Plugins: Implement testDatasource for Jaeger (#28916)

* Implement testDatasource for Jaeger

* Unit tests

* Run prettier

public/app/plugins/datasource/jaeger/datasource.test.ts

@@ -53,6 +53,103 @@ describe('JaegerDatasource', () => {
   });
 });
 
+describe('when performing testDataSource', () => {
+  describe('and call succeeds', () => {
+    it('should return successfully', async () => {
+      const backendSrvMock = makeTestDatasourceMock(
+        Promise.resolve({
+          statusText: 'OK',
+          status: 200,
+          data: {
+            data: ['service1'],
+          },
+        })
+      );
+
+      await withMockedBackendSrv(backendSrvMock, async () => {
+        const ds = new JaegerDatasource(defaultSettings);
+        const response = await ds.testDatasource();
+        expect(response.status).toEqual('success');
+        expect(response.message).toBe('Data source connected and services found.');
+      });
+    });
+  });
+
+  describe('and call succeeds, but returns no services', () => {
+    it('should display an error', async () => {
+      const backendSrvMock = makeTestDatasourceMock(
+        Promise.resolve({
+          statusText: 'OK',
+          status: 200,
+        })
+      );
+
+      await withMockedBackendSrv(backendSrvMock, async () => {
+        const ds = new JaegerDatasource(defaultSettings);
+        const response = await ds.testDatasource();
+        expect(response.status).toEqual('error');
+        expect(response.message).toBe(
+          'Data source connected, but no services received. Verify that Jaeger is configured properly.'
+        );
+      });
+    });
+  });
+
+  describe('and call returns error with message', () => {
+    it('should return the formatted error', async () => {
+      const backendSrvMock = {
+        datasourceRequest(options: BackendSrvRequest): Promise<any> {
+          return Promise.reject({
+            statusText: 'Not found',
+            status: 404,
+            data: {
+              message: '404 page not found',
+            },
+          });
+        },
+      } as BackendSrv;
+
+      await withMockedBackendSrv(backendSrvMock, async () => {
+        const ds = new JaegerDatasource(defaultSettings);
+        const response = await ds.testDatasource();
+        expect(response.status).toEqual('error');
+        expect(response.message).toBe('Jaeger: Not found. 404. 404 page not found');
+      });
+    });
+  });
+
+  describe('and call returns error without message', () => {
+    it('should return JSON error', async () => {
+      const backendSrvMock = {
+        datasourceRequest(options: BackendSrvRequest): Promise<any> {
+          return Promise.reject({
+            statusText: 'Bad gateway',
+            status: 502,
+            data: {
+              errors: ['Could not connect to Jaeger backend'],
+            },
+          });
+        },
+      } as BackendSrv;
+
+      await withMockedBackendSrv(backendSrvMock, async () => {
+        const ds = new JaegerDatasource(defaultSettings);
+        const response = await ds.testDatasource();
+        expect(response.status).toEqual('error');
+        expect(response.message).toBe('Jaeger: Bad gateway. 502. {"errors":["Could not connect to Jaeger backend"]}');
+      });
+    });
+  });
+});
+
+function makeTestDatasourceMock(result: Promise<any>) {
+  return {
+    datasourceRequest(options: BackendSrvRequest): Promise<any> {
+      return result;
+    },
+  } as BackendSrv;
+}
+
 function makeBackendSrvMock(traceId: string) {
   return {
     datasourceRequest(options: BackendSrvRequest): Promise<any> {

public/app/plugins/datasource/jaeger/datasource.ts

@@ -11,7 +11,7 @@ import {
 } from '@grafana/data';
 import { getBackendSrv, BackendSrvRequest } from '@grafana/runtime';
 import { Observable, from, of } from 'rxjs';
-import { map } from 'rxjs/operators';
+import { catchError, map } from 'rxjs/operators';
 
 import { getTimeSrv, TimeSrv } from 'app/features/dashboard/services/TimeSrv';
 import { serializeParams } from 'app/core/utils/fetch';
@@ -77,7 +77,41 @@ export class JaegerDatasource extends DataSourceApi<JaegerQuery> {
   }
 
   async testDatasource(): Promise<any> {
-    return true;
+    return this._request('/api/services')
+      .pipe(
+        map(res => {
+          const values: any[] = res?.data?.data || [];
+          const testResult =
+            values.length > 0
+              ? { status: 'success', message: 'Data source connected and services found.' }
+              : {
+                  status: 'error',
+                  message:
+                    'Data source connected, but no services received. Verify that Jaeger is configured properly.',
+                };
+          return testResult;
+        }),
+        catchError((err: any) => {
+          let message = 'Jaeger: ';
+          if (err.statusText) {
+            message += err.statusText;
+          } else {
+            message += 'Cannot connect to Jaeger';
+          }
+
+          if (err.status) {
+            message += `. ${err.status}`;
+          }
+
+          if (err.data && err.data.message) {
+            message += `. ${err.data.message}`;
+          } else if (err.data) {
+            message += `. ${JSON.stringify(err.data)}`;
+          }
+          return of({ status: 'error', message: message });
+        })
+      )
+      .toPromise();
   }
 
   getTimeRange(): { start: number; end: number } {