elastic · alexey-ivanov-es · Apr 23, 2025 · Apr 23, 2025 · Apr 23, 2025 · Apr 23, 2025
diff --git a/docs/changelog/127252.yaml b/docs/changelog/127252.yaml
@@ -0,0 +1,5 @@
+pr: 127252
+summary: New per-project only settings can be defined and used by components
+area: Infra/Settings
+type: feature
+issues: []
diff --git a/server/src/main/java/org/elasticsearch/TransportVersions.java b/server/src/main/java/org/elasticsearch/TransportVersions.java
@@ -226,6 +226,7 @@ static TransportVersion def(int id) {
     public static final TransportVersion SYNONYMS_REFRESH_PARAM = def(9_060_0_00);
     public static final TransportVersion DOC_FIELDS_AS_LIST = def(9_061_0_00);
     public static final TransportVersion DENSE_VECTOR_OFF_HEAP_STATS = def(9_062_00_0);
+    public static final TransportVersion PROJECT_METADATA_SETTINGS = def(9_063_00_0);
 
     /*
      * STOP! READ THIS FIRST! No, really,

diff --git a/server/src/main/java/org/elasticsearch/cluster/metadata/Metadata.java b/server/src/main/java/org/elasticsearch/cluster/metadata/Metadata.java
@@ -950,7 +950,13 @@ private MetadataDiff(StreamInput in) throws IOException {
                     RESERVED_DIFF_VALUE_READER
                 );
 
-                singleProject = new ProjectMetadata.ProjectMetadataDiff(indices, templates, projectCustoms, DiffableUtils.emptyDiff());
+                singleProject = new ProjectMetadata.ProjectMetadataDiff(
+                    indices,
+                    templates,
+                    projectCustoms,
+                    DiffableUtils.emptyDiff(),
+                    Settings.EMPTY_DIFF
+                );
                 multiProject = null;
             } else {
                 fromNodeBeforeMultiProjectsSupport = false;

diff --git a/server/src/main/java/org/elasticsearch/cluster/metadata/ProjectMetadata.java b/server/src/main/java/org/elasticsearch/cluster/metadata/ProjectMetadata.java
@@ -102,6 +102,8 @@ public class ProjectMetadata implements Iterable<IndexMetadata>, Diffable<Projec
     private volatile SortedMap<String, IndexAbstraction> indicesLookup;
     private final Map<String, MappingMetadata> mappingsByHash;
 
+    private final Settings settings;
+
     private final IndexVersion oldestIndexVersion;
 
     @SuppressWarnings("this-escape")
@@ -122,6 +124,7 @@ private ProjectMetadata(
         String[] visibleClosedIndices,
         SortedMap<String, IndexAbstraction> indicesLookup,
         Map<String, MappingMetadata> mappingsByHash,
+        Settings settings,
         IndexVersion oldestIndexVersion
     ) {
         this.id = id;
@@ -140,6 +143,7 @@ private ProjectMetadata(
         this.visibleClosedIndices = visibleClosedIndices;
         this.indicesLookup = indicesLookup;
         this.mappingsByHash = mappingsByHash;
+        this.settings = settings;
         this.oldestIndexVersion = oldestIndexVersion;
         assert assertConsistent();
     }
@@ -221,6 +225,7 @@ public ProjectMetadata withLifecycleState(Index index, LifecycleExecutionState l
             visibleClosedIndices,
             indicesLookup,
             mappingsByHash,
+            settings,
             oldestIndexVersion
         );
     }
@@ -254,6 +259,7 @@ public ProjectMetadata withIndexSettingsUpdates(Map<Index, Settings> updates) {
             visibleClosedIndices,
             indicesLookup,
             mappingsByHash,
+            settings,
             oldestIndexVersion
         );
     }
@@ -288,6 +294,7 @@ public ProjectMetadata withAllocationAndTermUpdatesOnly(Map<String, IndexMetadat
             visibleClosedIndices,
             indicesLookup,
             mappingsByHash,
+            settings,
             oldestIndexVersion
         );
     }
@@ -376,6 +383,7 @@ public ProjectMetadata withAddedIndex(IndexMetadata index) {
             updatedVisibleClosedIndices,
             null,
             updatedMappingsByHash,
+            settings,
             IndexVersion.min(index.getCompatibilityVersion(), oldestIndexVersion)
         );
     }
@@ -727,6 +735,10 @@ public Map<String, IndexTemplateMetadata> templates() {
         return templates;
     }
 
+    public Settings settings() {
+        return settings;
+    }
+
     /**
      * Checks whether the provided index is a data stream.
      */
@@ -1130,6 +1142,7 @@ public static class Builder {
         private final ImmutableOpenMap.Builder<String, IndexTemplateMetadata> templates;
         private final ImmutableOpenMap.Builder<String, Metadata.ProjectCustom> customs;
         private final ImmutableOpenMap.Builder<String, ReservedStateMetadata> reservedStateMetadata;
+        private Settings settings = Settings.EMPTY;
 
         private SortedMap<String, IndexAbstraction> previousIndicesLookup;
 
@@ -1147,6 +1160,7 @@ public static class Builder {
             this.templates = ImmutableOpenMap.builder(projectMetadata.templates);
             this.customs = ImmutableOpenMap.builder(projectMetadata.customs);
             this.reservedStateMetadata = ImmutableOpenMap.builder(projectMetadata.reservedStateMetadata);
+            this.settings = projectMetadata.settings;
             this.previousIndicesLookup = projectMetadata.indicesLookup;
             this.mappingsByHash = new HashMap<>(projectMetadata.mappingsByHash);
             this.checkForUnusedMappings = false;
@@ -1525,6 +1539,15 @@ public Builder removeReservedState(ReservedStateMetadata metadata) {
             return this;
         }
 
+        public Settings settings() {
+            return this.settings;
+        }
+
+        public ProjectMetadata.Builder settings(Settings settings) {
+            this.settings = settings;
+            return this;
+        }
+
         public Builder indexGraveyard(final IndexGraveyard indexGraveyard) {
             return putCustom(IndexGraveyard.TYPE, indexGraveyard);
         }
@@ -1684,6 +1707,7 @@ public ProjectMetadata build(boolean skipNameCollisionChecks) {
                 visibleClosedIndicesArray,
                 indicesLookup,
                 Collections.unmodifiableMap(mappingsByHash),
+                settings,
                 IndexVersion.fromId(oldestIndexVersionId)
             );
         }
@@ -2110,6 +2134,9 @@ public static ProjectMetadata fromXContent(XContentParser parser) throws IOExcep
                                 projectBuilder.put(IndexTemplateMetadata.Builder.fromXContent(parser, parser.currentName()));
                             }
                         }
+                        case "settings" -> {
+                            projectBuilder.settings(Settings.fromXContent(parser));
+                        }
                         default -> Metadata.Builder.parseCustomObject(
                             parser,
                             currentFieldName,
@@ -2157,7 +2184,8 @@ public Iterator<? extends ToXContent> toXContentChunked(ToXContent.Params p) {
             customs,
             multiProject
                 ? ChunkedToXContentHelper.object("reserved_state", reservedStateMetadata().values().iterator())
-                : Collections.emptyIterator()
+                : Collections.emptyIterator(),
+            multiProject ? ChunkedToXContentHelper.object("settings", Iterators.single(settings)) : Collections.emptyIterator()
         );
     }
 
@@ -2189,6 +2217,10 @@ public static ProjectMetadata readFrom(StreamInput in) throws IOException {
             builder.put(ReservedStateMetadata.readFrom(in));
         }
 
+        if (in.getTransportVersion().onOrAfter(TransportVersions.PROJECT_METADATA_SETTINGS)) {
+            builder.settings(Settings.readSettingsFromStream(in));
+        }
+
         return builder.build();
     }
 
@@ -2229,6 +2261,10 @@ public void writeTo(StreamOutput out) throws IOException {
         }
         VersionedNamedWriteable.writeVersionedWriteables(out, filteredCustoms);
         out.writeCollection(reservedStateMetadata.values());
+
+        if (out.getTransportVersion().onOrAfter(TransportVersions.PROJECT_METADATA_SETTINGS)) {
+            settings.writeTo(out);
+        }
     }
 
     // this needs to be package accessible for bwc serialization in Metadata.java
@@ -2248,13 +2284,15 @@ static class ProjectMetadataDiff implements Diff<ProjectMetadata> {
             String,
             ReservedStateMetadata,
             ImmutableOpenMap<String, ReservedStateMetadata>> reservedStateMetadata;
+        private final Diff<Settings> settingsDiff;
 
         private ProjectMetadataDiff(ProjectMetadata before, ProjectMetadata after) {
             if (before == after) {
                 indices = DiffableUtils.emptyDiff();
                 templates = DiffableUtils.emptyDiff();
                 customs = DiffableUtils.emptyDiff();
                 reservedStateMetadata = DiffableUtils.emptyDiff();
+                settingsDiff = Settings.EMPTY_DIFF;
             } else {
                 indices = DiffableUtils.diff(before.indices, after.indices, DiffableUtils.getStringKeySerializer());
                 templates = DiffableUtils.diff(before.templates, after.templates, DiffableUtils.getStringKeySerializer());
@@ -2269,19 +2307,22 @@ private ProjectMetadataDiff(ProjectMetadata before, ProjectMetadata after) {
                     after.reservedStateMetadata,
                     DiffableUtils.getStringKeySerializer()
                 );
+                settingsDiff = after.settings.diff(before.settings);
             }
         }
 
         ProjectMetadataDiff(
             DiffableUtils.MapDiff<String, IndexMetadata, ImmutableOpenMap<String, IndexMetadata>> indices,
             DiffableUtils.MapDiff<String, IndexTemplateMetadata, ImmutableOpenMap<String, IndexTemplateMetadata>> templates,
             DiffableUtils.MapDiff<String, Metadata.ProjectCustom, ImmutableOpenMap<String, Metadata.ProjectCustom>> customs,
-            DiffableUtils.MapDiff<String, ReservedStateMetadata, ImmutableOpenMap<String, ReservedStateMetadata>> reservedStateMetadata
+            DiffableUtils.MapDiff<String, ReservedStateMetadata, ImmutableOpenMap<String, ReservedStateMetadata>> reservedStateMetadata,
+            Diff<Settings> settingsDiff
         ) {
             this.indices = indices;
             this.templates = templates;
             this.customs = customs;
             this.reservedStateMetadata = reservedStateMetadata;
+            this.settingsDiff = settingsDiff;
         }
 
         ProjectMetadataDiff(StreamInput in) throws IOException {
@@ -2293,6 +2334,11 @@ private ProjectMetadataDiff(ProjectMetadata before, ProjectMetadata after) {
                 DiffableUtils.getStringKeySerializer(),
                 RESERVED_DIFF_VALUE_READER
             );
+            if (in.getTransportVersion().onOrAfter(TransportVersions.PROJECT_METADATA_SETTINGS)) {
+                settingsDiff = Settings.readSettingsDiffFromStream(in);
+            } else {
+                settingsDiff = Settings.EMPTY_DIFF;
+            }
         }
 
         Diff<ImmutableOpenMap<String, IndexMetadata>> indices() {
@@ -2317,11 +2363,18 @@ public void writeTo(StreamOutput out) throws IOException {
             templates.writeTo(out);
             customs.writeTo(out);
             reservedStateMetadata.writeTo(out);
+            if (out.getTransportVersion().onOrAfter(TransportVersions.PROJECT_METADATA_SETTINGS)) {
+                settingsDiff.writeTo(out);
+            }
         }
 
         @Override
         public ProjectMetadata apply(ProjectMetadata part) {
-            if (indices.isEmpty() && templates.isEmpty() && customs.isEmpty() && reservedStateMetadata.isEmpty()) {
+            if (indices.isEmpty()
+                && templates.isEmpty()
+                && customs.isEmpty()
+                && reservedStateMetadata.isEmpty()
+                && settingsDiff == Settings.EMPTY_DIFF) {
                 // nothing to do
                 return part;
             }
@@ -2336,13 +2389,14 @@ public ProjectMetadata apply(ProjectMetadata part) {
                 && builder.dataStreamMetadata() == part.custom(DataStreamMetadata.TYPE, DataStreamMetadata.EMPTY)) {
                 builder.previousIndicesLookup = part.indicesLookup;
             }
+            builder.settings = settingsDiff.apply(builder.settings);
             return builder.build(true);
         }
 
         ProjectMetadataDiff withCustoms(
             DiffableUtils.MapDiff<String, Metadata.ProjectCustom, ImmutableOpenMap<String, Metadata.ProjectCustom>> customs
         ) {
-            return new ProjectMetadataDiff(indices, templates, customs, reservedStateMetadata);
+            return new ProjectMetadataDiff(indices, templates, customs, reservedStateMetadata, settingsDiff);
         }
     }
 

diff --git a/server/src/main/java/org/elasticsearch/cluster/service/ClusterService.java b/server/src/main/java/org/elasticsearch/cluster/service/ClusterService.java
@@ -23,6 +23,7 @@
 import org.elasticsearch.common.Priority;
 import org.elasticsearch.common.component.AbstractLifecycleComponent;
 import org.elasticsearch.common.settings.ClusterSettings;
+import org.elasticsearch.common.settings.ProjectScopedSettings;
 import org.elasticsearch.common.settings.Setting;
 import org.elasticsearch.common.settings.Setting.Property;
 import org.elasticsearch.common.settings.Settings;
@@ -31,6 +32,8 @@
 import org.elasticsearch.tasks.TaskManager;
 import org.elasticsearch.threadpool.ThreadPool;
 
+import java.util.Collections;
+
 public class ClusterService extends AbstractLifecycleComponent {
     private final MasterService masterService;
 
@@ -52,12 +55,31 @@ public class ClusterService extends AbstractLifecycleComponent {
 
     private final ClusterSettings clusterSettings;
 
+    private final ProjectScopedSettings projectScopedSettings;
+
     private final String nodeName;
 
     public ClusterService(Settings settings, ClusterSettings clusterSettings, ThreadPool threadPool, TaskManager taskManager) {
         this(
             settings,
             clusterSettings,
+            new ProjectScopedSettings(settings, Collections.emptySet()),
+            new MasterService(settings, clusterSettings, threadPool, taskManager),
+            new ClusterApplierService(Node.NODE_NAME_SETTING.get(settings), settings, clusterSettings, threadPool)
+        );
+    }
+
+    public ClusterService(
+        Settings settings,
+        ClusterSettings clusterSettings,
+        ProjectScopedSettings projectScopedSettings,
+        ThreadPool threadPool,
+        TaskManager taskManager
+    ) {
+        this(
+            settings,
+            clusterSettings,
+            projectScopedSettings,
             new MasterService(settings, clusterSettings, threadPool, taskManager),
             new ClusterApplierService(Node.NODE_NAME_SETTING.get(settings), settings, clusterSettings, threadPool)
         );
@@ -68,10 +90,21 @@ public ClusterService(
         ClusterSettings clusterSettings,
         MasterService masterService,
         ClusterApplierService clusterApplierService
+    ) {
+        this(settings, clusterSettings, new ProjectScopedSettings(settings, Collections.emptySet()), masterService, clusterApplierService);
+    }
+
+    public ClusterService(
+        Settings settings,
+        ClusterSettings clusterSettings,
+        ProjectScopedSettings projectScopedSettings,
+        MasterService masterService,
+        ClusterApplierService clusterApplierService
     ) {
         this.settings = settings;
         this.nodeName = Node.NODE_NAME_SETTING.get(settings);
         this.masterService = masterService;
+        this.projectScopedSettings = projectScopedSettings;
         this.operationRouting = new OperationRouting(settings, clusterSettings);
         this.clusterSettings = clusterSettings;
         this.clusterName = ClusterName.CLUSTER_NAME_SETTING.get(settings);
@@ -201,6 +234,10 @@ public ClusterSettings getClusterSettings() {
         return clusterSettings;
     }
 
+    public ProjectScopedSettings getProjectScopedSettings() {
+        return projectScopedSettings;
+    }
+
     /**
      * The node's settings.
      */

@@ -0,0 +1,18 @@
+/*
+ * 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.common.settings;
+
+import java.util.Set;
+
+public class ProjectScopedSettings extends AbstractScopedSettings {
+    public ProjectScopedSettings(Settings settings, Set<Setting<?>> settingsSet) {
+        super(settings, settingsSet, Setting.Property.ProjectScope);
+    }
+}
@@ -179,7 +179,12 @@ public enum Property {
          * All other settings will be rejected when used on a PUT request
          * and filtered out on a GET
          */
-        ServerlessPublic
+        ServerlessPublic,
+
+        /**
+         * Project-level file-level setting. Not an index setting.
+         */
+        ProjectScope
     }
 
     private final Key key;

@@ -79,6 +79,7 @@
 public final class Settings implements ToXContentFragment, Writeable, Diffable<Settings> {
 
     public static final Settings EMPTY = new Settings(Map.of(), null);
+    public static final Diff<Settings> EMPTY_DIFF = new SettingsDiff(DiffableUtils.emptyDiff());
 
     public static final String FLAT_SETTINGS_PARAM = "flat_settings";