Prevent field caps from failing due to can match failure (#134134)

`FieldCapabilitiesFetcher` performs a can-match in order to quickly
return an empty response if no shard can match. However, if can-match
fails for some reason, it can cause the field capabilities request to fail.

An example of that is when a semantic query is used as filter. can-match
will fail as it won't be able to expand the inference results of the query.

In cases like that, it makes no sense to fail the field capabilities request.
Instead, we should treat can-match as returning `true` to proceed.

This change does that by following suit with other callers of can-match.

Fixes #116106

Author: dimitris-athanasiou

docs/changelog/134134.yaml

@@ -0,0 +1,6 @@
+pr: 134134
+summary: Prevent field caps from failing due to can match failure
+area: Search
+type: bug
+issues:
+ - 116106

server/src/internalClusterTest/java/org/elasticsearch/search/fieldcaps/CCSFieldCapabilitiesIT.java

@@ -14,15 +14,12 @@
 import org.elasticsearch.action.fieldcaps.FieldCapabilitiesResponse;
 import org.elasticsearch.client.internal.Client;
 import org.elasticsearch.common.settings.Settings;
-import org.elasticsearch.plugins.Plugin;
-import org.elasticsearch.search.fieldcaps.FieldCapabilitiesIT.ExceptionOnRewriteQueryBuilder;
-import org.elasticsearch.search.fieldcaps.FieldCapabilitiesIT.ExceptionOnRewriteQueryPlugin;
+import org.elasticsearch.index.shard.IllegalIndexShardStateException;
 import org.elasticsearch.test.AbstractMultiClustersTestCase;
 import org.elasticsearch.transport.RemoteTransportException;
 
-import java.util.ArrayList;
+import java.io.IOException;
 import java.util.Arrays;
-import java.util.Collection;
 import java.util.List;
 
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
@@ -46,14 +43,7 @@ protected boolean reuseClusters() {
         return false;
     }
 
-    @Override
-    protected Collection<Class<? extends Plugin>> nodePlugins(String clusterAlias) {
-        final List<Class<? extends Plugin>> plugins = new ArrayList<>(super.nodePlugins(clusterAlias));
-        plugins.add(ExceptionOnRewriteQueryPlugin.class);
-        return plugins;
-    }
-
-    public void testFailuresFromRemote() {
+    public void testFailuresFromRemote() throws IOException {
         Settings indexSettings = Settings.builder().put("index.number_of_replicas", 0).build();
         final Client localClient = client(LOCAL_CLUSTER);
         final Client remoteClient = client("remote_cluster");
@@ -71,11 +61,10 @@ public void testFailuresFromRemote() {
         FieldCapabilitiesResponse response = client().prepareFieldCaps("*", "remote_cluster:*").setFields("*").get();
         assertThat(Arrays.asList(response.getIndices()), containsInAnyOrder(localIndex, "remote_cluster:" + remoteErrorIndex));
 
-        // adding an index filter so remote call should fail
-        response = client().prepareFieldCaps("*", "remote_cluster:*")
-            .setFields("*")
-            .setIndexFilter(new ExceptionOnRewriteQueryBuilder())
-            .get();
+        // Closed shards will result to index error because shards must be in readable state
+        FieldCapabilitiesIT.closeShards(cluster("remote_cluster"), remoteErrorIndex);
+
+        response = client().prepareFieldCaps("*", "remote_cluster:*").setFields("*").get();
         assertThat(response.getIndices()[0], equalTo(localIndex));
         assertThat(response.getFailedIndicesCount(), equalTo(1));
         FieldCapabilitiesFailure failure = response.getFailures()
@@ -86,25 +75,22 @@ public void testFailuresFromRemote() {
         Exception ex = failure.getException();
         assertEquals(RemoteTransportException.class, ex.getClass());
         Throwable cause = ExceptionsHelper.unwrapCause(ex);
-        assertEquals(IllegalArgumentException.class, cause.getClass());
-        assertEquals("I throw because I choose to.", cause.getMessage());
+        assertEquals(IllegalIndexShardStateException.class, cause.getClass());
+        assertEquals(
+            "CurrentState[CLOSED] operations only allowed when shard state is one of [POST_RECOVERY, STARTED]",
+            cause.getMessage()
+        );
 
         // if we only query the remote we should get back an exception only
-        ex = expectThrows(
-            IllegalArgumentException.class,
-            client().prepareFieldCaps("remote_cluster:*").setFields("*").setIndexFilter(new ExceptionOnRewriteQueryBuilder())
-        );
-        assertEquals("I throw because I choose to.", ex.getMessage());
+        ex = expectThrows(IllegalIndexShardStateException.class, client().prepareFieldCaps("remote_cluster:*").setFields("*"));
+        assertEquals("CurrentState[CLOSED] operations only allowed when shard state is one of [POST_RECOVERY, STARTED]", ex.getMessage());
 
         // add an index that doesn't fail to the remote
         assertAcked(remoteClient.admin().indices().prepareCreate("okay_remote_index"));
         remoteClient.prepareIndex("okay_remote_index").setId("2").setSource("foo", "bar").get();
         remoteClient.admin().indices().prepareRefresh("okay_remote_index").get();
 
-        response = client().prepareFieldCaps("*", "remote_cluster:*")
-            .setFields("*")
-            .setIndexFilter(new ExceptionOnRewriteQueryBuilder())
-            .get();
+        response = client().prepareFieldCaps("*", "remote_cluster:*").setFields("*").get();
         assertThat(Arrays.asList(response.getIndices()), containsInAnyOrder(localIndex, "remote_cluster:okay_remote_index"));
         assertThat(response.getFailedIndicesCount(), equalTo(1));
         failure = response.getFailures()
@@ -113,8 +99,8 @@ public void testFailuresFromRemote() {
             .findFirst()
             .get();
         ex = failure.getException();
-        assertEquals(IllegalArgumentException.class, ex.getClass());
-        assertEquals("I throw because I choose to.", ex.getMessage());
+        assertEquals(IllegalIndexShardStateException.class, ex.getClass());
+        assertEquals("CurrentState[CLOSED] operations only allowed when shard state is one of [POST_RECOVERY, STARTED]", ex.getMessage());
     }
 
     public void testFailedToConnectToRemoteCluster() throws Exception {

server/src/internalClusterTest/java/org/elasticsearch/search/fieldcaps/FieldCapabilitiesIT.java

@@ -47,7 +47,7 @@
 import org.elasticsearch.index.query.QueryBuilder;
 import org.elasticsearch.index.query.QueryBuilders;
 import org.elasticsearch.index.query.QueryRewriteContext;
-import org.elasticsearch.index.query.SearchExecutionContext;
+import org.elasticsearch.index.shard.IllegalIndexShardStateException;
 import org.elasticsearch.index.shard.IndexShard;
 import org.elasticsearch.index.shard.ShardId;
 import org.elasticsearch.indices.IndexClosedException;
@@ -59,6 +59,7 @@
 import org.elasticsearch.search.DummyQueryBuilder;
 import org.elasticsearch.tasks.TaskInfo;
 import org.elasticsearch.test.ESIntegTestCase;
+import org.elasticsearch.test.InternalTestCluster;
 import org.elasticsearch.test.MockLog;
 import org.elasticsearch.test.junit.annotations.TestLogging;
 import org.elasticsearch.test.transport.MockTransportService;
@@ -78,6 +79,7 @@
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.concurrent.CancellationException;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
@@ -87,7 +89,6 @@
 import java.util.function.Predicate;
 import java.util.stream.IntStream;
 
-import static java.util.Collections.singletonList;
 import static org.elasticsearch.action.support.ActionTestUtils.wrapAsRestResponseListener;
 import static org.elasticsearch.index.shard.IndexShardTestCase.closeShardNoCheck;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
@@ -193,7 +194,7 @@ public void setUp() throws Exception {
 
     @Override
     protected Collection<Class<? extends Plugin>> nodePlugins() {
-        return List.of(TestMapperPlugin.class, ExceptionOnRewriteQueryPlugin.class, BlockingOnRewriteQueryPlugin.class);
+        return List.of(TestMapperPlugin.class, BlockingOnRewriteQueryPlugin.class);
     }
 
     @Override
@@ -445,30 +446,36 @@ public void testFieldMetricsAndDimensions() {
         assertThat(response.get().get("some_dimension").get("keyword").nonDimensionIndices(), array(equalTo("new_index")));
     }
 
-    public void testFailures() throws InterruptedException {
+    public void testFailures() throws IOException {
         // in addition to the existing "old_index" and "new_index", create two where the test query throws an error on rewrite
         assertAcked(prepareCreate("index1-error"), prepareCreate("index2-error"));
         ensureGreen("index1-error", "index2-error");
-        FieldCapabilitiesResponse response = client().prepareFieldCaps()
+
+        // Closed shards will result to index error because shards must be in readable state
+        closeShards(internalCluster(), "index1-error", "index2-error");
+
+        FieldCapabilitiesResponse response = client().prepareFieldCaps("old_index", "new_index", "index1-error", "index2-error")
             .setFields("*")
-            .setIndexFilter(new ExceptionOnRewriteQueryBuilder())
             .get();
         assertEquals(1, response.getFailures().size());
         assertEquals(2, response.getFailedIndicesCount());
         assertThat(response.getFailures().get(0).getIndices(), arrayContainingInAnyOrder("index1-error", "index2-error"));
         Exception failure = response.getFailures().get(0).getException();
-        assertEquals(IllegalArgumentException.class, failure.getClass());
-        assertEquals("I throw because I choose to.", failure.getMessage());
+        assertEquals(IllegalIndexShardStateException.class, failure.getClass());
+        assertEquals(
+            "CurrentState[CLOSED] operations only allowed when shard state is one of [POST_RECOVERY, STARTED]",
+            failure.getMessage()
+        );
 
         // the "indices" section should not include failed ones
         assertThat(Arrays.asList(response.getIndices()), containsInAnyOrder("old_index", "new_index"));
 
         // if all requested indices failed, we fail the request by throwing the exception
-        IllegalArgumentException ex = expectThrows(
-            IllegalArgumentException.class,
-            client().prepareFieldCaps("index1-error", "index2-error").setFields("*").setIndexFilter(new ExceptionOnRewriteQueryBuilder())
+        IllegalIndexShardStateException ex = expectThrows(
+            IllegalIndexShardStateException.class,
+            client().prepareFieldCaps("index1-error", "index2-error").setFields("*")
         );
-        assertEquals("I throw because I choose to.", ex.getMessage());
+        assertEquals("CurrentState[CLOSED] operations only allowed when shard state is one of [POST_RECOVERY, STARTED]", ex.getMessage());
     }
 
     private void populateTimeRangeIndices() throws Exception {
@@ -913,45 +920,17 @@ private void assertIndices(FieldCapabilitiesResponse response, String... indices
         assertArrayEquals(indices, response.getIndices());
     }
 
-    /**
-     * Adds an "exception" query that  throws on rewrite if the index name contains the string "error"
-     */
-    public static class ExceptionOnRewriteQueryPlugin extends Plugin implements SearchPlugin {
-
-        public ExceptionOnRewriteQueryPlugin() {}
-
-        @Override
-        public List<QuerySpec<?>> getQueries() {
-            return singletonList(
-                new QuerySpec<>("exception", ExceptionOnRewriteQueryBuilder::new, p -> new ExceptionOnRewriteQueryBuilder())
-            );
-        }
-    }
-
-    static class ExceptionOnRewriteQueryBuilder extends DummyQueryBuilder {
-
-        public static final String NAME = "exception";
-
-        ExceptionOnRewriteQueryBuilder() {}
-
-        ExceptionOnRewriteQueryBuilder(StreamInput in) throws IOException {
-            super(in);
-        }
-
-        @Override
-        protected QueryBuilder doRewrite(QueryRewriteContext queryRewriteContext) throws IOException {
-            SearchExecutionContext searchExecutionContext = queryRewriteContext.convertToSearchExecutionContext();
-            if (searchExecutionContext != null) {
-                if (searchExecutionContext.indexMatches("*error*")) {
-                    throw new IllegalArgumentException("I throw because I choose to.");
+    static void closeShards(InternalTestCluster cluster, String... indices) throws IOException {
+        final Set<String> indicesToClose = Set.of(indices);
+        for (String node : cluster.getNodeNames()) {
+            final IndicesService indicesService = cluster.getInstance(IndicesService.class, node);
+            for (IndexService indexService : indicesService) {
+                if (indicesToClose.contains(indexService.getMetadata().getIndex().getName())) {
+                    for (IndexShard indexShard : indexService) {
+                        closeShardNoCheck(indexShard);
+                    }
                 }
             }
-            return this;
-        }
-
-        @Override
-        public String getWriteableName() {
-            return NAME;
         }
     }
 

server/src/main/java/org/elasticsearch/action/fieldcaps/FieldCapabilitiesFetcher.java

@@ -249,12 +249,17 @@ private static boolean canMatchShard(
         QueryBuilder indexFilter,
         long nowInMillis,
         SearchExecutionContext searchExecutionContext
-    ) throws IOException {
+    ) {
         assert alwaysMatches(indexFilter) == false : "should not be called for always matching [" + indexFilter + "]";
         assert nowInMillis != 0L;
         ShardSearchRequest searchRequest = new ShardSearchRequest(shardId, nowInMillis, AliasFilter.EMPTY);
         searchRequest.source(new SearchSourceBuilder().query(indexFilter));
-        return SearchService.queryStillMatchesAfterRewrite(searchRequest, searchExecutionContext);
+        try {
+            return SearchService.queryStillMatchesAfterRewrite(searchRequest, searchExecutionContext);
+        } catch (Exception e) {
+            // treat as if shard is still a potential match
+            return true;
+        }
     }
 
     private static boolean alwaysMatches(QueryBuilder indexFilter) {

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/InferenceFeatures.java

@@ -84,7 +84,8 @@ public Set<NodeFeature> getTestFeatures() {
                 SEMANTIC_TEXT_HIGHLIGHTING_FLAT,
                 SEMANTIC_TEXT_SPARSE_VECTOR_INDEX_OPTIONS,
                 SEMANTIC_TEXT_FIELDS_CHUNKS_FORMAT,
-                SemanticQueryBuilder.SEMANTIC_QUERY_MULTIPLE_INFERENCE_IDS
+                SemanticQueryBuilder.SEMANTIC_QUERY_MULTIPLE_INFERENCE_IDS,
+                SemanticQueryBuilder.SEMANTIC_QUERY_FILTER_FIELD_CAPS_FIX
             )
         );
         if (RERANK_SNIPPETS.isEnabled()) {

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/queries/SemanticQueryBuilder.java

@@ -56,6 +56,7 @@ public class SemanticQueryBuilder extends AbstractQueryBuilder<SemanticQueryBuil
     public static final String NAME = "semantic";
 
     public static final NodeFeature SEMANTIC_QUERY_MULTIPLE_INFERENCE_IDS = new NodeFeature("semantic_query.multiple_inference_ids");
+    public static final NodeFeature SEMANTIC_QUERY_FILTER_FIELD_CAPS_FIX = new NodeFeature("semantic_query.filter_field_caps_fix");
 
     private static final TransportVersion SEMANTIC_QUERY_MULTIPLE_INFERENCE_IDS_TV = TransportVersion.fromName(
         "semantic_query_multiple_inference_ids"

x-pack/plugin/inference/src/yamlRestTest/resources/rest-api-spec/test/inference/10_semantic_text_field_mapping.yml

@@ -548,6 +548,33 @@ setup:
   - not_exists: fields.dense_field.inference.chunks
   - not_exists: fields.dense_field.inference
 
+---
+"Field caps with semantic query does not fail":
+  - requires:
+      cluster_features: "semantic_query.filter_field_caps_fix"
+      reason: "fixed bug with semantic query filtering in field_caps (#116106)"
+  # We need at least one document present to exercise can-match phase
+  - do:
+      index:
+        index: test-index
+        id: doc_1
+        body:
+          sparse_field: "This is a story about a cat and a dog."
+        refresh: true
+
+  - do:
+      field_caps:
+        index: test-index
+        fields: "*"
+        body:
+          index_filter:
+            semantic:
+              field: "sparse_field"
+              query: "test"
+
+  - match: { indices: [ "test-index" ] }
+  - match: { fields.sparse_field.text.searchable: true }
+
 ---
 "Users can set dense vector index options and index documents using those options":
   - requires:

x-pack/plugin/inference/src/yamlRestTest/resources/rest-api-spec/test/inference/10_semantic_text_field_mapping_bwc.yml

@@ -447,6 +447,34 @@ setup:
   - not_exists: fields.dense_field.inference.chunks.text
   - not_exists: fields.dense_field.inference.chunks
   - not_exists: fields.dense_field.inference
+
+---
+"Field caps with semantic query does not fail":
+  - requires:
+      cluster_features: "semantic_query.filter_field_caps_fix"
+      reason: "fixed bug with semantic query filtering in field_caps (#116106)"
+  # We need at least one document present to exercise can-match phase
+  - do:
+      index:
+        index: test-index
+        id: doc_1
+        body:
+          sparse_field: "This is a story about a cat and a dog."
+        refresh: true
+
+  - do:
+      field_caps:
+        index: test-index
+        fields: "*"
+        body:
+          index_filter:
+            semantic:
+              field: "sparse_field"
+              query: "test"
+
+  - match: { indices: [ "test-index" ] }
+  - match: { fields.sparse_field.text.searchable: true }
+
 ---
 "Users can set dense vector index options and index documents using those options":
   - requires: