diff --git a/CHANGELOG.md b/CHANGELOG.md
index 31e3f5a1541f..3e276e756d15 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,7 +1,9 @@
 # CHANGELOG
+
 Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
 ## [Unreleased]
+
 ### 💥 Breaking Changes
 
 ### Deprecations
@@ -10,11 +12,13 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
 ### 📈 Features/Enhancements
 
+- [MD] Support legacy client for data source ([#2204](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2204))
+
 ### 🐛 Bug Fixes
 
 ### 🚞 Infrastructure
 
-* Add CHANGELOG.md and related workflows ([#2414](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2414))
+- Add CHANGELOG.md and related workflows ([#2414](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2414))
 
 ### 📝 Documentation
 
@@ -25,47 +29,47 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 ### 🔩 Tests
 
 ## [2.x]
+
 ### 💥 Breaking Changes
 
 ### Deprecations
 
 ### 🛡 Security
 
-* Use a forced CSP-compliant interpreter with Vega visualizations ([#2352](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2352))
-* Bump moment-timezone from 0.5.34 to 0.5.37 ([#2361](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2361))
-* [CVE-2022-33987] Upgrade geckodriver to 3.0.2 ([#2166](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2166)) 
+- Use a forced CSP-compliant interpreter with Vega visualizations ([#2352](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2352))
+- Bump moment-timezone from 0.5.34 to 0.5.37 ([#2361](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2361))
+- [CVE-2022-33987] Upgrade geckodriver to 3.0.2 ([#2166](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2166))
 
 ### 📈 Features/Enhancements
 
-* Add updated_at column to objects' tables ([#1218](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/1218)) 
+- Add updated_at column to objects' tables ([#1218](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/1218))
 
 ### 🐛 Bug Fixes
 
-* [Viz Builder] Fixes time series for new chart types ([#2309](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2309))
-* [Viz Builder] Add index pattern info when loading embeddable ([#2363](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2363))
-* Fixes management app breadcrumb error ([#2344](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2344))
+- [Viz Builder] Fixes time series for new chart types ([#2309](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2309))
+- [Viz Builder] Add index pattern info when loading embeddable ([#2363](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2363))
+- Fixes management app breadcrumb error ([#2344](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2344))
 
 ### 🚞 Infrastructure
 
-* Add path ignore for markdown files for CI ([#2312](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2312))
-* Updating WS scans to ignore BWC artifacts in `cypress` ([#2408](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2408))
-
+- Add path ignore for markdown files for CI ([#2312](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2312))
+- Updating WS scans to ignore BWC artifacts in `cypress` ([#2408](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2408))
 
 ### 📝 Documentation
 
-* README.md for saving index pattern relationship ([#2276](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2276))
-* Remove extra typo from README. ([#2403](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2403))
+- README.md for saving index pattern relationship ([#2276](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2276))
+- Remove extra typo from README. ([#2403](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2403))
 
 ### 🛠 Maintenance
 
-* Increment from 2.3 to 2.4. ([#2295](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2295))
-* Adding @zengyan-amazon as maintainer.
+- Increment from 2.3 to 2.4. ([#2295](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2295))
+- Adding @zengyan-amazon as maintainer.
 
 ### 🪛 Refactoring
 
 ### 🔩 Tests
 
-* Update caniuse to fix failed integration tests ([#2322](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2322))
+- Update caniuse to fix failed integration tests ([#2322](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2322))
 
-[Unreleased]: https://github.com/opensearch-project/OpenSearch-Dashboards/compare/2.3.0...HEAD
+[unreleased]: https://github.com/opensearch-project/OpenSearch-Dashboards/compare/2.3.0...HEAD
 [2.x]: https://github.com/opensearch-project/OpenSearch-Dashboards/compare/2.3.0...2.x
diff --git a/src/core/server/opensearch/legacy/cluster_client.ts b/src/core/server/opensearch/legacy/cluster_client.ts
index ab8bd4f8ceb0..bb8884fd3952 100644
--- a/src/core/server/opensearch/legacy/cluster_client.ts
+++ b/src/core/server/opensearch/legacy/cluster_client.ts
@@ -65,7 +65,7 @@ const noop = () => undefined;
  * OpenSearch JS client.
  * @param options Options that affect the way we call the API and process the result.
  */
-export const callAPI = async (
+const callAPI = async (
   client: Client,
   endpoint: string,
   clientParams: Record<string, any> = {},
diff --git a/src/plugins/data_source/server/legacy/configure_legacy_client.ts b/src/plugins/data_source/server/legacy/configure_legacy_client.ts
index 84514c85b048..63ca6c714744 100644
--- a/src/plugins/data_source/server/legacy/configure_legacy_client.ts
+++ b/src/plugins/data_source/server/legacy/configure_legacy_client.ts
@@ -4,9 +4,15 @@
  */
 
 import { Client } from 'elasticsearch';
-// eslint-disable-next-line @osd/eslint/no-restricted-paths
-import { callAPI } from '../../../../../src/core/server/opensearch/legacy/cluster_client';
-import { Headers, LegacyAPICaller, Logger, SavedObject } from '../../../../../src/core/server';
+import { get } from 'lodash';
+import {
+  Headers,
+  LegacyAPICaller,
+  LegacyCallAPIOptions,
+  LegacyOpenSearchErrorHelpers,
+  Logger,
+  SavedObject,
+} from '../../../../../src/core/server';
 import {
   AuthType,
   DataSourceAttributes,
@@ -87,6 +93,48 @@ const getRootClient = (
   }
 };
 
+/**
+ * Calls the OpenSearch API endpoint with the specified parameters.
+ * @param client Raw OpenSearch JS client instance to use.
+ * @param endpoint Name of the API endpoint to call.
+ * @param clientParams Parameters that will be directly passed to the
+ * OpenSearch JS client.
+ * @param options Options that affect the way we call the API and process the result.
+ * make wrap401Errors default to false, because we don't want browser login pop-up
+ */
+const callAPI = async (
+  client: Client,
+  endpoint: string,
+  clientParams: Record<string, any> = {},
+  options: LegacyCallAPIOptions = { wrap401Errors: false }
+) => {
+  const clientPath = endpoint.split('.');
+  const api: any = get(client, clientPath);
+  if (!api) {
+    throw new Error(`called with an invalid endpoint: ${endpoint}`);
+  }
+
+  const apiContext = clientPath.length === 1 ? client : get(client, clientPath.slice(0, -1));
+  try {
+    return await new Promise((resolve, reject) => {
+      const request = api.call(apiContext, clientParams);
+      if (options.signal) {
+        options.signal.addEventListener('abort', () => {
+          request.abort();
+          reject(new Error('Request was aborted'));
+        });
+      }
+      return request.then(resolve, reject);
+    });
+  } catch (err) {
+    if (!options.wrap401Errors || err.statusCode !== 401) {
+      throw err;
+    }
+
+    throw LegacyOpenSearchErrorHelpers.decorateNotAuthorizedError(err);
+  }
+};
+
 /**
  * Wrapper to expose API that allow calling the OpenSearch API endpoint with the specified
  * parameters, using legacy client.
diff --git a/src/plugins/data_source/server/lib/error.ts b/src/plugins/data_source/server/lib/error.ts
index e921a8d8043f..71830a440c9f 100644
--- a/src/plugins/data_source/server/lib/error.ts
+++ b/src/plugins/data_source/server/lib/error.ts
@@ -14,8 +14,8 @@ export class DataSourceConfigError extends OsdError {
       ? error.output.payload.message
       : error.message;
     super(messagePrefix + messageContent);
-    // Cast all 5xx error returned by saveObjectClient to 500, 400 for both savedObject client
-    // 4xx errors, and other errors
+    // Cast all 5xx error returned by saveObjectClient to 500.
+    // Case both savedObject client 4xx errors, and other errors to 400
     this.statusCode = SavedObjectsErrorHelpers.isOpenSearchUnavailableError(error) ? 500 : 400;
   }
 }