Fix interchanged formats of total_indexing_buffer_in_bytes and total_indexing_buffer

CHANGELOG-3.0.md

@@ -50,6 +50,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Fix 'org.apache.hc.core5.http.ParseException: Invalid protocol version' under JDK 16+ ([#4827](https://github.com/opensearch-project/OpenSearch/pull/4827))
 - Fix compression support for h2c protocol ([#4944](https://github.com/opensearch-project/OpenSearch/pull/4944))
 - Don't over-allocate in HeapBufferedAsyncEntityConsumer in order to consume the response ([#9993](https://github.com/opensearch-project/OpenSearch/pull/9993))
+- Fix swapped field formats in nodes API where `total_indexing_buffer_in_bytes` and `total_indexing_buffer` values were reversed ([#17070](https://github.com/opensearch-project/OpenSearch/pull/17070))
+
 
 ### Security
 

rest-api-spec/src/main/resources/rest-api-spec/test/nodes.info/50_nodes_total_indexing_buffer_format.yml

@@ -0,0 +1,21 @@
+---
+"Test total indexing buffer fields should have correct formats":
+  - skip:
+      version: " - 2.99.99"
+      reason: "this change is added in 3.0.0"
+      features: [arbitrary_key]
+
+  - do:
+      nodes.info: {}
+  - set:
+      nodes._arbitrary_key_: node_id
+
+  - do:
+      nodes.info:
+        human: true
+        filter_path: "nodes.*.total_indexing_buffer*"
+
+  - gte: { nodes.$node_id.total_indexing_buffer_in_bytes: 0 }
+
+  - match:
+      nodes.$node_id.total_indexing_buffer: /^\d+(\.\d+)?(b|kb|mb|gb|tb|pb)$/

server/src/main/java/org/opensearch/action/admin/cluster/node/info/NodesInfoResponse.java

@@ -98,7 +98,7 @@
             builder.field("build_type", nodeInfo.getBuild().type().displayName());
             builder.field("build_hash", nodeInfo.getBuild().hash());
             if (nodeInfo.getTotalIndexingBuffer() != null) {
-                builder.humanReadableField("total_indexing_buffer", "total_indexing_buffer_in_bytes", nodeInfo.getTotalIndexingBuffer());
+                builder.humanReadableField("total_indexing_buffer_in_bytes", "total_indexing_buffer", nodeInfo.getTotalIndexingBuffer());
             }
 
             builder.startArray("roles");