NR-572481: Document NEW_RELIC_APP_NAME support for Lambda APM mode

src/content/docs/serverless-function-monitoring/aws-lambda-monitoring/instrument-lambda-function/app-name-apm-lambda.mdx

@@ -0,0 +1,40 @@
+---
+title: "NEW_RELIC_APP_NAME for AWS Lambda APM mode"
+metaDescription: "Understand how NEW_RELIC_APP_NAME controls APM entity grouping, multi-region reporting, cross-runtime behavior, and shared naming with non-Lambda services."
+freshnessValidatedDate: never
+tags:
+  - AWS Lambda
+  - APM
+  - Environment Variables
+  - Configuration
+---
+
+When `NEW_RELIC_APM_LAMBDA_MODE` is `true`, the `NEW_RELIC_APP_NAME` environment variable controls how your Lambda functions appear as APM entities in New Relic. This page explains the key behaviors to understand before setting this variable.
+
+## Entity behaviour
+
+Functions sharing the same `NEW_RELIC_APP_NAME` value and New Relic account are grouped under a single APM entity in the New Relic UI.
+
+If the name you set matches an existing APM entity — for example, one already created by a non-Lambda service — telemetry from your Lambda function merges into that entity automatically. There is no separate entity created.
+
+<Callout variant="important">
+  Changing `NEW_RELIC_APP_NAME` creates a new APM entity. Historical data associated with the previous name is not migrated to the new entity.
+</Callout>
+
+## Multi-region reporting
+
+Multiple Lambda functions deployed across different AWS regions can share the same `NEW_RELIC_APP_NAME`. All of these functions report into a single APM entity, regardless of which region they are deployed in.
+
+To distinguish individual functions or region-specific deployments within the grouped entity, filter by the `tags.aws.arn` attribute in NRQL or use the tag filter bar in the entity view.
+
+## Cross-runtime reporting
+
+Lambda functions using different runtimes (for example, a Python function and a Node.js function) that share the same `NEW_RELIC_APP_NAME` create **separate** APM entities — one per runtime. The grouping does not cross runtime boundaries.
+
+## Same app name across Lambda and non-Lambda services
+
+If a Lambda function and a non-Lambda APM service (for example, a traditional web application or microservice) are both configured with the same `NEW_RELIC_APP_NAME`, they report into the **same** APM entity.
+
+This can be intentional: if you want a unified view of a service that runs on both Lambda and server-based infrastructure, sharing the name allows all telemetry — transactions, errors, throughput — to appear in one place.
+
+However, if done unintentionally, it can cause confusion. Metrics, error rates, and throughput from the Lambda function and the non-Lambda service are combined, which may make it harder to diagnose issues or understand performance independently.

src/content/docs/serverless-function-monitoring/aws-lambda-monitoring/instrument-lambda-function/env-variables-lambda.mdx

@@ -109,7 +109,9 @@ Based on your runtime, you can set the following environment variables to furthe
             <td>`NEW_RELIC_APP_NAME`</td>
             <td></td>
             <td></td>
-            <td>Set the application name, though it is not used in the New Relic UI</td>
+            <td>
+                Sets the application name used as the APM entity name in the New Relic UI when `NEW_RELIC_APM_LAMBDA_MODE` is `true`. See [NEW_RELIC_APP_NAME for AWS Lambda APM mode](/docs/serverless-function-monitoring/aws-lambda-monitoring/instrument-lambda-function/app-name-apm-lambda/) for details on entity grouping, multi-region reporting, cross-runtime behaviour, and shared naming with non-Lambda services.
+            </td>
         </tr>
         <tr>
             <td>`NEW_RELIC_LOG_ENABLED`</td>
@@ -167,7 +169,9 @@ You can find more environment variables in our [Node.js configuration documentat
             <td>`NEW_RELIC_APP_NAME`</td>
             <td></td>
             <td></td>
-            <td>Set the application name, though it is not used in the New Relic UI</td>
+            <td>
+                Sets the application name used as the APM entity name in the New Relic UI when `NEW_RELIC_APM_LAMBDA_MODE` is `true`. See [NEW_RELIC_APP_NAME for AWS Lambda APM mode](/docs/serverless-function-monitoring/aws-lambda-monitoring/instrument-lambda-function/app-name-apm-lambda/) for details on entity grouping, multi-region reporting, cross-runtime behaviour, and shared naming with non-Lambda services.
+            </td>
         </tr>
         <tr>
             <td>`NEW_RELIC_LOG`</td>
@@ -253,6 +257,14 @@ You can find more environment variables in our [Python configuration documentati
             <td>`true`, `false`</td>
             <td>Enable debug logging by setting this to `true`</td>
         </tr>
+        <tr>
+            <td>`NEW_RELIC_APP_NAME`</td>
+            <td></td>
+            <td></td>
+            <td>
+                Sets the application name used as the APM entity name in the New Relic UI when `NEW_RELIC_APM_LAMBDA_MODE` is `true`. See [NEW_RELIC_APP_NAME for AWS Lambda APM mode](/docs/serverless-function-monitoring/aws-lambda-monitoring/instrument-lambda-function/app-name-apm-lambda/) for details on entity grouping, multi-region reporting, cross-runtime behaviour, and shared naming with non-Lambda services.
+            </td>
+        </tr>
     </tbody>
 </table>
 
@@ -279,7 +291,9 @@ You can find more environment variables in our [Java agent configuration documen
             <td>`NEW_RELIC_APP_NAME`</td>
             <td></td>
             <td></td>
-            <td>Set the application name, though it is not used in the New Relic UI</td>
+            <td>
+                Sets the application name used as the APM entity name in the New Relic UI when `NEW_RELIC_APM_LAMBDA_MODE` is `true`. See [NEW_RELIC_APP_NAME for AWS Lambda APM mode](/docs/serverless-function-monitoring/aws-lambda-monitoring/instrument-lambda-function/app-name-apm-lambda/) for details on entity grouping, multi-region reporting, cross-runtime behaviour, and shared naming with non-Lambda services.
+            </td>
         </tr>
         <tr>
             <td>`NEW_RELIC_LOG`</td>
@@ -313,6 +327,14 @@ You can find more environment variables in our [Java agent configuration documen
             <td>`true`, `false`</td>
             <td>Generate traces by enabling Distributed Tracing</td>
         </tr>
+        <tr>
+            <td>`NEW_RELIC_APP_NAME`</td>
+            <td></td>
+            <td></td>
+            <td>
+                Sets the application name used as the APM entity name in the New Relic UI when `NEW_RELIC_APM_LAMBDA_MODE` is `true`. See [NEW_RELIC_APP_NAME for AWS Lambda APM mode](/docs/serverless-function-monitoring/aws-lambda-monitoring/instrument-lambda-function/app-name-apm-lambda/) for details on entity grouping, multi-region reporting, cross-runtime behaviour, and shared naming with non-Lambda services.
+            </td>
+        </tr>
     </tbody>
 </table>
 </TabsPageItem>
@@ -363,7 +385,9 @@ You can find more environment variables in our [Java agent configuration documen
             <td>`NEW_RELIC_APP_NAME`</td>
             <td></td>
             <td></td>
-            <td>Set the application name, though it is not used in the New Relic UI</td>
+            <td>
+                Sets the application name used as the APM entity name in the New Relic UI when `NEW_RELIC_APM_LAMBDA_MODE` is `true`. See [NEW_RELIC_APP_NAME for AWS Lambda APM mode](/docs/serverless-function-monitoring/aws-lambda-monitoring/instrument-lambda-function/app-name-apm-lambda/) for details on entity grouping, multi-region reporting, cross-runtime behaviour, and shared naming with non-Lambda services.
+            </td>
         </tr>
         <tr>
             <td>`NEW_RELIC_LOG_ENABLED`</td>
@@ -399,6 +423,14 @@ You can find more environment variables in our [.NET configuration documentation
         </tr>
     </thead>
     <tbody>
+        <tr>
+            <td>`NEW_RELIC_APP_NAME`</td>
+            <td></td>
+            <td></td>
+            <td>
+                When `NEW_RELIC_APM_LAMBDA_MODE` is `true`, the extension uses this value as the APM entity name during the cold-start connect call. See [NEW_RELIC_APP_NAME for AWS Lambda APM mode](/docs/serverless-function-monitoring/aws-lambda-monitoring/instrument-lambda-function/app-name-apm-lambda/) for details on entity grouping, multi-region reporting, cross-runtime behaviour, and shared naming with non-Lambda services.
+            </td>
+        </tr>
         <tr>
             <td>`NEW_RELIC_LAMBDA_EXTENSION_ENABLED`</td>
             <td>`true`</td>