Enable flat index expressions support for _field_caps

Author: pawankartik-elastic

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

@@ -243,6 +243,11 @@ public boolean allowsRemoteIndices() {
         return true;
     }
 
+    @Override
+    public boolean allowsCrossProject() {
+        return true;
+    }
+
     @Override
     public boolean includeDataStreams() {
         return true;

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

@@ -50,6 +50,7 @@
 import org.elasticsearch.logging.LogManager;
 import org.elasticsearch.logging.Logger;
 import org.elasticsearch.search.SearchService;
+import org.elasticsearch.search.crossproject.CrossProjectModeDecider;
 import org.elasticsearch.tasks.CancellableTask;
 import org.elasticsearch.tasks.Task;
 import org.elasticsearch.threadpool.ThreadPool;
@@ -81,6 +82,7 @@
 import java.util.stream.Collectors;
 
 import static org.elasticsearch.action.search.TransportSearchHelper.checkCCSVersionCompatibility;
+import static org.elasticsearch.search.crossproject.CrossProjectIndexResolutionValidator.indicesOptionsForCrossProjectFanout;
 
 public class TransportFieldCapabilitiesAction extends HandledTransportAction<FieldCapabilitiesRequest, FieldCapabilitiesResponse> {
     public static final String NAME = "indices:data/read/field_caps";
@@ -102,6 +104,7 @@ public class TransportFieldCapabilitiesAction extends HandledTransportAction<Fie
     private final boolean ccsCheckCompatibility;
     private final ThreadPool threadPool;
     private final TimeValue forceConnectTimeoutSecs;
+    private final CrossProjectModeDecider crossProjectModeDecider;
 
     @Inject
     public TransportFieldCapabilitiesAction(
@@ -130,6 +133,7 @@ public TransportFieldCapabilitiesAction(
         this.ccsCheckCompatibility = SearchService.CCS_VERSION_CHECK_SETTING.get(clusterService.getSettings());
         this.threadPool = threadPool;
         this.forceConnectTimeoutSecs = clusterService.getSettings().getAsTime("search.ccs.force_connect_timeout", null);
+        this.crossProjectModeDecider = new CrossProjectModeDecider(clusterService.getSettings());
     }
 
     @Override
@@ -310,7 +314,13 @@ private <R extends ActionResponse> void doExecuteForked(
             for (Map.Entry<String, OriginalIndices> remoteIndices : remoteClusterIndices.entrySet()) {
                 String clusterAlias = remoteIndices.getKey();
                 OriginalIndices originalIndices = remoteIndices.getValue();
-                FieldCapabilitiesRequest remoteRequest = prepareRemoteRequest(clusterAlias, request, originalIndices, nowInMillis);
+                FieldCapabilitiesRequest remoteRequest = prepareRemoteRequest(
+                    clusterAlias,
+                    request,
+                    originalIndices,
+                    nowInMillis,
+                    crossProjectModeDecider
+                );
                 ActionListener<FieldCapabilitiesResponse> remoteListener = ActionListener.wrap(response -> {
                     for (FieldCapabilitiesIndexResponse resp : response.getIndexResponses()) {
                         String indexName = RemoteClusterAware.buildRemoteIndexName(clusterAlias, resp.getIndexName());
@@ -475,12 +485,17 @@ private static FieldCapabilitiesRequest prepareRemoteRequest(
         String clusterAlias,
         FieldCapabilitiesRequest request,
         OriginalIndices originalIndices,
-        long nowInMillis
+        long nowInMillis,
+        CrossProjectModeDecider crossProjectModeDecider
     ) {
         FieldCapabilitiesRequest remoteRequest = new FieldCapabilitiesRequest();
         remoteRequest.clusterAlias(clusterAlias);
         remoteRequest.setMergeResults(false); // we need to merge on this node
         remoteRequest.indicesOptions(originalIndices.indicesOptions());
+        if (crossProjectModeDecider.resolvesCrossProject(request)) {
+            remoteRequest.indicesOptions(indicesOptionsForCrossProjectFanout(remoteRequest.indicesOptions()));
+        }
+
         remoteRequest.indices(originalIndices.indices());
         remoteRequest.fields(request.fields());
         remoteRequest.filters(request.filters());

server/src/main/java/org/elasticsearch/rest/action/RestFieldCapabilitiesAction.java

@@ -18,6 +18,7 @@
 import org.elasticsearch.rest.RestRequest;
 import org.elasticsearch.rest.Scope;
 import org.elasticsearch.rest.ServerlessScope;
+import org.elasticsearch.search.crossproject.CrossProjectModeDecider;
 import org.elasticsearch.xcontent.ObjectParser;
 import org.elasticsearch.xcontent.ParseField;
 
@@ -33,9 +34,11 @@
 public class RestFieldCapabilitiesAction extends BaseRestHandler {
 
     private final Settings settings;
+    private final CrossProjectModeDecider crossProjectModeDecider;
 
     public RestFieldCapabilitiesAction(Settings settings) {
         this.settings = settings;
+        this.crossProjectModeDecider = new CrossProjectModeDecider(settings);
     }
 
     @Override
@@ -55,14 +58,21 @@ public String getName() {
 
     @Override
     public RestChannelConsumer prepareRequest(final RestRequest request, final NodeClient client) throws IOException {
-        if (settings != null && settings.getAsBoolean("serverless.cross_project.enabled", false)) {
+        final boolean crossProjectEnabled = crossProjectModeDecider.crossProjectEnabled();
+        if (crossProjectModeDecider.crossProjectEnabled()) {
             // accept but drop project_routing param until fully supported
             request.param("project_routing");
         }
 
         final String[] indices = Strings.splitStringByCommaToArray(request.param("index"));
         final FieldCapabilitiesRequest fieldRequest = new FieldCapabilitiesRequest();
         fieldRequest.indices(indices);
+        if (crossProjectEnabled && fieldRequest.allowsCrossProject()) {
+            var cpsIdxOpts = IndicesOptions.builder(fieldRequest.indicesOptions())
+                .crossProjectModeOptions(new IndicesOptions.CrossProjectModeOptions(true))
+                .build();
+            fieldRequest.indicesOptions(cpsIdxOpts);
+        }
 
         fieldRequest.indicesOptions(IndicesOptions.fromRequest(request, fieldRequest.indicesOptions()));
         fieldRequest.includeUnmapped(request.paramAsBoolean("include_unmapped", false));