[8.19] Reserved state removal hooks (elastic#136721) (elastic#137919)

* Reserved state removal hooks (elastic#136721)

* [CI] Auto commit changes from spotless

---------

Co-authored-by: elasticsearchmachine <[email protected]>

Author: prdoyle

server/src/main/java/org/elasticsearch/action/admin/cluster/repositories/reservedstate/ReservedRepositoryAction.java

@@ -91,6 +91,11 @@ public TransformState transform(Object source, TransformState prevState) throws
 
     }
 
+    @Override
+    public ClusterState remove(TransformState prevState) throws Exception {
+        return transform(List.of(), prevState).state();
+    }
+
     @Override
     public List<PutRepositoryRequest> fromXContent(XContentParser parser) throws IOException {
         List<PutRepositoryRequest> result = new ArrayList<>();

server/src/main/java/org/elasticsearch/action/admin/indices/template/reservedstate/ReservedComposableIndexTemplateAction.java

@@ -195,6 +195,11 @@ public TransformState transform(Object source, TransformState prevState) throws
         return new TransformState(state, Sets.union(componentEntities, composableEntities));
     }
 
+    @Override
+    public ClusterState remove(TransformState prevState) throws Exception {
+        return transform(ComponentsAndComposables.EMPTY, prevState).state();
+    }
+
     @Override
     public ComponentsAndComposables fromXContent(XContentParser parser) throws IOException {
         List<PutComponentTemplateAction.Request> componentTemplates = new ArrayList<>();
@@ -237,5 +242,7 @@ public ComponentsAndComposables fromXContent(XContentParser parser) throws IOExc
     record ComponentsAndComposables(
         List<PutComponentTemplateAction.Request> componentTemplates,
         List<TransportPutComposableIndexTemplateAction.Request> composableTemplates
-    ) {}
+    ) {
+        static final ComponentsAndComposables EMPTY = new ComponentsAndComposables(List.of(), List.of());
+    }
 }

server/src/main/java/org/elasticsearch/action/ingest/ReservedPipelineAction.java

@@ -108,6 +108,11 @@ public TransformState transform(Object source, TransformState prevState) throws
         return new TransformState(state, entities);
     }
 
+    @Override
+    public ClusterState remove(TransformState prevState) throws Exception {
+        return transform(List.of(), prevState).state();
+    }
+
     @Override
     public List<PutPipelineRequest> fromXContent(XContentParser parser) throws IOException {
         List<PutPipelineRequest> result = new ArrayList<>();

server/src/main/java/org/elasticsearch/reservedstate/ReservedClusterStateHandler.java

@@ -11,6 +11,7 @@
 
 import org.elasticsearch.action.ActionRequestValidationException;
 import org.elasticsearch.action.support.master.MasterNodeRequest;
+import org.elasticsearch.cluster.ClusterState;
 import org.elasticsearch.core.TimeValue;
 import org.elasticsearch.xcontent.XContentParser;
 
@@ -62,6 +63,19 @@ public interface ReservedClusterStateHandler<T> {
      */
     TransformState transform(Object source, TransformState prevState) throws Exception;
 
+    /**
+     * Called when the source no longer contains a section corresponding to {@link #name}.
+     * A bit like {@link #transform}, but with no {@code source} because the "source" has disappeared,
+     * and no {@link TransformState#keys() keys} in the return value because there aren't any.
+     *
+     * <p>
+     * The intent is to "cancel the reservation" and return the configuration to the state
+     * it would have had if the section had never existed.
+     *
+     * @throws IOException
+     */
+    ClusterState remove(TransformState prevState) throws Exception;
+
     /**
      * List of dependent handler names for this handler.
      *

server/src/main/java/org/elasticsearch/reservedstate/action/ReservedClusterSettingsAction.java

@@ -12,6 +12,7 @@
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.elasticsearch.action.admin.cluster.settings.ClusterUpdateSettingsRequest;
+import org.elasticsearch.cluster.ClusterState;
 import org.elasticsearch.common.settings.ClusterSettings;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.settings.SettingsUpdater;
@@ -94,6 +95,11 @@ public TransformState transform(Object input, TransformState prevState) {
         return new TransformState(state, currentKeys);
     }
 
+    @Override
+    public ClusterState remove(TransformState prevState) throws Exception {
+        return transform(Map.of(), prevState).state();
+    }
+
     @Override
     public Map<String, Object> fromXContent(XContentParser parser) throws IOException {
         return parser.map();

server/src/test/java/org/elasticsearch/reservedstate/ReservedClusterStateHandlerTests.java

@@ -11,6 +11,7 @@
 
 import org.elasticsearch.action.ActionRequestValidationException;
 import org.elasticsearch.action.support.master.MasterNodeRequest;
+import org.elasticsearch.cluster.ClusterState;
 import org.elasticsearch.indices.settings.InternalOrPrivateSettingsPlugin;
 import org.elasticsearch.test.ESTestCase;
 import org.elasticsearch.xcontent.XContentParser;
@@ -32,6 +33,11 @@ public TransformState transform(Object source, TransformState prevState) throws
                 return prevState;
             }
 
+            @Override
+            public ClusterState remove(TransformState prevState) throws Exception {
+                return prevState.state();
+            }
+
             @Override
             public ValidRequest fromXContent(XContentParser parser) throws IOException {
                 return new ValidRequest();

server/src/test/java/org/elasticsearch/reservedstate/service/ReservedClusterStateServiceTests.java

@@ -129,6 +129,11 @@ public TransformState transform(Object source, TransformState prevState) throws
             return new TransformState(newState, prevState.keys());
         }
 
+        @Override
+        public ClusterState remove(TransformState prevState) throws Exception {
+            return transform(null, prevState).state();
+        }
+
         @Override
         public Map<String, Object> fromXContent(XContentParser parser) throws IOException {
             return parser.map();

x-pack/plugin/autoscaling/src/main/java/org/elasticsearch/xpack/autoscaling/action/ReservedAutoscalingPolicyAction.java

@@ -82,6 +82,11 @@ public TransformState transform(Object source, TransformState prevState) throws
 
     }
 
+    @Override
+    public ClusterState remove(TransformState prevState) throws Exception {
+        return transform(List.of(), prevState).state();
+    }
+
     @Override
     public List<PutAutoscalingPolicyAction.Request> fromXContent(XContentParser parser) throws IOException {
         List<PutAutoscalingPolicyAction.Request> result = new ArrayList<>();

x-pack/plugin/ilm/src/main/java/org/elasticsearch/xpack/ilm/action/ReservedLifecycleAction.java

@@ -107,6 +107,11 @@ public TransformState transform(Object source, TransformState prevState) throws
         return new TransformState(state, entities);
     }
 
+    @Override
+    public ClusterState remove(TransformState prevState) throws Exception {
+        return transform(List.of(), prevState).state();
+    }
+
     @Override
     public List<LifecyclePolicy> fromXContent(XContentParser parser) throws IOException {
         List<LifecyclePolicy> result = new ArrayList<>();

x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/action/rolemapping/ReservedRoleMappingAction.java

@@ -57,6 +57,11 @@ public TransformState transform(Object source, TransformState prevState) throws
         }
     }
 
+    @Override
+    public ClusterState remove(TransformState prevState) throws Exception {
+        return transform(List.of(), prevState).state();
+    }
+
     @Override
     public List<PutRoleMappingRequest> fromXContent(XContentParser parser) throws IOException {
         List<PutRoleMappingRequest> result = new ArrayList<>();