Add a capabilities API to check node and cluster capabilities (elasti…

…c#106820)

This adds a /_capabilities rest endpoint for checking the capabilities of a cluster - what endpoints, parameters, and endpoint capabilities the cluster supports

docs/changelog/106820.yaml

@@ -0,0 +1,5 @@
+pr: 106820
+summary: Add a capabilities API to check node and cluster capabilities
+area: Infra/REST API
+type: feature
+issues: []

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

@@ -61,4 +61,15 @@ 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);
+        }
+    }
 }

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

@@ -0,0 +1,55 @@
+/*
+ * 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 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 or the Server
+ * Side Public License, v 1.
+ */
+
+package org.elasticsearch.nodescapabilities;
+
+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.test.ESIntegTestCase;
+
+import java.io.IOException;
+
+import static org.hamcrest.Matchers.hasSize;
+import static org.hamcrest.Matchers.is;
+
+@ESIntegTestCase.ClusterScope(scope = ESIntegTestCase.Scope.TEST, numDataNodes = 0)
+public class SimpleNodesCapabilitiesIT extends ESIntegTestCase {
+
+    public void testNodesCapabilities() throws IOException {
+        internalCluster().startNodes(2);
+
+        ClusterHealthResponse clusterHealth = clusterAdmin().prepareHealth().setWaitForGreenStatus().setWaitForNodes("2").get();
+        logger.info("--> done cluster_health, status {}", clusterHealth.getStatus());
+
+        // check we support the capabilities API itself. Which we do.
+        NodesCapabilitiesResponse response = clusterAdmin().nodesCapabilities(new NodesCapabilitiesRequest().path("_capabilities"))
+            .actionGet();
+        assertThat(response.getNodes(), hasSize(2));
+        assertThat(response.isSupported(), is(true));
+
+        // check we support some parameters of the capabilities API
+        response = clusterAdmin().nodesCapabilities(new NodesCapabilitiesRequest().path("_capabilities").parameters("method", "path"))
+            .actionGet();
+        assertThat(response.getNodes(), hasSize(2));
+        assertThat(response.isSupported(), is(true));
+
+        // check we don't support some other parameters of the capabilities API
+        response = clusterAdmin().nodesCapabilities(new NodesCapabilitiesRequest().path("_capabilities").parameters("method", "invalid"))
+            .actionGet();
+        assertThat(response.getNodes(), hasSize(2));
+        assertThat(response.isSupported(), is(false));
+
+        // check we don't support a random invalid api
+        // TODO this is not working yet - see https://github.com/elastic/elasticsearch/issues/107425
+        /*response = clusterAdmin().nodesCapabilities(new NodesCapabilitiesRequest().path("_invalid"))
+            .actionGet();
+        assertThat(response.getNodes(), hasSize(2));
+        assertThat(response.isSupported(), is(false));*/
+    }
+}

server/src/main/java/module-info.java

@@ -65,6 +65,7 @@
     exports org.elasticsearch.action.admin.cluster.desirednodes;
     exports org.elasticsearch.action.admin.cluster.health;
     exports org.elasticsearch.action.admin.cluster.migration;
+    exports org.elasticsearch.action.admin.cluster.node.capabilities;
     exports org.elasticsearch.action.admin.cluster.node.hotthreads;
     exports org.elasticsearch.action.admin.cluster.node.info;
     exports org.elasticsearch.action.admin.cluster.node.reload;

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

@@ -29,6 +29,7 @@
 import org.elasticsearch.action.admin.cluster.migration.PostFeatureUpgradeAction;
 import org.elasticsearch.action.admin.cluster.migration.TransportGetFeatureUpgradeStatusAction;
 import org.elasticsearch.action.admin.cluster.migration.TransportPostFeatureUpgradeAction;
+import org.elasticsearch.action.admin.cluster.node.capabilities.TransportNodesCapabilitiesAction;
 import org.elasticsearch.action.admin.cluster.node.hotthreads.TransportNodesHotThreadsAction;
 import org.elasticsearch.action.admin.cluster.node.info.TransportNodesInfoAction;
 import org.elasticsearch.action.admin.cluster.node.reload.TransportNodesReloadSecureSettingsAction;
@@ -284,6 +285,7 @@
 import org.elasticsearch.rest.action.admin.cluster.RestGetStoredScriptAction;
 import org.elasticsearch.rest.action.admin.cluster.RestGetTaskAction;
 import org.elasticsearch.rest.action.admin.cluster.RestListTasksAction;
+import org.elasticsearch.rest.action.admin.cluster.RestNodesCapabilitiesAction;
 import org.elasticsearch.rest.action.admin.cluster.RestNodesHotThreadsAction;
 import org.elasticsearch.rest.action.admin.cluster.RestNodesInfoAction;
 import org.elasticsearch.rest.action.admin.cluster.RestNodesStatsAction;
@@ -616,6 +618,7 @@ public <Request extends ActionRequest, Response extends ActionResponse> void reg
 
         actions.register(TransportNodesInfoAction.TYPE, TransportNodesInfoAction.class);
         actions.register(TransportRemoteInfoAction.TYPE, TransportRemoteInfoAction.class);
+        actions.register(TransportNodesCapabilitiesAction.TYPE, TransportNodesCapabilitiesAction.class);
         actions.register(RemoteClusterNodesAction.TYPE, RemoteClusterNodesAction.TransportAction.class);
         actions.register(TransportNodesStatsAction.TYPE, TransportNodesStatsAction.class);
         actions.register(TransportNodesUsageAction.TYPE, TransportNodesUsageAction.class);
@@ -833,6 +836,7 @@ public void initRestHandlers(Supplier<DiscoveryNodes> nodesInCluster, Predicate<
         registerHandler.accept(new RestClearVotingConfigExclusionsAction());
         registerHandler.accept(new RestNodesInfoAction(settingsFilter));
         registerHandler.accept(new RestRemoteClusterInfoAction());
+        registerHandler.accept(new RestNodesCapabilitiesAction());
         registerHandler.accept(new RestNodesStatsAction());
         registerHandler.accept(new RestNodesUsageAction());
         registerHandler.accept(new RestNodesHotThreadsAction());
@@ -1029,6 +1033,7 @@ public void initRestHandlers(Supplier<DiscoveryNodes> nodesInCluster, Predicate<
 
     @Override
     protected void configure() {
+        bind(RestController.class).toInstance(restController);
         bind(ActionFilters.class).toInstance(actionFilters);
         bind(DestructiveOperations.class).toInstance(destructiveOperations);
         bind(new TypeLiteral<RequestValidators<PutMappingRequest>>() {

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

@@ -0,0 +1,43 @@
+/*
+ * 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 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 or the Server
+ * Side Public License, v 1.
+ */
+
+package org.elasticsearch.action.admin.cluster.node.capabilities;
+
+import org.elasticsearch.action.support.nodes.BaseNodeResponse;
+import org.elasticsearch.cluster.node.DiscoveryNode;
+import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.common.io.stream.StreamOutput;
+
+import java.io.IOException;
+
+public class NodeCapability extends BaseNodeResponse {
+
+    private final boolean supported;
+
+    public NodeCapability(StreamInput in) throws IOException {
+        super(in);
+
+        supported = in.readBoolean();
+    }
+
+    public NodeCapability(boolean supported, DiscoveryNode node) {
+        super(node);
+        this.supported = supported;
+    }
+
+    public boolean isSupported() {
+        return supported;
+    }
+
+    @Override
+    public void writeTo(StreamOutput out) throws IOException {
+        super.writeTo(out);
+
+        out.writeBoolean(supported);
+    }
+}

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

@@ -0,0 +1,75 @@
+/*
+ * 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 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 or the Server
+ * Side Public License, v 1.
+ */
+
+package org.elasticsearch.action.admin.cluster.node.capabilities;
+
+import org.elasticsearch.action.support.nodes.BaseNodesRequest;
+import org.elasticsearch.common.Strings;
+import org.elasticsearch.core.RestApiVersion;
+import org.elasticsearch.rest.RestRequest;
+
+import java.util.Set;
+
+public class NodesCapabilitiesRequest extends BaseNodesRequest<NodesCapabilitiesRequest> {
+
+    private RestRequest.Method method = RestRequest.Method.GET;
+    private String path = "/";
+    private Set<String> parameters = Set.of();
+    private Set<String> capabilities = Set.of();
+    private RestApiVersion restApiVersion = RestApiVersion.current();
+
+    public NodesCapabilitiesRequest() {
+        // always send to all nodes
+        super(Strings.EMPTY_ARRAY);
+    }
+
+    public NodesCapabilitiesRequest path(String path) {
+        this.path = path;
+        return this;
+    }
+
+    public String path() {
+        return path;
+    }
+
+    public NodesCapabilitiesRequest method(RestRequest.Method method) {
+        this.method = method;
+        return this;
+    }
+
+    public RestRequest.Method method() {
+        return method;
+    }
+
+    public NodesCapabilitiesRequest parameters(String... parameters) {
+        this.parameters = Set.of(parameters);
+        return this;
+    }
+
+    public Set<String> parameters() {
+        return parameters;
+    }
+
+    public NodesCapabilitiesRequest capabilities(String... capabilities) {
+        this.capabilities = Set.of(capabilities);
+        return this;
+    }
+
+    public Set<String> capabilities() {
+        return capabilities;
+    }
+
+    public NodesCapabilitiesRequest restApiVersion(RestApiVersion restApiVersion) {
+        this.restApiVersion = restApiVersion;
+        return this;
+    }
+
+    public RestApiVersion restApiVersion() {
+        return restApiVersion;
+    }
+}

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

@@ -0,0 +1,46 @@
+/*
+ * 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 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 or the Server
+ * Side Public License, v 1.
+ */
+
+package org.elasticsearch.action.admin.cluster.node.capabilities;
+
+import org.elasticsearch.action.FailedNodeException;
+import org.elasticsearch.action.support.TransportAction;
+import org.elasticsearch.action.support.nodes.BaseNodesResponse;
+import org.elasticsearch.cluster.ClusterName;
+import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.common.io.stream.StreamOutput;
+import org.elasticsearch.xcontent.ToXContentFragment;
+import org.elasticsearch.xcontent.XContentBuilder;
+
+import java.io.IOException;
+import java.util.List;
+
+public class NodesCapabilitiesResponse extends BaseNodesResponse<NodeCapability> implements ToXContentFragment {
+    protected NodesCapabilitiesResponse(ClusterName clusterName, List<NodeCapability> nodes, List<FailedNodeException> failures) {
+        super(clusterName, nodes, failures);
+    }
+
+    @Override
+    protected List<NodeCapability> readNodesFrom(StreamInput in) throws IOException {
+        return TransportAction.localOnly();
+    }
+
+    @Override
+    protected void writeNodesTo(StreamOutput out, List<NodeCapability> nodes) throws IOException {
+        TransportAction.localOnly();
+    }
+
+    public boolean isSupported() {
+        return getNodes().isEmpty() == false && getNodes().stream().allMatch(NodeCapability::isSupported);
+    }
+
+    @Override
+    public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
+        return builder.field("supported", isSupported());
+    }
+}