[Backport 2.x] [Extensions] Add ExtensionAwarePlugin extension point to add custom settings for extensions (#7526)

CHANGELOG.md

@@ -24,6 +24,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Create NamedRoute to map extension routes to a shortened name ([#6870](https://github.com/opensearch-project/OpenSearch/pull/6870))
 - Added @dbwiddis as on OpenSearch maintainer ([#7665](https://github.com/opensearch-project/OpenSearch/pull/7665))
 - SegRep with Remote: Add hook for publishing checkpoint notifications after segment upload to remote store ([#7394](https://github.com/opensearch-project/OpenSearch/pull/7394))
+- [Extensions] Add ExtensionAwarePlugin extension point to add custom settings for extensions ([#7526](https://github.com/opensearch-project/OpenSearch/pull/7526))
 
 ### Dependencies
 - Bump `com.netflix.nebula:gradle-info-plugin` from 12.0.0 to 12.1.3 (#7564)

server/src/main/java/org/opensearch/common/settings/Setting.java

@@ -132,6 +132,11 @@ public enum Property {
          */
         Deprecated,
 
+        /**
+         * Extension scope
+         */
+        ExtensionScope,
+
         /**
          * Node scope
          */

server/src/main/java/org/opensearch/extensions/ExtensionScopedSettings.java

@@ -0,0 +1,34 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.extensions;
+
+import org.opensearch.common.settings.AbstractScopedSettings;
+import org.opensearch.common.settings.Setting;
+import org.opensearch.common.settings.Setting.Property;
+import org.opensearch.common.settings.SettingUpgrader;
+import org.opensearch.common.settings.Settings;
+
+import java.util.Collections;
+import java.util.Set;
+
+/**
+ * Encapsulates all valid extension level settings.
+ *
+ * @opensearch.internal
+ */
+public final class ExtensionScopedSettings extends AbstractScopedSettings {
+
+    public ExtensionScopedSettings(final Set<Setting<?>> settingsSet) {
+        this(settingsSet, Collections.emptySet());
+    }
+
+    public ExtensionScopedSettings(final Set<Setting<?>> settingsSet, final Set<SettingUpgrader<?>> settingUpgraders) {
+        super(Settings.EMPTY, settingsSet, settingUpgraders, Property.ExtensionScope);
+    }
+}

server/src/main/java/org/opensearch/extensions/ExtensionsManager.java

@@ -14,11 +14,14 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
+import java.util.Set;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CompletionException;
 import java.util.concurrent.TimeUnit;
@@ -37,6 +40,7 @@
 import org.opensearch.cluster.ClusterSettingsResponse;
 import org.opensearch.cluster.service.ClusterService;
 import org.opensearch.common.io.FileSystemUtils;
+import org.opensearch.common.settings.Setting;
 import org.opensearch.common.io.stream.StreamInput;
 import org.opensearch.common.settings.Settings;
 import org.opensearch.common.settings.SettingsModule;
@@ -105,6 +109,7 @@ public static enum OpenSearchRequestType {
     private CustomSettingsRequestHandler customSettingsRequestHandler;
     private TransportService transportService;
     private ClusterService clusterService;
+    private final Set<Setting<?>> additionalSettings;
     private Settings environmentSettings;
     private AddSettingsUpdateConsumerRequestHandler addSettingsUpdateConsumerRequestHandler;
     private NodeClient client;
@@ -113,9 +118,10 @@ public static enum OpenSearchRequestType {
      * Instantiate a new ExtensionsManager object to handle requests and responses from extensions. This is called during Node bootstrap.
      *
      * @param extensionsPath  Path to a directory containing extensions.
+     * @param additionalSettings  Additional settings to read in from extensions.yml
      * @throws IOException  If the extensions discovery file is not properly retrieved.
      */
-    public ExtensionsManager(Path extensionsPath) throws IOException {
+    public ExtensionsManager(Path extensionsPath, Set<Setting<?>> additionalSettings) throws IOException {
         logger.info("ExtensionsManager initialized");
         this.extensionsPath = extensionsPath;
         this.initializedExtensions = new HashMap<String, DiscoveryExtensionNode>();
@@ -124,6 +130,11 @@ public ExtensionsManager(Path extensionsPath) throws IOException {
         // will be initialized in initializeServicesAndRestHandler which is called after the Node is initialized
         this.transportService = null;
         this.clusterService = null;
+        // Settings added to extensions.yml by ExtensionAwarePlugins, such as security settings
+        this.additionalSettings = new HashSet<>();
+        if (additionalSettings != null) {
+            this.additionalSettings.addAll(additionalSettings);
+        }
         this.client = null;
         this.extensionTransportActionsHandler = null;
 
@@ -465,35 +476,68 @@ private ExtensionsSettings readFromExtensionsYml(Path filePath) throws IOExcepti
             }
             List<HashMap<String, ?>> unreadExtensions = new ArrayList<>((Collection<HashMap<String, ?>>) obj.get("extensions"));
             List<Extension> readExtensions = new ArrayList<Extension>();
+            Set<String> additionalSettingsKeys = additionalSettings.stream().map(s -> s.getKey()).collect(Collectors.toSet());
             for (HashMap<String, ?> extensionMap : unreadExtensions) {
-                // Parse extension dependencies
-                List<ExtensionDependency> extensionDependencyList = new ArrayList<ExtensionDependency>();
-                if (extensionMap.get("dependencies") != null) {
-                    List<HashMap<String, ?>> extensionDependencies = new ArrayList<>(
-                        (Collection<HashMap<String, ?>>) extensionMap.get("dependencies")
-                    );
-                    for (HashMap<String, ?> dependency : extensionDependencies) {
-                        extensionDependencyList.add(
-                            new ExtensionDependency(
-                                dependency.get("uniqueId").toString(),
-                                Version.fromString(dependency.get("version").toString())
-                            )
+                try {
+                    // checking to see whether any required fields are missing from extension.yml file or not
+                    String[] requiredFields = {
+                        "name",
+                        "uniqueId",
+                        "hostAddress",
+                        "port",
+                        "version",
+                        "opensearchVersion",
+                        "minimumCompatibleVersion" };
+                    List<String> missingFields = Arrays.stream(requiredFields)
+                        .filter(field -> !extensionMap.containsKey(field))
+                        .collect(Collectors.toList());
+                    if (!missingFields.isEmpty()) {
+                        throw new IOException("Extension is missing these required fields : " + missingFields);
+                    }
+
+                    // Parse extension dependencies
+                    List<ExtensionDependency> extensionDependencyList = new ArrayList<ExtensionDependency>();
+                    if (extensionMap.get("dependencies") != null) {
+                        List<HashMap<String, ?>> extensionDependencies = new ArrayList<>(
+                            (Collection<HashMap<String, ?>>) extensionMap.get("dependencies")
                         );
+                        for (HashMap<String, ?> dependency : extensionDependencies) {
+                            extensionDependencyList.add(
+                                new ExtensionDependency(
+                                    dependency.get("uniqueId").toString(),
+                                    Version.fromString(dependency.get("version").toString())
+                                )
+                            );
+                        }
                     }
+
+                    ExtensionScopedSettings extAdditionalSettings = new ExtensionScopedSettings(additionalSettings);
+                    Map<String, ?> additionalSettingsMap = extensionMap.entrySet()
+                        .stream()
+                        .filter(kv -> additionalSettingsKeys.contains(kv.getKey()))
+                        .collect(Collectors.toMap(map -> map.getKey(), map -> map.getValue()));
+
+                    Settings.Builder output = Settings.builder();
+                    output.loadFromMap(additionalSettingsMap);
+                    extAdditionalSettings.applySettings(output.build());
+
+                    // Create extension read from yml config
+                    readExtensions.add(
+                        new Extension(
+                            extensionMap.get("name").toString(),
+                            extensionMap.get("uniqueId").toString(),
+                            extensionMap.get("hostAddress").toString(),
+                            extensionMap.get("port").toString(),
+                            extensionMap.get("version").toString(),
+                            extensionMap.get("opensearchVersion").toString(),
+                            extensionMap.get("minimumCompatibleVersion").toString(),
+                            extensionDependencyList,
+                            extAdditionalSettings
+                        )
+                    );
+                } catch (IOException e) {
+                    logger.warn("loading extension has been failed because of exception : " + e.getMessage());
                 }
-                // Create extension read from yml config
-                readExtensions.add(
-                    new Extension(
-                        extensionMap.get("name").toString(),
-                        extensionMap.get("uniqueId").toString(),
-                        extensionMap.get("hostAddress").toString(),
-                        extensionMap.get("port").toString(),
-                        extensionMap.get("version").toString(),
-                        extensionMap.get("opensearchVersion").toString(),
-                        extensionMap.get("minimumCompatibleVersion").toString(),
-                        extensionDependencyList
-                    )
-                );
             }
             inputStream.close();
             return new ExtensionsSettings(readExtensions);

server/src/main/java/org/opensearch/extensions/ExtensionsSettings.java

@@ -44,6 +44,7 @@ public static class Extension {
         private String opensearchVersion;
         private String minimumCompatibleVersion;
         private List<ExtensionDependency> dependencies = Collections.emptyList();
+        private ExtensionScopedSettings additionalSettings;
 
         public Extension(
             String name,
@@ -53,7 +54,8 @@ public Extension(
             String version,
             String opensearchVersion,
             String minimumCompatibleVersion,
-            List<ExtensionDependency> dependencies
+            List<ExtensionDependency> dependencies,
+            ExtensionScopedSettings additionalSettings
         ) {
             this.name = name;
             this.uniqueId = uniqueId;
@@ -63,6 +65,7 @@ public Extension(
             this.opensearchVersion = opensearchVersion;
             this.minimumCompatibleVersion = minimumCompatibleVersion;
             this.dependencies = dependencies;
+            this.additionalSettings = additionalSettings;
         }
 
         public Extension() {
@@ -127,6 +130,10 @@ public List<ExtensionDependency> getDependencies() {
             return dependencies;
         }
 
+        public ExtensionScopedSettings getAdditionalSettings() {
+            return additionalSettings;
+        }
+
         public String getMinimumCompatibleVersion() {
             return minimumCompatibleVersion;
         }

server/src/main/java/org/opensearch/extensions/NoopExtensionsManager.java

@@ -11,6 +11,7 @@
 import java.io.IOException;
 import java.nio.file.Path;
 import java.util.Optional;
+import java.util.Set;
 
 import org.opensearch.action.ActionModule;
 import org.opensearch.client.node.NodeClient;
@@ -31,7 +32,7 @@
 public class NoopExtensionsManager extends ExtensionsManager {
 
     public NoopExtensionsManager() throws IOException {
-        super(Path.of(""));
+        super(Path.of(""), Set.of());
     }
 
     @Override

server/src/main/java/org/opensearch/node/Node.java

@@ -56,6 +56,7 @@
 import org.opensearch.extensions.NoopExtensionsManager;
 import org.opensearch.monitor.fs.FsInfo;
 import org.opensearch.monitor.fs.FsProbe;
+import org.opensearch.plugins.ExtensionAwarePlugin;
 import org.opensearch.plugins.SearchPipelinePlugin;
 import org.opensearch.search.backpressure.SearchBackpressureService;
 import org.opensearch.search.backpressure.settings.SearchBackpressureSettings;
@@ -236,6 +237,7 @@
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
@@ -468,7 +470,12 @@ protected Node(
             final IdentityService identityService = new IdentityService(settings, identityPlugins);
 
             if (FeatureFlags.isEnabled(FeatureFlags.EXTENSIONS)) {
-                this.extensionsManager = new ExtensionsManager(initialEnvironment.extensionDir());
+                final List<ExtensionAwarePlugin> extensionAwarePlugins = pluginsService.filterPlugins(ExtensionAwarePlugin.class);
+                Set<Setting<?>> additionalSettings = new HashSet<>();
+                for (ExtensionAwarePlugin extAwarePlugin : extensionAwarePlugins) {
+                    additionalSettings.addAll(extAwarePlugin.getExtensionSettings());
+                }
+                this.extensionsManager = new ExtensionsManager(initialEnvironment.extensionDir(), additionalSettings);
             } else {
                 this.extensionsManager = new NoopExtensionsManager();
             }

server/src/main/java/org/opensearch/plugins/ExtensionAwarePlugin.java

@@ -0,0 +1,29 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.plugins;
+
+import org.opensearch.common.settings.Setting;
+
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * Plugin that provides extra settings for extensions
+ *
+ * @opensearch.experimental
+ */
+public interface ExtensionAwarePlugin {
+
+    /**
+     * Returns a list of additional {@link Setting} definitions that this plugin adds for extensions
+     */
+    default List<Setting<?>> getExtensionSettings() {
+        return Collections.emptyList();
+    }
+}

server/src/main/java/org/opensearch/plugins/IdentityPlugin.java

@@ -22,5 +22,5 @@ public interface IdentityPlugin {
      *
      * Should never return null
      * */
-    public Subject getSubject();
+    Subject getSubject();
 }