Add changes for graceful node decommission

CHANGELOG.md

@@ -20,6 +20,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Add BWC version 2.3.1 ([#4513](https://github.com/opensearch-project/OpenSearch/pull/4513))
 - [Segment Replication] Add snapshot and restore tests for segment replication feature ([#3993](https://github.com/opensearch-project/OpenSearch/pull/3993))
 - Added missing javadocs for `:example-plugins` modules ([#4540](https://github.com/opensearch-project/OpenSearch/pull/4540))
+- Added changes for graceful node decommission ([#4586](https://github.com/opensearch-project/OpenSearch/pull/4586))
 ### Dependencies
 - Bumps `log4j-core` from 2.18.0 to 2.19.0
 

server/src/main/java/org/opensearch/action/admin/cluster/shards/routing/wrr/put/ClusterPutWRRWeightsAction.java

@@ -0,0 +1,27 @@
+/*
+ * 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.action.admin.cluster.shards.routing.wrr.put;
+
+import org.opensearch.action.ActionType;
+
+/**
+ * Action to update weights for weighted round-robin shard routing policy.
+ *
+ * @opensearch.internal
+ */
+public final class ClusterPutWRRWeightsAction extends ActionType<ClusterPutWRRWeightsResponse> {
+
+    public static final ClusterPutWRRWeightsAction INSTANCE = new ClusterPutWRRWeightsAction();
+    public static final String NAME = "cluster:admin/routing/awareness/weights/put";
+
+    private ClusterPutWRRWeightsAction() {
+        super(NAME, ClusterPutWRRWeightsResponse::new);
+    }
+
+}

server/src/main/java/org/opensearch/action/admin/cluster/shards/routing/wrr/put/ClusterPutWRRWeightsRequest.java

@@ -0,0 +1,164 @@
+/*
+ * 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.action.admin.cluster.shards.routing.wrr.put;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.opensearch.OpenSearchGenerationException;
+import org.opensearch.OpenSearchParseException;
+import org.opensearch.action.ActionRequestValidationException;
+import org.opensearch.action.support.clustermanager.ClusterManagerNodeRequest;
+import org.opensearch.cluster.routing.WRRWeights;
+import org.opensearch.common.bytes.BytesReference;
+import org.opensearch.common.io.stream.StreamInput;
+import org.opensearch.common.io.stream.StreamOutput;
+import org.opensearch.common.xcontent.DeprecationHandler;
+import org.opensearch.common.xcontent.NamedXContentRegistry;
+import org.opensearch.common.xcontent.XContentBuilder;
+import org.opensearch.common.xcontent.XContentFactory;
+import org.opensearch.common.xcontent.XContentHelper;
+import org.opensearch.common.xcontent.XContentParser;
+import org.opensearch.common.xcontent.XContentType;
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+
+import static org.opensearch.action.ValidateActions.addValidationError;
+
+/**
+ * Request to update weights for weighted round-robin shard routing policy.
+ *
+ * @opensearch.internal
+ */
+public class ClusterPutWRRWeightsRequest extends ClusterManagerNodeRequest<ClusterPutWRRWeightsRequest> {
+    private static final Logger logger = LogManager.getLogger(ClusterPutWRRWeightsRequest.class);
+
+    private WRRWeights wrrWeight;
+    private String attributeName;
+
+    public WRRWeights wrrWeight() {
+        return wrrWeight;
+    }
+
+    public ClusterPutWRRWeightsRequest wrrWeight(WRRWeights wrrWeight) {
+        this.wrrWeight = wrrWeight;
+        return this;
+    }
+
+    public void attributeName(String attributeName) {
+        this.attributeName = attributeName;
+    }
+
+    public ClusterPutWRRWeightsRequest(StreamInput in) throws IOException {
+        super(in);
+        wrrWeight = new WRRWeights(in);
+    }
+
+    public ClusterPutWRRWeightsRequest() {
+
+    }
+
+    public void setWRRWeight(Map<String, String> source) {
+        try {
+            if (source.isEmpty()) {
+                throw new OpenSearchParseException(("Empty request body"));
+            }
+            XContentBuilder builder = XContentFactory.jsonBuilder();
+            builder.map(source);
+            setWRRWeight(BytesReference.bytes(builder), builder.contentType());
+        } catch (IOException e) {
+            throw new OpenSearchGenerationException("Failed to generate [" + source + "]", e);
+        }
+    }
+
+    public void setWRRWeight(BytesReference source, XContentType contentType) {
+        try (
+            XContentParser parser = XContentHelper.createParser(
+                NamedXContentRegistry.EMPTY,
+                DeprecationHandler.THROW_UNSUPPORTED_OPERATION,
+                source,
+                contentType
+            )
+        ) {
+            String attrValue = null;
+            Map<String, Object> weights = new HashMap<>();
+            Object attrWeight = null;
+            XContentParser.Token token;
+            // move to the first alias
+            parser.nextToken();
+            while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
+                if (token == XContentParser.Token.FIELD_NAME) {
+                    attrValue = parser.currentName();
+                } else if (token == XContentParser.Token.VALUE_STRING) {
+                    attrWeight = parser.text();
+                    weights.put(attrValue, attrWeight);
+                } else {
+                    throw new OpenSearchParseException("failed to parse wrr request attribute [{}], unknown type", attrWeight);
+                }
+            }
+            this.wrrWeight = new WRRWeights(this.attributeName, weights);
+        } catch (IOException e) {
+            logger.error("error while parsing put wrr weights request object", e);
+        }
+    }
+
+    @Override
+    public ActionRequestValidationException validate() {
+        ActionRequestValidationException validationException = null;
+        if (wrrWeight == null) {
+            validationException = addValidationError("WRRWeights object is null", validationException);
+        }
+        if (wrrWeight.attributeName() == null || wrrWeight.attributeName().isEmpty()) {
+            validationException = addValidationError("Attribute name is missing", validationException);
+        }
+        if (wrrWeight.weights() == null || wrrWeight.weights().isEmpty()) {
+            validationException = addValidationError("Weights are missing", validationException);
+        }
+        int countValueWithZeroWeights = 0;
+        int weight;
+        try {
+            for (Object value : wrrWeight.weights().values()) {
+                if (value == null) {
+                    validationException = addValidationError(("Weight is null"), validationException);
+                } else {
+                    weight = Integer.parseInt(value.toString());
+                    countValueWithZeroWeights = (weight == 0) ? countValueWithZeroWeights + 1 : countValueWithZeroWeights;
+                }
+            }
+        } catch (NumberFormatException e) {
+            validationException = addValidationError(("Weight is non-integer"), validationException);
+        }
+        if (countValueWithZeroWeights > 1) {
+            validationException = addValidationError(("More than one value has weight set as 0 "), validationException);
+        }
+
+        return validationException;
+    }
+
+    /**
+     * @param source weights definition from request body
+     * @return this request
+     */
+    public ClusterPutWRRWeightsRequest source(Map<String, String> source) {
+        setWRRWeight(source);
+        return this;
+    }
+
+    @Override
+    public void writeTo(StreamOutput out) throws IOException {
+        super.writeTo(out);
+        wrrWeight.writeTo(out);
+    }
+
+    @Override
+    public String toString() {
+        return "ClusterPutWRRWeightsRequest{" + "wrrWeight= " + wrrWeight.toString() + "}";
+    }
+}

server/src/main/java/org/opensearch/action/admin/cluster/shards/routing/wrr/put/ClusterPutWRRWeightsResponse.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.action.admin.cluster.shards.routing.wrr.put;
+
+import org.opensearch.action.support.master.AcknowledgedResponse;
+import org.opensearch.common.io.stream.StreamInput;
+import org.opensearch.common.xcontent.ToXContentObject;
+
+import java.io.IOException;
+
+/**
+ * Response from updating weights for weighted round-robin search routing policy.
+ *
+ * @opensearch.internal
+ */
+public class ClusterPutWRRWeightsResponse extends AcknowledgedResponse implements ToXContentObject {
+    public ClusterPutWRRWeightsResponse(boolean acknowledged) {
+        super(acknowledged);
+    }
+
+    public ClusterPutWRRWeightsResponse(StreamInput in) throws IOException {
+        super(in);
+    }
+}

server/src/main/java/org/opensearch/action/admin/cluster/shards/routing/wrr/put/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.
+ */
+
+/**
+ * WRR Weights request objects.
+ */
+package org.opensearch.action.admin.cluster.shards.routing.wrr.put;