AzureMonitor: Improve resource picker efficiency (#93127)

* Parameterise region building metric namespace URL

- Add parameter for region (this parameter takes precedence over if global is set)
- Update tests
- Support this parameter on the data source method

* Refactor fetchAllNamespaces

- Use Set rather than an array for greater performance
- Request namespaces across WestEurope, EastUS, and JapanEast concurrently
- Update test

* Maintain existing behaviour

public/app/plugins/datasource/azuremonitor/azure_monitor/azure_monitor_datasource.ts

@@ -231,14 +231,15 @@ export default class AzureMonitorDatasource extends DataSourceWithBackend<AzureM
     return (await Promise.all(promises)).flat();
   }
 
-  getMetricNamespaces(query: GetMetricNamespacesQuery, globalRegion: boolean) {
+  getMetricNamespaces(query: GetMetricNamespacesQuery, globalRegion: boolean, region?: string) {
     const url = UrlBuilder.buildAzureMonitorGetMetricNamespacesUrl(
       this.resourcePath,
       this.apiPreviewVersion,
       // Only use the first query, as the metric namespaces should be the same for all queries
       this.replaceSingleTemplateVariables(query),
       globalRegion,
-      this.templateSrv
+      this.templateSrv,
+      region
     );
     return this.getResource(url)
       .then((result: AzureAPIResponse<Namespace>) => {

public/app/plugins/datasource/azuremonitor/azure_monitor/url_builder.test.ts

@@ -142,6 +142,38 @@ describe('AzureMonitorUrlBuilder', () => {
         '/subscriptions/sub/resource-uri/resource/providers/microsoft.insights/metricNamespaces?api-version=2017-05-01-preview&region=global'
       );
     });
+
+    it('builds a getMetricNamesnamespace url with a specific region', () => {
+      const url = UrlBuilder.buildAzureMonitorGetMetricNamespacesUrl(
+        '',
+        '2017-05-01-preview',
+        {
+          resourceUri: '/subscriptions/sub/resource-uri/resource',
+        },
+        false,
+        templateSrv,
+        'testregion'
+      );
+      expect(url).toBe(
+        '/subscriptions/sub/resource-uri/resource/providers/microsoft.insights/metricNamespaces?api-version=2017-05-01-preview&region=testregion'
+      );
+    });
+
+    it('builds a getMetricNamesnamespace url with a specific region (overriding global)', () => {
+      const url = UrlBuilder.buildAzureMonitorGetMetricNamespacesUrl(
+        '',
+        '2017-05-01-preview',
+        {
+          resourceUri: '/subscriptions/sub/resource-uri/resource',
+        },
+        true,
+        templateSrv,
+        'testregion'
+      );
+      expect(url).toBe(
+        '/subscriptions/sub/resource-uri/resource/providers/microsoft.insights/metricNamespaces?api-version=2017-05-01-preview&region=testregion'
+      );
+    });
   });
 
   describe('when a resource uri and metric namespace is provided', () => {

public/app/plugins/datasource/azuremonitor/azure_monitor/url_builder.ts

@@ -51,7 +51,8 @@ export default class UrlBuilder {
     apiVersion: string,
     query: GetMetricNamespacesQuery,
     globalRegion: boolean,
-    templateSrv: TemplateSrv
+    templateSrv: TemplateSrv,
+    region?: string
   ) {
     let resourceUri: string;
 
@@ -68,7 +69,7 @@ export default class UrlBuilder {
     }
 
     return `${baseUrl}${resourceUri}/providers/microsoft.insights/metricNamespaces?api-version=${apiVersion}${
-      globalRegion ? '&region=global' : ''
+      region ? `&region=${region}` : globalRegion ? '&region=global' : ''
     }`;
   }
 

public/app/plugins/datasource/azuremonitor/resourcePicker/resourcePickerData.test.ts

@@ -312,9 +312,33 @@ describe('AzureMonitor resourcePickerData', () => {
           },
         ],
       };
-      const { resourcePickerData, postResource } = createResourcePickerData([mockSubscriptionsResponse, mockResponse]);
+      const { resourcePickerData, postResource, mockDatasource } = createResourcePickerData([
+        mockSubscriptionsResponse,
+        mockResponse,
+      ]);
       const formattedResults = await resourcePickerData.search('vmname', 'metrics');
-      expect(postResource).toBeCalledTimes(2);
+      expect(postResource).toHaveBeenCalledTimes(2);
+      expect(mockDatasource.azureMonitorDatasource.getMetricNamespaces).toHaveBeenCalledWith(
+        {
+          resourceUri: '/subscriptions/1',
+        },
+        false,
+        'westeurope'
+      );
+      expect(mockDatasource.azureMonitorDatasource.getMetricNamespaces).toHaveBeenCalledWith(
+        {
+          resourceUri: '/subscriptions/1',
+        },
+        false,
+        'eastus'
+      );
+      expect(mockDatasource.azureMonitorDatasource.getMetricNamespaces).toHaveBeenCalledWith(
+        {
+          resourceUri: '/subscriptions/1',
+        },
+        false,
+        'japaneast'
+      );
       const secondCall = postResource.mock.calls[1];
       const [_, postBody] = secondCall;
       expect(postBody.query).not.toContain('union resourcecontainers');

public/app/plugins/datasource/azuremonitor/resourcePicker/resourcePickerData.ts

@@ -1,5 +1,3 @@
-import { uniq } from 'lodash';
-
 import { DataSourceInstanceSettings } from '@grafana/data';
 import { DataSourceWithBackend, reportInteraction } from '@grafana/runtime';
 
@@ -359,28 +357,40 @@ export default class ResourcePickerData extends DataSourceWithBackend<AzureMonit
   private async fetchAllNamespaces() {
     const subscriptions = await this.getSubscriptions();
     reportInteraction('grafana_ds_azuremonitor_subscriptions_loaded', { subscriptions: subscriptions.length });
-    let supportedMetricNamespaces: string[] = [];
-    for await (const subscription of subscriptions) {
+
+    let supportedMetricNamespaces: Set<string> = new Set();
+    // We make use of these three regions as they *should* contain every possible namespace
+    const regions = ['westeurope', 'eastus', 'japaneast'];
+    const getNamespacesForRegion = async (region: string) => {
       const namespaces = await this.azureMonitorDatasource.getMetricNamespaces(
         {
-          resourceUri: `/subscriptions/${subscription.id}`,
+          // We only need to run this request against the first available subscription
+          resourceUri: `/subscriptions/${subscriptions[0].id}`,
         },
-        true
+        false,
+        region
       );
       if (namespaces) {
-        const namespaceVals = namespaces.map((namespace) => `"${namespace.value.toLocaleLowerCase()}"`);
-        supportedMetricNamespaces = supportedMetricNamespaces.concat(namespaceVals);
+        for (const namespace of namespaces) {
+          supportedMetricNamespaces.add(`"${namespace.value.toLocaleLowerCase()}"`);
+        }
       }
-    }
+    };
 
-    if (supportedMetricNamespaces.length === 0) {
+    const promises = regions.map((region) => getNamespacesForRegion(region));
+    await Promise.all(promises);
+
+    if (supportedMetricNamespaces.size === 0) {
       throw new Error(
         'Unable to resolve a list of valid metric namespaces. Validate the datasource configuration is correct and required permissions have been granted for all subscriptions. Grafana requires at least the Reader role to be assigned.'
       );
     }
-    this.supportedMetricNamespaces = uniq(
-      supportedMetricNamespaces.concat(resourceTypes.map((namespace) => `"${namespace}"`))
-    ).join(',');
+
+    resourceTypes.forEach((namespace) => {
+      supportedMetricNamespaces.add(`"${namespace}"`);
+    });
+
+    this.supportedMetricNamespaces = Array.from(supportedMetricNamespaces).join(',');
   }
 
   parseRows(resources: Array<string | AzureMonitorResource>): ResourceRow[] {