
+    /**
+     * Finds index templates whose index pattern matched with the given index name.
+     * The result is sorted by {@link IndexTemplateMetaData#order} descending.
+     */
+    public static List<IndexTemplateMetaData> findTemplates(MetaData metaData, String indexName) {
+        final List<IndexTemplateMetaData> matchedTemplates = new ArrayList<>();
+        for (ObjectCursor<IndexTemplateMetaData> cursor : metaData.templates().values()) {
+            final IndexTemplateMetaData template = cursor.value;
+            final boolean matched = template.patterns().stream().anyMatch(pattern -> Regex.simpleMatch(pattern, indexName));
+            if (matched) {
+                matchedTemplates.add(template);
+            }
+        }
+        CollectionUtil.timSort(matchedTemplates, Comparator.comparingInt(IndexTemplateMetaData::order).reversed());
+        return matchedTemplates;
+    }
+
     private static void validateAndAddTemplate(final PutRequest request, IndexTemplateMetaData.Builder templateBuilder,
             IndicesService indicesService, NamedXContentRegistry xContentRegistry) throws Exception {
         Index createdIndex = null;

core/src/test/java/org/elasticsearch/action/admin/indices/rollover/RolloverIT.java

@@ -277,4 +277,15 @@ public void testRolloverMaxSize() throws Exception {
             assertThat("No rollover with an empty index", response.isRolledOver(), equalTo(false));
         }
     }
+
+    public void testRejectIfAliasFoundInTemplate() throws Exception {
+        client().admin().indices().preparePutTemplate("logs")
+            .setPatterns(Collections.singletonList("logs-*")).addAlias(new Alias("logs-write")).get();
+        assertAcked(client().admin().indices().prepareCreate("logs-000001").get());
+        ensureYellow("logs-write");
+        final IllegalArgumentException error = expectThrows(IllegalArgumentException.class,
+            () -> client().admin().indices().prepareRolloverIndex("logs-write").addMaxIndexSizeCondition(new ByteSizeValue(1)).get());
+        assertThat(error.getMessage(), equalTo(
+            "Rollover alias [logs-write] can point to multiple indices, found duplicated alias [[logs-write]] in index template [logs]"));
+    }
 }

core/src/test/java/org/elasticsearch/action/admin/indices/rollover/TransportRolloverActionTests.java

@@ -29,6 +29,7 @@
 import org.elasticsearch.cluster.metadata.AliasMetaData;
 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.common.UUIDs;
 import org.elasticsearch.common.settings.Settings;
@@ -40,11 +41,13 @@
 import org.elasticsearch.test.ESTestCase;
 import org.mockito.ArgumentCaptor;
 
+import java.util.Arrays;
 import java.util.List;
 import java.util.Locale;
 import java.util.Set;
 
 import static org.elasticsearch.action.admin.indices.rollover.TransportRolloverAction.evaluateConditions;
+import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.hasSize;
 import static org.mockito.Matchers.any;
@@ -241,6 +244,19 @@ public void testCreateIndexRequest() throws Exception {
         assertThat(createIndexRequest.cause(), equalTo("rollover_index"));
     }
 
+    public void testRejectDuplicateAlias() throws Exception {
+        final IndexTemplateMetaData template = IndexTemplateMetaData.builder("test-template")
+            .patterns(Arrays.asList("foo-*", "bar-*"))
+            .putAlias(AliasMetaData.builder("foo-write")).putAlias(AliasMetaData.builder("bar-write"))
+            .build();
+        final MetaData metaData = MetaData.builder().put(createMetaData(), false).put(template).build();
+        String indexName = randomFrom("foo-123", "bar-xyz");
+        String aliasName = randomFrom("foo-write", "bar-write");
+        final IllegalArgumentException ex = expectThrows(IllegalArgumentException.class,
+            () -> TransportRolloverAction.checkNoDuplicatedAliasInIndexTemplate(metaData, indexName, aliasName));
+        assertThat(ex.getMessage(), containsString("index template [test-template]"));
+    }
+
     private IndicesStatsResponse createIndicesStatResponse(long totalDocs, long primaryDocs) {
         final CommonStats primaryStats = mock(CommonStats.class);
         when(primaryStats.getDocs()).thenReturn(new DocsStats(primaryDocs, 0, between(1, 10000)));

core/src/test/java/org/elasticsearch/action/admin/indices/template/put/MetaDataIndexTemplateServiceTests.java

@@ -20,8 +20,10 @@
 package org.elasticsearch.action.admin.indices.template.put;
 
 import org.elasticsearch.action.admin.indices.alias.Alias;
+import org.elasticsearch.cluster.ClusterState;
 import org.elasticsearch.cluster.metadata.AliasValidator;
 import org.elasticsearch.cluster.metadata.IndexMetaData;
+import org.elasticsearch.cluster.metadata.IndexTemplateMetaData;
 import org.elasticsearch.cluster.metadata.MetaDataCreateIndexService;
 import org.elasticsearch.cluster.metadata.MetaDataIndexTemplateService;
 import org.elasticsearch.cluster.metadata.MetaDataIndexTemplateService.PutRequest;
@@ -38,16 +40,17 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
-import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
-import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.CountDownLatch;
+import java.util.stream.Collectors;
 
 import static org.hamcrest.CoreMatchers.containsString;
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.hamcrest.CoreMatchers.instanceOf;
+import static org.hamcrest.Matchers.contains;
+import static org.hamcrest.Matchers.empty;
 
 public class MetaDataIndexTemplateServiceTests extends ESSingleNodeTestCase {
     public void testIndexTemplateInvalidNumberOfShards() {
@@ -154,6 +157,18 @@ public void testAliasInvalidFilterInvalidJson() throws Exception {
         assertThat(errors.get(0).getMessage(), equalTo("failed to parse filter for alias [invalid_alias]"));
     }
 
+    public void testFindTemplates() throws Exception {
+        client().admin().indices().prepareDeleteTemplate("*").get(); // Delete all existing templates
+        putTemplateDetail(new PutRequest("test", "foo-1").patterns(Arrays.asList("foo-*")).order(1));
+        putTemplateDetail(new PutRequest("test", "foo-2").patterns(Arrays.asList("foo-*")).order(2));
+        putTemplateDetail(new PutRequest("test", "bar").patterns(Arrays.asList("bar-*")).order(between(0, 100)));
+        final ClusterState state = client().admin().cluster().prepareState().get().getState();
+        assertThat(MetaDataIndexTemplateService.findTemplates(state.metaData(), "foo-1234").stream()
+            .map(IndexTemplateMetaData::name).collect(Collectors.toList()), contains("foo-2", "foo-1"));
+        assertThat(MetaDataIndexTemplateService.findTemplates(state.metaData(), "bar-xyz").stream()
+            .map(IndexTemplateMetaData::name).collect(Collectors.toList()), contains("bar"));
+        assertThat(MetaDataIndexTemplateService.findTemplates(state.metaData(), "baz"), empty());
+    }
 
     private static List<Throwable> putTemplate(NamedXContentRegistry xContentRegistry, PutRequest request) {
         MetaDataCreateIndexService createIndexService = new MetaDataCreateIndexService(