Remove es.serverless flag

This commit removes the remaining uses of the es.serverless flag. It is
no longer needed given pluggability of the rest and cat cations.

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

@@ -274,7 +274,6 @@
 import org.elasticsearch.action.update.UpdateAction;
 import org.elasticsearch.client.internal.node.NodeClient;
 import org.elasticsearch.cluster.metadata.IndexNameExpressionResolver;
-import org.elasticsearch.cluster.node.DiscoveryNode;
 import org.elasticsearch.cluster.node.DiscoveryNodes;
 import org.elasticsearch.cluster.service.ClusterService;
 import org.elasticsearch.common.NamedRegistry;
@@ -509,7 +508,6 @@ public class ActionModule extends AbstractModule {
     private final RequestValidators<IndicesAliasesRequest> indicesAliasesRequestRequestValidators;
     private final ThreadPool threadPool;
     private final ReservedClusterStateService reservedClusterStateService;
-    private final boolean serverlessEnabled;
     private final RestExtension restExtension;
 
     public ActionModule(
@@ -536,7 +534,6 @@ public ActionModule(
         this.settingsFilter = settingsFilter;
         this.actionPlugins = actionPlugins;
         this.threadPool = threadPool;
-        this.serverlessEnabled = DiscoveryNode.isServerless();
         actions = setupActions(actionPlugins);
         actionFilters = setupActionFilters(actionPlugins);
         autoCreateIndex = new AutoCreateIndex(settings, clusterSettings, indexNameExpressionResolver, systemIndices);

server/src/main/java/org/elasticsearch/cluster/node/DiscoveryNode.java

@@ -58,16 +58,6 @@ public static boolean isStateless(final Settings settings) {
         return settings.getAsBoolean(STATELESS_ENABLED_SETTING_NAME, false);
     }
 
-    /**
-     * Check if the serverless feature flag is present and set to {@code true}, indicating that the node is
-     * part of a serverless deployment.
-     *
-     * @return true if the serverless feature flag is present and set
-     */
-    public static boolean isServerless() {
-        return DiscoveryNodeRole.hasServerlessFeatureFlag();
-    }
-
     static final String COORDINATING_ONLY = "coordinating_only";
     public static final TransportVersion EXTERNAL_ID_VERSION = TransportVersions.V_8_3_0;
     public static final Comparator<DiscoveryNode> DISCOVERY_NODE_COMPARATOR = Comparator.comparing(DiscoveryNode::getName)

server/src/main/java/org/elasticsearch/cluster/node/DiscoveryNodeRole.java

@@ -8,10 +8,8 @@
 
 package org.elasticsearch.cluster.node;
 
-import org.elasticsearch.Build;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.util.set.Sets;
-import org.elasticsearch.core.Booleans;
 
 import java.lang.reflect.Field;
 import java.util.Arrays;
@@ -28,19 +26,6 @@
  */
 public class DiscoveryNodeRole implements Comparable<DiscoveryNodeRole> {
 
-    /**
-     * A feature flag to indicate if serverless is available or not. Defaults to false.
-     */
-    private static final String USE_SERVERLESS_SYSTEM_PROPERTY = "es.serverless";
-    private static final Boolean USE_SERVERLESS_FEATURE_FLAG;
-    static {
-        final Boolean useStateless = Booleans.parseBoolean(System.getProperty(USE_SERVERLESS_SYSTEM_PROPERTY), false);
-        if (useStateless && Build.current().isSnapshot() == false) {
-            throw new IllegalArgumentException("Enabling serverless usage is only supported in snapshot builds");
-        }
-        USE_SERVERLESS_FEATURE_FLAG = useStateless;
-    }
-
     private final String roleName;
 
     /**
@@ -371,8 +356,4 @@ public static Optional<DiscoveryNodeRole> maybeGetRoleFromRoleName(final String
     public static DiscoveryNodeRole getRoleFromRoleName(final String roleName) {
         return maybeGetRoleFromRoleName(roleName).orElseThrow(() -> new IllegalArgumentException("unknown role [" + roleName + "]"));
     }
-
-    public static boolean hasServerlessFeatureFlag() {
-        return USE_SERVERLESS_FEATURE_FLAG;
-    }
 }

x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/Security.java

@@ -910,8 +910,7 @@ Collection<Object> createComponents(
 
         final AuthenticationFailureHandler failureHandler = createAuthenticationFailureHandler(realms, extensionComponents);
 
-        // operator privileges are enabled either explicitly via the setting or if running serverless
-        final boolean operatorPrivilegesEnabled = OPERATOR_PRIVILEGES_ENABLED.get(settings) || DiscoveryNode.isServerless();
+        final boolean operatorPrivilegesEnabled = OPERATOR_PRIVILEGES_ENABLED.get(settings);
 
         if (operatorPrivilegesEnabled) {
             logger.info("operator privileges are enabled");

x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/SecurityTests.java

@@ -924,7 +924,6 @@ public <T> List<T> loadExtensions(Class<T> extensionPointType) {
     }
 
     public void testLoadExtensionsWhenOperatorPrivsAreDisabled() throws Exception {
-        assumeFalse("feature flag for serverless is expected to be false", DiscoveryNode.isServerless());
         Settings.Builder settingsBuilder = Settings.builder().put("xpack.security.enabled", true).put("path.home", createTempDir());
 
         if (randomBoolean()) {
@@ -951,36 +950,6 @@ public <T> List<T> loadExtensions(Class<T> extensionPointType) {
         assertThat(operatorPrivilegesService, is(NOOP_OPERATOR_PRIVILEGES_SERVICE));
     }
 
-    public void testLoadExtensionsWhenOperatorPrivsAreDisabledAndServerless() throws Exception {
-        assumeTrue("feature flag for serverless is expected to be true", DiscoveryNode.isServerless());
-        Settings.Builder settingsBuilder = Settings.builder().put("xpack.security.enabled", true).put("path.home", createTempDir());
-
-        if (randomBoolean()) {
-            settingsBuilder.put(OPERATOR_PRIVILEGES_ENABLED.getKey(), false); // doesn't matter if explicit or implicitly disabled
-        }
-
-        Settings settings = settingsBuilder.build();
-        constructNewSecurityObject(settings);
-        security.loadExtensions(new ExtensiblePlugin.ExtensionLoader() {
-            @Override
-            @SuppressWarnings("unchecked")
-            public <T> List<T> loadExtensions(Class<T> extensionPointType) {
-                List<Object> extensions = new ArrayList<>();
-                if (extensionPointType == OperatorOnlyRegistry.class) {
-                    if (randomBoolean()) {
-                        extensions.add(new DummyOperatorOnlyRegistry()); // will be used
-                    }
-                }
-                return (List<T>) extensions;
-            }
-        });
-        createComponentsUtil(settings);
-        OperatorPrivileges.OperatorPrivilegesService operatorPrivilegesService = security.getOperatorPrivilegesService();
-        OperatorOnlyRegistry registry = ((OperatorPrivileges.DefaultOperatorPrivilegesService) operatorPrivilegesService)
-            .getOperatorOnlyRegistry();
-        assertThat(registry, instanceOf(DummyOperatorOnlyRegistry.class));
-    }
-
     private void verifyHasAuthenticationHeaderValue(Exception e, String... expectedValues) {
         assertThat(e, instanceOf(ElasticsearchSecurityException.class));
         assertThat(((ElasticsearchSecurityException) e).getHeader("WWW-Authenticate"), notNullValue());