Add project routing telemetry infrastructure

server/src/main/java/org/elasticsearch/action/ActionModule.java

@@ -540,6 +540,13 @@ public ActionModule(
         );
         this.restExtension = restExtension;
         this.clusterService = clusterService;
+
+        actionPlugins.stream()
+            .map(ActionPlugin::getClusterStatsTagsProvider)
+            .filter(Optional::isPresent)
+            .map(Optional::get)
+            .findFirst()
+            .ifPresent(usageService::registerTagsProvider);
     }
 
     private static <T> T getRestServerComponent(

server/src/main/java/org/elasticsearch/action/admin/cluster/stats/ClusterStatsNodeResponse.java

@@ -9,6 +9,7 @@
 
 package org.elasticsearch.action.admin.cluster.stats;
 
+import org.elasticsearch.TransportVersion;
 import org.elasticsearch.action.admin.cluster.node.info.NodeInfo;
 import org.elasticsearch.action.admin.cluster.node.stats.NodeStats;
 import org.elasticsearch.action.admin.indices.stats.ShardStats;
@@ -24,6 +25,8 @@
 
 public class ClusterStatsNodeResponse extends BaseNodeResponse {
 
+    static final TransportVersion PROJECT_ROUTING_USAGE_STATS = TransportVersion.fromName("project_routing_usage_stats");
+
     private final NodeInfo nodeInfo;
     private final NodeStats nodeStats;
     private final ShardStats[] shardsStats;
@@ -32,6 +35,7 @@ public class ClusterStatsNodeResponse extends BaseNodeResponse {
     private final RepositoryUsageStats repositoryUsageStats;
     private final CCSTelemetrySnapshot searchCcsMetrics;
     private final CCSTelemetrySnapshot esqlCcsMetrics;
+    private final ProjectRoutingUsageSnapshot projectRoutingUsageSnapshot;
 
     public ClusterStatsNodeResponse(StreamInput in) throws IOException {
         super(in);
@@ -43,6 +47,9 @@ public ClusterStatsNodeResponse(StreamInput in) throws IOException {
         repositoryUsageStats = RepositoryUsageStats.readFrom(in);
         searchCcsMetrics = new CCSTelemetrySnapshot(in);
         esqlCcsMetrics = new CCSTelemetrySnapshot(in);
+        projectRoutingUsageSnapshot = in.getTransportVersion().supports(PROJECT_ROUTING_USAGE_STATS)
+            ? new ProjectRoutingUsageSnapshot(in)
+            : new ProjectRoutingUsageSnapshot();
     }
 
     public ClusterStatsNodeResponse(
@@ -54,7 +61,8 @@ public ClusterStatsNodeResponse(
         SearchUsageStats searchUsageStats,
         RepositoryUsageStats repositoryUsageStats,
         CCSTelemetrySnapshot ccsTelemetrySnapshot,
-        CCSTelemetrySnapshot esqlTelemetrySnapshot
+        CCSTelemetrySnapshot esqlTelemetrySnapshot,
+        ProjectRoutingUsageSnapshot projectRoutingUsageSnapshot
     ) {
         super(node);
         this.nodeInfo = nodeInfo;
@@ -65,6 +73,7 @@ public ClusterStatsNodeResponse(
         this.repositoryUsageStats = Objects.requireNonNull(repositoryUsageStats);
         this.searchCcsMetrics = ccsTelemetrySnapshot;
         this.esqlCcsMetrics = esqlTelemetrySnapshot;
+        this.projectRoutingUsageSnapshot = Objects.requireNonNull(projectRoutingUsageSnapshot);
     }
 
     public NodeInfo nodeInfo() {
@@ -103,6 +112,10 @@ public CCSTelemetrySnapshot getEsqlCcsMetrics() {
         return esqlCcsMetrics;
     }
 
+    public ProjectRoutingUsageSnapshot getProjectRoutingUsageSnapshot() {
+        return projectRoutingUsageSnapshot;
+    }
+
     @Override
     public void writeTo(StreamOutput out) throws IOException {
         super.writeTo(out);
@@ -114,6 +127,9 @@ public void writeTo(StreamOutput out) throws IOException {
         repositoryUsageStats.writeTo(out);
         searchCcsMetrics.writeTo(out);
         esqlCcsMetrics.writeTo(out);
+        if (out.getTransportVersion().supports(PROJECT_ROUTING_USAGE_STATS)) {
+            projectRoutingUsageSnapshot.writeTo(out);
+        }
     }
 
 }

server/src/main/java/org/elasticsearch/action/admin/cluster/stats/ClusterStatsResponse.java

@@ -19,6 +19,7 @@
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.unit.ByteSizeValue;
+import org.elasticsearch.core.Nullable;
 import org.elasticsearch.xcontent.ToXContentFragment;
 import org.elasticsearch.xcontent.XContentBuilder;
 
@@ -38,6 +39,9 @@ public class ClusterStatsResponse extends BaseNodesResponse<ClusterStatsNodeResp
     final RepositoryUsageStats repositoryUsageStats;
     final CCSTelemetrySnapshot ccsMetrics;
     final CCSTelemetrySnapshot esqlMetrics;
+    final ProjectRoutingUsageSnapshot projectRoutingUsageSnapshot;
+    @Nullable
+    final TagsConfigSnapshot tagsConfig;
     final long timestamp;
     final String clusterUUID;
     private final Map<String, RemoteClusterStats> remoteClustersStats;
@@ -56,7 +60,8 @@ public ClusterStatsResponse(
         VersionStats versionStats,
         ClusterSnapshotStats clusterSnapshotStats,
         Map<String, RemoteClusterStats> remoteClustersStats,
-        boolean skipMRT
+        boolean skipMRT,
+        @Nullable TagsConfigSnapshot tagsConfig
     ) {
         super(clusterName, nodes, failures);
         this.clusterUUID = clusterUUID;
@@ -65,6 +70,7 @@ public ClusterStatsResponse(
         indicesStats = new ClusterStatsIndices(nodes, mappingStats, analysisStats, versionStats);
         ccsMetrics = new CCSTelemetrySnapshot(skipMRT == false);
         esqlMetrics = new CCSTelemetrySnapshot(false);
+        projectRoutingUsageSnapshot = new ProjectRoutingUsageSnapshot();
         ClusterHealthStatus status = null;
         for (ClusterStatsNodeResponse response : nodes) {
             // only the master node populates the status
@@ -76,9 +82,11 @@ public ClusterStatsResponse(
         nodes.forEach(node -> {
             ccsMetrics.add(node.getSearchCcsMetrics());
             esqlMetrics.add(node.getEsqlCcsMetrics());
+            projectRoutingUsageSnapshot.add(node.getProjectRoutingUsageSnapshot());
         });
         this.status = status;
         this.clusterSnapshotStats = clusterSnapshotStats;
+        this.tagsConfig = tagsConfig;
 
         this.repositoryUsageStats = nodes.stream()
             .map(ClusterStatsNodeResponse::repositoryUsageStats)
@@ -169,6 +177,20 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
 
         builder.endObject();
 
+        if (tagsConfig != null) {
+            builder.startObject("tags");
+            tagsConfig.toXContent(builder, params);
+            builder.endObject();
+        }
+
+        long totalQueries = projectRoutingUsageSnapshot.getSearchQueriesTotal() + projectRoutingUsageSnapshot.getEsqlQueriesTotal();
+        if (totalQueries > 0) {
+            builder.startObject("project_routing");
+            builder.field("queries", totalQueries);
+            projectRoutingUsageSnapshot.toXContent(builder, params);
+            builder.endObject();
+        }
+
         return builder;
     }
 

server/src/main/java/org/elasticsearch/action/admin/cluster/stats/ClusterStatsTagsProvider.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the "Elastic License
+ * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
+ * Public License v 1"; you may not use this file except in compliance with, at
+ * your election, the "Elastic License 2.0", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+package org.elasticsearch.action.admin.cluster.stats;
+
+import org.elasticsearch.cluster.ClusterState;
+import org.elasticsearch.core.Nullable;
+
+/**
+ * Extension point for supplying the {@code tags} configuration snapshot (tag names, named routing expressions, etc.)
+ * to {@code GET _cluster/stats}. Registered via {@link org.elasticsearch.plugins.ActionPlugin#getClusterStatsTagsProvider()}.
+ *
+ * <p>Needed as an extension point for serverless code.
+ */
+@FunctionalInterface
+public interface ClusterStatsTagsProvider {
+
+    /**
+     * Returns the current tags configuration snapshot for the request's project, or {@code null} if the configuration
+     * is unavailable (e.g. CPS is disabled, or the project cannot be resolved from the thread context).
+     */
+    @Nullable
+    TagsConfigSnapshot getTagsConfig(ClusterState clusterState);
+}

server/src/main/java/org/elasticsearch/action/admin/cluster/stats/ProjectRoutingUsageHolder.java

@@ -0,0 +1,140 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the "Elastic License
+ * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
+ * Public License v 1"; you may not use this file except in compliance with, at
+ * your election, the "Elastic License 2.0", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+package org.elasticsearch.action.admin.cluster.stats;
+
+import org.elasticsearch.core.Nullable;
+import org.elasticsearch.search.crossproject.ProjectRoutingRequestInfo;
+
+import java.util.concurrent.atomic.LongAdder;
+
+/**
+ * Accumulates per-node project-routing telemetry counters. Follows the same pattern as {@link CCSUsageTelemetry}.
+ * Thread-safe via {@link LongAdder}. Obtain a point-in-time snapshot with {@link #getSnapshot()}.
+ *
+ * <p>All counters are gated on {@code hasLinkedProjects}: they only increment while the project has at least one
+ * configured linked project. This ensures percentages can be computed from the data
+ * (e.g. {@code queries_project_routing / queries}).
+ */
+public class ProjectRoutingUsageHolder {
+
+    // _search, _async_search, _msearch (per sub-request), _search/template, _msearch/template
+    private final LongAdder searchQueriesTotal = new LongAdder();
+    private final LongAdder searchWithProjectRouting = new LongAdder();
+    private final LongAdder searchWithAliasOrigin = new LongAdder();
+    private final LongAdder searchWithAliasWildcard = new LongAdder();
+    private final LongAdder searchWithCustomTags = new LongAdder();
+    private final LongAdder searchWithNamedExpression = new LongAdder();
+    private final LongAdder searchProjectRoutingFailures = new LongAdder();
+
+    // ES|QL endpoint
+    private final LongAdder esqlQueriesTotal = new LongAdder();
+    private final LongAdder esqlWithProjectRouting = new LongAdder();
+    private final LongAdder esqlWithAliasOrigin = new LongAdder();
+    private final LongAdder esqlWithAliasWildcard = new LongAdder();
+    private final LongAdder esqlWithCustomTags = new LongAdder();
+    private final LongAdder esqlWithNamedExpression = new LongAdder();
+    private final LongAdder esqlWithSet = new LongAdder();
+    private final LongAdder esqlProjectRoutingFailures = new LongAdder();
+
+    /**
+     * Records a {@code _search} request. {@code queries} is always incremented (subject to the
+     * {@code hasLinkedProjects} gate). The {@code queries_project_routing} counter and its sub-counters are only
+     * incremented when {@code info} is non-null, i.e. the request carried a {@code project_routing} expression.
+     *
+     * @param info routing metadata from the resolver; null when the request had no {@code project_routing} header,
+     *             or until the resolver is upgraded to populate it (Ticket 2)
+     * @param hasLinkedProjects true when the project had at least one linked project at the time of the request;
+     *                          when false all counters are skipped
+     */
+    public void recordSearch(@Nullable ProjectRoutingRequestInfo info, boolean hasLinkedProjects) {
+        if (hasLinkedProjects == false) return;
+        searchQueriesTotal.increment();
+        if (info == null) return;
+        searchWithProjectRouting.increment();
+        if (info.usedAliasOrigin()) searchWithAliasOrigin.increment();
+        if (info.usedAliasWildcard()) searchWithAliasWildcard.increment();
+        if (info.usedNamedExpression()) searchWithNamedExpression.increment();
+        if (info.tagsUsedInRouting().stream().anyMatch(t -> t.startsWith("_") == false)) searchWithCustomTags.increment();
+    }
+
+    /**
+     * Records an ES|QL request. {@code queries} is always incremented (subject to the
+     * {@code hasLinkedProjects} gate). The {@code queries_project_routing} counter and its sub-counters are only
+     * incremented when {@code info} is non-null, i.e. the request carried a {@code project_routing} expression.
+     *
+     * @param info routing metadata from the resolver; null when the request had no {@code project_routing} expression,
+     *             or until the resolver is upgraded to populate it (Ticket 2)
+     * @param setClauseUsed true when the routing expression came from an in-query {@code SET project_routing = ...} clause
+     * @param hasLinkedProjects true when the project had at least one linked project at the time of the request;
+     *                          when false all counters are skipped
+     */
+    public void recordEsql(@Nullable ProjectRoutingRequestInfo info, boolean setClauseUsed, boolean hasLinkedProjects) {
+        if (hasLinkedProjects == false) return;
+        esqlQueriesTotal.increment();
+        if (setClauseUsed) esqlWithSet.increment();
+        if (info == null) return;
+        esqlWithProjectRouting.increment();
+        if (info.usedAliasOrigin()) esqlWithAliasOrigin.increment();
+        if (info.usedAliasWildcard()) esqlWithAliasWildcard.increment();
+        if (info.usedNamedExpression()) esqlWithNamedExpression.increment();
+        if (info.tagsUsedInRouting().stream().anyMatch(t -> t.startsWith("_") == false)) esqlWithCustomTags.increment();
+    }
+
+    /**
+     * Records a routing failure for a {@code _search}-family request. Increments {@code queries},
+     * {@code queries_project_routing}, and {@code failures}. Called by Ticket 5 from
+     * {@code AuthorizationService.onAuthorizedResourceLoadFailure()}.
+     *
+     * @param hasLinkedProjects true when the project had at least one linked project; when false this is a no-op
+     */
+    public void recordSearchProjectRoutingFailure(boolean hasLinkedProjects) {
+        if (hasLinkedProjects == false) return;
+        searchQueriesTotal.increment();
+        searchWithProjectRouting.increment();
+        searchProjectRoutingFailures.increment();
+    }
+
+    /**
+     * Records a routing failure for an ES|QL request. Increments {@code queries},
+     * {@code queries_project_routing}, and {@code failures}. Called by Ticket 5 from
+     * {@code AuthorizationService.onAuthorizedResourceLoadFailure()}.
+     *
+     * @param hasLinkedProjects true when the project had at least one linked project; when false this is a no-op
+     */
+    public void recordEsqlProjectRoutingFailure(boolean hasLinkedProjects) {
+        if (hasLinkedProjects == false) return;
+        esqlQueriesTotal.increment();
+        esqlWithProjectRouting.increment();
+        esqlProjectRoutingFailures.increment();
+    }
+
+    /**
+     * Returns a point-in-time snapshot of the current counters.
+     */
+    public ProjectRoutingUsageSnapshot getSnapshot() {
+        return new ProjectRoutingUsageSnapshot(
+            searchQueriesTotal.sum(),
+            searchWithProjectRouting.sum(),
+            searchWithAliasOrigin.sum(),
+            searchWithAliasWildcard.sum(),
+            searchWithCustomTags.sum(),
+            searchWithNamedExpression.sum(),
+            searchProjectRoutingFailures.sum(),
+            esqlQueriesTotal.sum(),
+            esqlWithProjectRouting.sum(),
+            esqlWithAliasOrigin.sum(),
+            esqlWithAliasWildcard.sum(),
+            esqlWithCustomTags.sum(),
+            esqlWithNamedExpression.sum(),
+            esqlWithSet.sum(),
+            esqlProjectRoutingFailures.sum()
+        );
+    }
+}