[Monitor OpenTelemetry Exporter] Add KUBERNETES_SERVICE_HOST Detection (#36660)

### Packages impacted by this PR
@azure/monitor-opentelemetry-exporter

### Describe the problem that is addressed by this PR
This pull request improves AKS (Azure Kubernetes Service) detection in
the `monitor-opentelemetry-exporter` package by updating the logic to
recognize AKS environments when the `KUBERNETES_SERVICE_HOST`
environment variable is present. This change helps ensure that the
exporter correctly identifies AKS deployments even if
`AKS_ARM_NAMESPACE_ID` is not set.

**AKS detection improvements:**

* Updated `StatsbeatMetrics#getResourceProvider` in
`statsbeatMetrics.ts` to detect AKS when either `AKS_ARM_NAMESPACE_ID`
or `KUBERNETES_SERVICE_HOST` is defined, and set the resource identifier
accordingly.
* Documented the AKS detection enhancement in the `CHANGELOG.md` for the
upcoming `1.0.0-beta.37` release.

### What are the possible designs available to address the problem? If
there are more than one possible design, why was the one in this PR
chosen?

### Checklists
- [x] Added impacted package name to the issue description
- [ ] Does this PR needs any fixes in the SDK Generator?** _(If so,
create an Issue in the
[Autorest/typescript](https://github.com/Azure/autorest.typescript)
repository and link it here)_
- [x] Added a changelog (if necessary)

Author: JacksonWeber

sdk/monitor/monitor-opentelemetry-exporter/CHANGELOG.md

@@ -1,5 +1,17 @@
 # Release History
 
+### 1.0.0-beta.37 ()
+
+### Features Added
+
+### Bugs Fixed
+
+### Breaking Changes
+
+### Other Changes
+
+- Detect AKS when the `KUBERNETES_SERVICE_HOST` environment variable is defined.
+
 ## 1.0.0-beta.36 (2025-11-10)
 
 ### Bugs Fixed

sdk/monitor/monitor-opentelemetry-exporter/src/export/statsbeat/statsbeatMetrics.ts

@@ -25,10 +25,11 @@ export class StatsbeatMetrics {
   protected async getResourceProvider(): Promise<void> {
     // Check resource provider
     this.resourceProvider = StatsbeatResourceProvider.unknown;
-    if (process.env.AKS_ARM_NAMESPACE_ID) {
+    if (process.env.AKS_ARM_NAMESPACE_ID || process.env.KUBERNETES_SERVICE_HOST) {
       // AKS
       this.resourceProvider = StatsbeatResourceProvider.aks;
-      this.resourceIdentifier = process.env.AKS_ARM_NAMESPACE_ID;
+      this.resourceIdentifier =
+        process.env.AKS_ARM_NAMESPACE_ID || process.env.KUBERNETES_SERVICE_HOST || "";
     } else if (process.env.WEBSITE_SITE_NAME && !process.env.FUNCTIONS_WORKER_RUNTIME) {
       // Web apps
       this.resourceProvider = StatsbeatResourceProvider.appsvc;

sdk/monitor/monitor-opentelemetry-exporter/test/internal/statsbeat.spec.ts

@@ -292,7 +292,7 @@ describe("#AzureMonitorStatsbeatExporter", () => {
         assert.strictEqual(statsbeat["resourceIdentifier"], "undefined/undefined");
       });
 
-      it("should determine if the rp is AKS", async () => {
+      it("should determine if the rp is AKS with AKS_ARM_NAMESPACE_ID", async () => {
         const newEnv = <{ [id: string]: string }>{};
         newEnv["AKS_ARM_NAMESPACE_ID"] = "testaks";
         const originalEnv = process.env;
@@ -304,6 +304,31 @@ describe("#AzureMonitorStatsbeatExporter", () => {
         assert.strictEqual(statsbeat["resourceIdentifier"], "testaks");
       });
 
+      it("should determine if the rp is AKS with KUBERNETES_SERVICE_HOST", async () => {
+        const newEnv = <{ [id: string]: string }>{};
+        newEnv["KUBERNETES_SERVICE_HOST"] = "10.0.0.1";
+        const originalEnv = process.env;
+        process.env = newEnv;
+
+        await statsbeat["getResourceProvider"]();
+        process.env = originalEnv;
+        assert.strictEqual(statsbeat["resourceProvider"], "aks");
+        assert.strictEqual(statsbeat["resourceIdentifier"], "10.0.0.1");
+      });
+
+      it("should prioritize AKS_ARM_NAMESPACE_ID over KUBERNETES_SERVICE_HOST when both are present", async () => {
+        const newEnv = <{ [id: string]: string }>{};
+        newEnv["AKS_ARM_NAMESPACE_ID"] = "testaks";
+        newEnv["KUBERNETES_SERVICE_HOST"] = "10.0.0.1";
+        const originalEnv = process.env;
+        process.env = newEnv;
+
+        await statsbeat["getResourceProvider"]();
+        process.env = originalEnv;
+        assert.strictEqual(statsbeat["resourceProvider"], "aks");
+        assert.strictEqual(statsbeat["resourceIdentifier"], "testaks");
+      });
+
       it("should override OS and VM info", async () => {
         const getAzureComputeStub = vi.spyOn(statsbeat, "getAzureComputeMetadata");
         getAzureComputeStub.mockResolvedValue(true);
@@ -459,7 +484,7 @@ describe("#AzureMonitorStatsbeatExporter", () => {
       });
 
       describe("Priority and edge cases", () => {
-        it("should prioritize AKS detection over App Service", async () => {
+        it("should prioritize AKS detection with AKS_ARM_NAMESPACE_ID over App Service", async () => {
           const newEnv = <{ [id: string]: string }>{};
           newEnv["AKS_ARM_NAMESPACE_ID"] =
             "/subscriptions/test/resourceGroups/test/providers/Microsoft.ContainerService/managedClusters/test-aks";
@@ -477,6 +502,36 @@ describe("#AzureMonitorStatsbeatExporter", () => {
           );
         });
 
+        it("should prioritize AKS detection with KUBERNETES_SERVICE_HOST over App Service", async () => {
+          const newEnv = <{ [id: string]: string }>{};
+          newEnv["KUBERNETES_SERVICE_HOST"] = "10.0.0.1";
+          newEnv["WEBSITE_SITE_NAME"] = "my-webapp";
+          const originalEnv = process.env;
+          process.env = newEnv;
+
+          await statsbeat["getResourceProvider"]();
+
+          process.env = originalEnv;
+          assert.strictEqual(statsbeat["resourceProvider"], "aks");
+          assert.strictEqual(statsbeat["resourceIdentifier"], "10.0.0.1");
+        });
+
+        it("should prioritize AKS detection with KUBERNETES_SERVICE_HOST over Functions", async () => {
+          const newEnv = <{ [id: string]: string }>{};
+          newEnv["KUBERNETES_SERVICE_HOST"] = "10.0.0.1";
+          newEnv["WEBSITE_SITE_NAME"] = "my-function-app";
+          newEnv["FUNCTIONS_WORKER_RUNTIME"] = "node";
+          newEnv["WEBSITE_HOSTNAME"] = "my-function-app.azurewebsites.net";
+          const originalEnv = process.env;
+          process.env = newEnv;
+
+          await statsbeat["getResourceProvider"]();
+
+          process.env = originalEnv;
+          assert.strictEqual(statsbeat["resourceProvider"], "aks");
+          assert.strictEqual(statsbeat["resourceIdentifier"], "10.0.0.1");
+        });
+
         it("should prioritize Functions detection over App Service when both conditions are met", async () => {
           const newEnv = <{ [id: string]: string }>{};
           newEnv["WEBSITE_SITE_NAME"] = "my-function-app";