Azure Monitor: Fix metric metadata retrieval based on template variables (#60674)

public/app/plugins/datasource/grafana-azure-monitor-datasource/azure_monitor/azure_monitor_datasource.test.ts

@@ -307,6 +307,30 @@ describe('AzureMonitorDatasource', () => {
           expect(results.supportedTimeGrains.length).toEqual(5); // 4 time grains from the API + auto
         });
     });
+
+    it('should replace a template variable for the metric name', () => {
+      templateSrv.init([
+        {
+          id: 'metric',
+          name: 'metric',
+          current: {
+            value: 'UsedCapacity',
+          },
+        },
+      ]);
+      return ctx.ds.azureMonitorDatasource
+        .getMetricMetadata({
+          resourceUri:
+            '/subscriptions/mock-subscription-id/resourceGroups/nodeapp/providers/microsoft.insights/components/resource1',
+          metricNamespace: 'microsoft.insights/components',
+          metricName: '$metric',
+        })
+        .then((results) => {
+          expect(results.primaryAggType).toEqual('Total');
+          expect(results.supportedAggTypes.length).toEqual(6);
+          expect(results.supportedTimeGrains.length).toEqual(5); // 4 time grains from the API + auto
+        });
+    });
   });
 
   describe('When performing interpolateVariablesInQueries for azure_monitor_metrics', () => {

public/app/plugins/datasource/grafana-azure-monitor-datasource/azure_monitor/azure_monitor_datasource.ts

@@ -260,7 +260,7 @@ export default class AzureMonitorDatasource extends DataSourceWithBackend<AzureM
       this.templateSrv
     );
     return this.getResource(url).then((result: AzureMonitorMetricsMetadataResponse) => {
-      return ResponseParser.parseMetadata(result, metricName);
+      return ResponseParser.parseMetadata(result, this.templateSrv.replace(metricName));
     });
   }