Update TransportNodesCapabilitiesAction for V9

docs/changelog/122613.yaml

@@ -0,0 +1,5 @@
+pr: 122613
+summary: Update `TransportNodesCapabilitiesAction` for V9
+area: Infra/REST API
+type: enhancement
+issues: []

libs/core/src/main/java/org/elasticsearch/core/RestApiVersion.java

@@ -62,15 +62,11 @@ public static Predicate<RestApiVersion> onOrAfter(RestApiVersion restApiVersion)
         };
     }
 
-    public static RestApiVersion forMajor(int major) {
-        switch (major) {
-            case 7 -> {
-                return V_7;
-            }
-            case 8 -> {
-                return V_8;
-            }
-            default -> throw new IllegalArgumentException("Unknown REST API version " + major);
-        }
+    public static RestApiVersion forMajorIfKnown(int major) {
+        return switch (major) {
+            case 7 -> V_7;
+            case 8 -> V_8;
+            default -> null;
+        };
     }
 }

server/src/internalClusterTest/java/org/elasticsearch/nodescapabilities/SimpleNodesCapabilitiesIT.java

@@ -12,6 +12,7 @@
 import org.elasticsearch.action.admin.cluster.health.ClusterHealthResponse;
 import org.elasticsearch.action.admin.cluster.node.capabilities.NodesCapabilitiesRequest;
 import org.elasticsearch.action.admin.cluster.node.capabilities.NodesCapabilitiesResponse;
+import org.elasticsearch.core.RestApiVersion;
 import org.elasticsearch.test.ESIntegTestCase;
 
 import java.io.IOException;
@@ -43,6 +44,13 @@ public void testNodesCapabilities() throws IOException {
         assertThat(response.getNodes(), hasSize(2));
         assertThat(response.isSupported(), isPresentWith(true));
 
+        // check we support REST API version parameters of the capabilities API
+        response = clusterAdmin().nodesCapabilities(
+            new NodesCapabilitiesRequest().path("_capabilities").parameters("method", "path").restApiVersion(RestApiVersion.current())
+        ).actionGet();
+        assertThat(response.getNodes(), hasSize(2));
+        assertThat(response.isSupported(), isPresentWith(true));
+
         // check we don't support some other parameters of the capabilities API
         response = clusterAdmin().nodesCapabilities(new NodesCapabilitiesRequest().path("_capabilities").parameters("method", "invalid"))
             .actionGet();

server/src/main/java/org/elasticsearch/action/admin/cluster/node/capabilities/TransportNodesCapabilitiesAction.java

@@ -115,17 +115,19 @@ protected NodeCapability nodeOperation(NodeCapabilitiesRequest request, Task tas
             request.path,
             request.parameters,
             request.capabilities,
-            request.restApiVersion
+            request.restApiVersionMajor
         );
         return new NodeCapability(supported, transportService.getLocalNode());
     }
 
     public static class NodeCapabilitiesRequest extends TransportRequest {
+        private static final int IMPLICIT_REST_API_VERSION = 0;
+
         private final RestRequest.Method method;
         private final String path;
         private final Set<String> parameters;
         private final Set<String> capabilities;
-        private final RestApiVersion restApiVersion;
+        private final Byte restApiVersionMajor;
 
         public NodeCapabilitiesRequest(StreamInput in) throws IOException {
             super(in);
@@ -134,7 +136,9 @@ public NodeCapabilitiesRequest(StreamInput in) throws IOException {
             path = in.readString();
             parameters = in.readCollectionAsImmutableSet(StreamInput::readString);
             capabilities = in.readCollectionAsImmutableSet(StreamInput::readString);
-            restApiVersion = RestApiVersion.forMajor(in.readVInt());
+            byte versionFromMessage = (byte) in.readVInt();
+            // V9 can send IMPLICIT_REST_API_VERSION
+            restApiVersionMajor = (versionFromMessage != IMPLICIT_REST_API_VERSION) ? versionFromMessage : null;
         }
 
         public NodeCapabilitiesRequest(
@@ -148,7 +152,9 @@ public NodeCapabilitiesRequest(
             this.path = path;
             this.parameters = Set.copyOf(parameters);
             this.capabilities = Set.copyOf(capabilities);
-            this.restApiVersion = restApiVersion;
+            assert restApiVersion != null;
+            // restApiVersionMajor can be null only if it is received as part of transport message from v9 node
+            this.restApiVersionMajor = restApiVersion.major;
         }
 
         @Override
@@ -159,7 +165,7 @@ public void writeTo(StreamOutput out) throws IOException {
             out.writeString(path);
             out.writeCollection(parameters, StreamOutput::writeString);
             out.writeCollection(capabilities, StreamOutput::writeString);
-            out.writeVInt(restApiVersion.major);
+            out.writeVInt(restApiVersionMajor);
         }
     }
 }

server/src/main/java/org/elasticsearch/rest/RestController.java

@@ -385,8 +385,14 @@ public boolean checkSupported(
         String path,
         Set<String> parameters,
         Set<String> capabilities,
-        RestApiVersion restApiVersion
+        Byte restApiVersionMajor
     ) {
+        RestApiVersion restApiVersion = getRestApiVersionIfKnown(restApiVersionMajor);
+        // if explicitly requested RestApiVersion is not known by this node, it should respond that it doesn't support the capability
+        if (restApiVersion == null) {
+            return false;
+        }
+
         Iterator<MethodHandlers> allHandlers = getAllHandlers(null, path);
         while (allHandlers.hasNext()) {
             RestHandler handler;
@@ -408,6 +414,16 @@ public boolean checkSupported(
         return false;
     }
 
+    private static RestApiVersion getRestApiVersionIfKnown(Byte restApiVersionMajor) {
+        RestApiVersion restApiVersion;
+        if (restApiVersionMajor == null) {
+            restApiVersion = RestApiVersion.current();
+        } else {
+            restApiVersion = RestApiVersion.forMajorIfKnown(restApiVersionMajor);
+        }
+        return restApiVersion;
+    }
+
     @Override
     public Map<String, HttpRouteStats> getStats() {
         final Iterator<MethodHandlers> methodHandlersIterator = handlers.allNodeValues();