Create health_stats API for query insights

src/main/java/org/opensearch/plugin/insights/QueryInsightsPlugin.java

@@ -31,8 +31,11 @@
 import org.opensearch.plugin.insights.core.listener.QueryInsightsListener;
 import org.opensearch.plugin.insights.core.metrics.OperationalMetricsCounter;
 import org.opensearch.plugin.insights.core.service.QueryInsightsService;
+import org.opensearch.plugin.insights.rules.action.health_stats.HealthStatsAction;
 import org.opensearch.plugin.insights.rules.action.top_queries.TopQueriesAction;
+import org.opensearch.plugin.insights.rules.resthandler.health_stats.RestHealthStatsAction;
 import org.opensearch.plugin.insights.rules.resthandler.top_queries.RestTopQueriesAction;
+import org.opensearch.plugin.insights.rules.transport.health_stats.TransportHealthStatsAction;
 import org.opensearch.plugin.insights.rules.transport.top_queries.TransportTopQueriesAction;
 import org.opensearch.plugin.insights.settings.QueryCategorizationSettings;
 import org.opensearch.plugin.insights.settings.QueryInsightsSettings;
@@ -110,12 +113,15 @@ public List<RestHandler> getRestHandlers(
         final IndexNameExpressionResolver indexNameExpressionResolver,
         final Supplier<DiscoveryNodes> nodesInCluster
     ) {
-        return List.of(new RestTopQueriesAction());
+        return List.of(new RestTopQueriesAction(), new RestHealthStatsAction());
     }
 
     @Override
     public List<ActionHandler<? extends ActionRequest, ? extends ActionResponse>> getActions() {
-        return List.of(new ActionPlugin.ActionHandler<>(TopQueriesAction.INSTANCE, TransportTopQueriesAction.class));
+        return List.of(
+            new ActionPlugin.ActionHandler<>(TopQueriesAction.INSTANCE, TransportTopQueriesAction.class),
+            new ActionPlugin.ActionHandler<>(HealthStatsAction.INSTANCE, TransportHealthStatsAction.class)
+        );
     }
 
     @Override

src/main/java/org/opensearch/plugin/insights/rules/action/health_stats/HealthStatsAction.java

@@ -0,0 +1,30 @@
+/*
+ * 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.plugin.insights.rules.action.health_stats;
+
+import org.opensearch.action.ActionType;
+
+/**
+ * Transport action for cluster/node level query insights plugin health stats.
+ */
+public class HealthStatsAction extends ActionType<HealthStatsResponse> {
+
+    /**
+     * The HealthStatsAction Instance.
+     */
+    public static final HealthStatsAction INSTANCE = new HealthStatsAction();
+    /**
+     * The name of this Action
+     */
+    public static final String NAME = "cluster:admin/opensearch/insights/health_stats";
+
+    private HealthStatsAction() {
+        super(NAME, HealthStatsResponse::new);
+    }
+}

src/main/java/org/opensearch/plugin/insights/rules/action/health_stats/HealthStatsNodeResponse.java

@@ -0,0 +1,69 @@
+/*
+ * 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.plugin.insights.rules.action.health_stats;
+
+import java.io.IOException;
+import org.opensearch.action.support.nodes.BaseNodeResponse;
+import org.opensearch.cluster.node.DiscoveryNode;
+import org.opensearch.core.common.io.stream.StreamInput;
+import org.opensearch.core.common.io.stream.StreamOutput;
+import org.opensearch.core.xcontent.ToXContentObject;
+import org.opensearch.core.xcontent.XContentBuilder;
+import org.opensearch.plugin.insights.rules.model.healthStats.QueryInsightsHealthStats;
+
+/**
+ * Holds the health stats retrieved from a node
+ */
+public class HealthStatsNodeResponse extends BaseNodeResponse implements ToXContentObject {
+    /** The health stats retrieved from one node */
+    private final QueryInsightsHealthStats healthStats;
+
+    /**
+     * Create the HealthStatsNodeResponse Object from StreamInput
+     * @param in A {@link StreamInput} object.
+     * @throws IOException IOException
+     */
+    public HealthStatsNodeResponse(final StreamInput in) throws IOException {
+        super(in);
+        healthStats = new QueryInsightsHealthStats(in);
+    }
+
+    /**
+     * Create the HealthStatsNodeResponse Object
+     * @param node A node that is part of the cluster.
+     * @param healthStats A list of HealthStats from nodes.
+     */
+    public HealthStatsNodeResponse(final DiscoveryNode node, final QueryInsightsHealthStats healthStats) {
+        super(node);
+        this.healthStats = healthStats;
+    }
+
+    @Override
+    public XContentBuilder toXContent(final XContentBuilder builder, final Params params) throws IOException {
+        builder.startObject(this.getNode().getId());
+        healthStats.toXContent(builder, params);
+        return builder.endObject();
+    }
+
+    @Override
+    public void writeTo(final StreamOutput out) throws IOException {
+        super.writeTo(out);
+        healthStats.writeTo(out);
+
+    }
+
+    /**
+     * Get health stats
+     *
+     * @return the health stats records in this node response
+     */
+    public QueryInsightsHealthStats getHealthStats() {
+        return healthStats;
+    }
+}

src/main/java/org/opensearch/plugin/insights/rules/action/health_stats/HealthStatsRequest.java

@@ -0,0 +1,44 @@
+/*
+ * 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.plugin.insights.rules.action.health_stats;
+
+import java.io.IOException;
+import org.opensearch.action.support.nodes.BaseNodesRequest;
+import org.opensearch.core.common.io.stream.StreamInput;
+import org.opensearch.core.common.io.stream.StreamOutput;
+
+/**
+ * A request to get cluster/node level health stats information.
+ */
+public class HealthStatsRequest extends BaseNodesRequest<HealthStatsRequest> {
+    /**
+     * Constructor for HealthStatsRequest
+     *
+     * @param in A {@link StreamInput} object.
+     * @throws IOException if the stream cannot be deserialized.
+     */
+    public HealthStatsRequest(final StreamInput in) throws IOException {
+        super(in);
+    }
+
+    /**
+     * Get health stats from nodes based on the nodes ids specified.
+     * If none are passed, cluster level health stats will be returned.
+     *
+     * @param nodesIds the nodeIds specified in the request
+     */
+    public HealthStatsRequest(final String... nodesIds) {
+        super(nodesIds);
+    }
+
+    @Override
+    public void writeTo(final StreamOutput out) throws IOException {
+        super.writeTo(out);
+    }
+}

src/main/java/org/opensearch/plugin/insights/rules/action/health_stats/HealthStatsResponse.java

@@ -0,0 +1,83 @@
+/*
+ * 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.plugin.insights.rules.action.health_stats;
+
+import java.io.IOException;
+import java.util.List;
+import org.opensearch.action.FailedNodeException;
+import org.opensearch.action.support.nodes.BaseNodesResponse;
+import org.opensearch.cluster.ClusterName;
+import org.opensearch.common.xcontent.XContentFactory;
+import org.opensearch.core.common.io.stream.StreamInput;
+import org.opensearch.core.common.io.stream.StreamOutput;
+import org.opensearch.core.xcontent.ToXContentFragment;
+import org.opensearch.core.xcontent.XContentBuilder;
+
+/**
+ * Transport response for cluster/node level health stats
+ */
+public class HealthStatsResponse extends BaseNodesResponse<HealthStatsNodeResponse> implements ToXContentFragment {
+    /**
+     * Constructor for HealthStatsNodeResponseResponse.
+     *
+     * @param in A {@link StreamInput} object.
+     * @throws IOException if the stream cannot be deserialized.
+     */
+    public HealthStatsResponse(final StreamInput in) throws IOException {
+        super(in);
+    }
+
+    /**
+     * Constructor for HealthStatsResponse
+     *
+     * @param clusterName The current cluster name
+     * @param nodes A list that contains health stats from all nodes
+     * @param failures A list that contains FailedNodeException
+     */
+    public HealthStatsResponse(
+        final ClusterName clusterName,
+        final List<HealthStatsNodeResponse> nodes,
+        final List<FailedNodeException> failures
+    ) {
+        super(clusterName, nodes, failures);
+    }
+
+    @Override
+    protected List<HealthStatsNodeResponse> readNodesFrom(final StreamInput in) throws IOException {
+        return in.readList(HealthStatsNodeResponse::new);
+    }
+
+    @Override
+    protected void writeNodesTo(final StreamOutput out, final List<HealthStatsNodeResponse> nodes) throws IOException {
+        out.writeList(nodes);
+    }
+
+    @Override
+    public XContentBuilder toXContent(final XContentBuilder builder, final Params params) throws IOException {
+        final List<HealthStatsNodeResponse> results = getNodes();
+        builder.startObject();
+        for (HealthStatsNodeResponse nodeResponse : results) {
+            nodeResponse.toXContent(builder, params);
+        }
+        return builder.endObject();
+    }
+
+    @Override
+    public String toString() {
+        try {
+            final XContentBuilder builder = XContentFactory.jsonBuilder().prettyPrint();
+            builder.startObject();
+            this.toXContent(builder, EMPTY_PARAMS);
+            builder.endObject();
+            return builder.toString();
+        } catch (IOException e) {
+            return "{ \"error\" : \"" + e.getMessage() + "\"}";
+        }
+    }
+}

src/main/java/org/opensearch/plugin/insights/rules/action/health_stats/package-info.java

@@ -0,0 +1,12 @@
+/*
+ * 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.
+ */
+
+/**
+ * Transport Actions, Requests and Responses for Query Insights Health Stats
+ */
+package org.opensearch.plugin.insights.rules.action.health_stats;

src/main/java/org/opensearch/plugin/insights/rules/resthandler/health_stats/RestHealthStatsAction.java

@@ -0,0 +1,81 @@
+/*
+ * 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.plugin.insights.rules.resthandler.health_stats;
+
+import static org.opensearch.plugin.insights.settings.QueryInsightsSettings.QUERY_INSIGHTS_HEALTH_STATS_URI;
+import static org.opensearch.rest.RestRequest.Method.GET;
+
+import java.util.List;
+import java.util.Set;
+import org.opensearch.client.node.NodeClient;
+import org.opensearch.common.settings.Settings;
+import org.opensearch.core.common.Strings;
+import org.opensearch.core.rest.RestStatus;
+import org.opensearch.core.xcontent.ToXContent;
+import org.opensearch.plugin.insights.rules.action.health_stats.HealthStatsAction;
+import org.opensearch.plugin.insights.rules.action.health_stats.HealthStatsRequest;
+import org.opensearch.plugin.insights.rules.action.health_stats.HealthStatsResponse;
+import org.opensearch.rest.BaseRestHandler;
+import org.opensearch.rest.BytesRestResponse;
+import org.opensearch.rest.RestChannel;
+import org.opensearch.rest.RestRequest;
+import org.opensearch.rest.RestResponse;
+import org.opensearch.rest.action.RestResponseListener;
+
+/**
+ * Rest action to get operational health stats of the query insights plugin
+ */
+public class RestHealthStatsAction extends BaseRestHandler {
+    /**
+     * Constructor for RestHealthStatsAction
+     */
+    public RestHealthStatsAction() {}
+
+    @Override
+    public List<Route> routes() {
+        return List.of(new Route(GET, QUERY_INSIGHTS_HEALTH_STATS_URI));
+    }
+
+    @Override
+    public String getName() {
+        return "query_insights_health_stats_action";
+    }
+
+    @Override
+    public RestChannelConsumer prepareRequest(final RestRequest request, final NodeClient client) {
+        final HealthStatsRequest healthStatsRequest = prepareRequest(request);
+        healthStatsRequest.timeout(request.param("timeout"));
+
+        return channel -> client.execute(HealthStatsAction.INSTANCE, healthStatsRequest, healthStatsResponse(channel));
+    }
+
+    static HealthStatsRequest prepareRequest(final RestRequest request) {
+        final String[] nodesIds = Strings.splitStringByCommaToArray(request.param("nodeId"));
+        return new HealthStatsRequest(nodesIds);
+    }
+
+    @Override
+    protected Set<String> responseParams() {
+        return Settings.FORMAT_PARAMS;
+    }
+
+    @Override
+    public boolean canTripCircuitBreaker() {
+        return false;
+    }
+
+    RestResponseListener<HealthStatsResponse> healthStatsResponse(final RestChannel channel) {
+        return new RestResponseListener<>(channel) {
+            @Override
+            public RestResponse buildResponse(final HealthStatsResponse response) throws Exception {
+                return new BytesRestResponse(RestStatus.OK, response.toXContent(channel.newBuilder(), ToXContent.EMPTY_PARAMS));
+            }
+        };
+    }
+}

src/main/java/org/opensearch/plugin/insights/rules/resthandler/health_stats/package-info.java

@@ -0,0 +1,12 @@
+/*
+ * 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.
+ */
+
+/**
+ * Rest Handlers for Query Insights Health Stats
+ */
+package org.opensearch.plugin.insights.rules.resthandler.health_stats;