Datasource/Loki: Loki now goes to Logs mode when importing prom queries (#20890)

* Datasource/Loki: Loki now goes to Logs mode when importing prom queries
Closes #20831

* Fixes behavior and adds tests

* Update public/app/features/explore/state/actions.test.ts

public/app/features/explore/state/actionTypes.ts

@@ -178,6 +178,7 @@ export interface UpdateDatasourceInstancePayload {
   exploreId: ExploreId;
   datasourceInstance: DataSourceApi;
   version?: string;
+  mode?: ExploreMode;
 }
 
 export interface ToggleLogLevelPayload {

public/app/features/explore/state/actions.test.ts

-import { loadDatasource, navigateToExplore, refreshExplore } from './actions';
+import { changeDatasource, loadDatasource, navigateToExplore, refreshExplore } from './actions';
+import * as Actions from './actions';
 import { ExploreId, ExploreMode, ExploreUpdateState, ExploreUrlState } from 'app/types';
 import { thunkTester } from 'test/core/thunk/thunkTester';
 import {
@@ -8,6 +9,7 @@ import {
   loadDatasourceReadyAction,
   setQueriesAction,
   updateUIStateAction,
+  updateDatasourceInstanceAction,
 } from './actionTypes';
 import { Emitter } from 'app/core/core';
 import { ActionOf } from 'app/core/redux/actionCreatorFactory';
@@ -16,16 +18,24 @@ import { DataQuery, DefaultTimeZone, LogsDedupStrategy, RawTimeRange, toUtc } fr
 import { PanelModel } from 'app/features/dashboard/state';
 import { updateLocation } from '../../../core/actions';
 import { MockDataSourceApi } from '../../../../test/mocks/datasource_srv';
-
-jest.mock('app/features/plugins/datasource_srv', () => ({
-  getDatasourceSrv: () => ({
-    getExternal: jest.fn().mockReturnValue([]),
-    get: jest.fn().mockReturnValue({
-      testDatasource: jest.fn(),
-      init: jest.fn(),
-    }),
-  }),
-}));
+import * as DatasourceSrv from 'app/features/plugins/datasource_srv';
+
+jest.mock('app/features/plugins/datasource_srv');
+const getDatasourceSrvMock = (DatasourceSrv.getDatasourceSrv as any) as jest.Mock<DatasourceSrv.DatasourceSrv>;
+
+beforeEach(() => {
+  getDatasourceSrvMock.mockClear();
+  getDatasourceSrvMock.mockImplementation(
+    () =>
+      ({
+        getExternal: jest.fn().mockReturnValue([]),
+        get: jest.fn().mockReturnValue({
+          testDatasource: jest.fn(),
+          init: jest.fn(),
+        }),
+      } as any)
+  );
+});
 
 jest.mock('../../dashboard/services/TimeSrv', () => ({
   getTimeSrv: jest.fn().mockReturnValue({
@@ -163,6 +173,62 @@ describe('refreshExplore', () => {
   });
 });
 
+describe('changing datasource', () => {
+  it('should switch to logs mode when changing from prometheus to loki', async () => {
+    const lokiMock = {
+      testDatasource: () => Promise.resolve({ status: 'success' }),
+      name: 'Loki',
+      init: jest.fn(),
+      meta: { id: 'some id', name: 'Loki' },
+    };
+
+    getDatasourceSrvMock.mockImplementation(
+      () =>
+        ({
+          getExternal: jest.fn().mockReturnValue([]),
+          get: jest.fn().mockReturnValue(lokiMock),
+        } as any)
+    );
+
+    const exploreId = ExploreId.left;
+    const name = 'Prometheus';
+    const mockPromDatasourceInstance = {
+      testDatasource: () => Promise.resolve({ status: 'success' }),
+      name,
+      init: jest.fn(),
+      meta: { id: 'some id', name },
+    };
+
+    const initialState = {
+      explore: {
+        [exploreId]: {
+          requestedDatasourceName: 'Loki',
+          datasourceInstance: mockPromDatasourceInstance,
+        },
+      },
+      user: {
+        orgId: 1,
+      },
+    };
+
+    jest.spyOn(Actions, 'importQueries').mockImplementationOnce(() => jest.fn);
+    jest.spyOn(Actions, 'loadDatasource').mockImplementationOnce(() => jest.fn);
+    jest.spyOn(Actions, 'runQueries').mockImplementationOnce(() => jest.fn);
+    const dispatchedActions = await thunkTester(initialState)
+      .givenThunk(changeDatasource)
+      .whenThunkIsDispatched(exploreId, name);
+
+    expect(dispatchedActions).toEqual([
+      updateDatasourceInstanceAction({
+        exploreId,
+        datasourceInstance: lokiMock as any,
+        version: undefined,
+        mode: ExploreMode.Logs,
+      }),
+    ]);
+  });
+});
+
 describe('loading datasource', () => {
   describe('when loadDatasource thunk is dispatched', () => {
     describe('and all goes fine', () => {

public/app/features/explore/state/actions.ts

@@ -124,11 +124,16 @@ export function changeDatasource(exploreId: ExploreId, datasource: string): Thun
     const orgId = getState().user.orgId;
     const datasourceVersion = newDataSourceInstance.getVersion && (await newDataSourceInstance.getVersion());
 
+    // HACK: Switch to logs mode if coming from Prometheus to Loki
+    const prometheusToLoki =
+      currentDataSourceInstance?.meta?.name === 'Prometheus' && newDataSourceInstance?.meta?.name === 'Loki';
+
     dispatch(
       updateDatasourceInstanceAction({
         exploreId,
         datasourceInstance: newDataSourceInstance,
         version: datasourceVersion,
+        mode: prometheusToLoki ? ExploreMode.Logs : undefined,
       })
     );
 
@@ -316,12 +321,12 @@ export const loadDatasourceReady = (
  * @param sourceDataSource
  * @param targetDataSource
  */
-export function importQueries(
+export const importQueries = (
   exploreId: ExploreId,
   queries: DataQuery[],
   sourceDataSource: DataSourceApi,
   targetDataSource: DataSourceApi
-): ThunkResult<void> {
+): ThunkResult<void> => {
   return async dispatch => {
     if (!sourceDataSource) {
       // explore not initialized
@@ -346,12 +351,12 @@ export function importQueries(
 
     dispatch(queriesImportedAction({ exploreId, queries: nextQueries }));
   };
-}
+};
 
 /**
  * Main action to asynchronously load a datasource. Dispatches lots of smaller actions for feedback.
  */
-export function loadDatasource(exploreId: ExploreId, instance: DataSourceApi, orgId: number): ThunkResult<void> {
+export const loadDatasource = (exploreId: ExploreId, instance: DataSourceApi, orgId: number): ThunkResult<void> => {
   return async (dispatch, getState) => {
     const datasourceName = instance.name;
 
@@ -373,7 +378,7 @@ export function loadDatasource(exploreId: ExploreId, instance: DataSourceApi, or
 
     dispatch(loadDatasourceReady(exploreId, instance, orgId));
   };
-}
+};
 
 /**
  * Action to modify a query given a datasource-specific modifier action.
@@ -399,7 +404,7 @@ export function modifyQueries(
 /**
  * Main action to run queries and dispatches sub-actions based on which result viewers are active
  */
-export function runQueries(exploreId: ExploreId): ThunkResult<void> {
+export const runQueries = (exploreId: ExploreId): ThunkResult<void> => {
   return (dispatch, getState) => {
     dispatch(updateTime({ exploreId }));
 
@@ -484,7 +489,7 @@ export function runQueries(exploreId: ExploreId): ThunkResult<void> {
 
     dispatch(queryStoreSubscriptionAction({ exploreId, querySubscription: newQuerySub }));
   };
-}
+};
 
 const toRawTimeRange = (range: TimeRange): RawTimeRange => {
   let from = range.raw.from;

public/app/features/explore/state/reducers.ts

@@ -269,7 +269,7 @@ export const itemReducer = reducerFactory<ExploreItemState>({} as ExploreItemSta
   .addMapper({
     filter: updateDatasourceInstanceAction,
     mapper: (state, action): ExploreItemState => {
-      const { datasourceInstance, version } = action.payload;
+      const { datasourceInstance, version, mode } = action.payload;
 
       // Custom components
       stopQueryState(state.querySubscription);
@@ -291,7 +291,7 @@ export const itemReducer = reducerFactory<ExploreItemState>({} as ExploreItemSta
       }
 
       const updatedDatasourceInstance = Object.assign(datasourceInstance, { meta: newMetadata });
-      const [supportedModes, mode] = getModesForDatasource(updatedDatasourceInstance, state.mode);
+      const [supportedModes, newMode] = getModesForDatasource(updatedDatasourceInstance, state.mode);
 
       return {
         ...state,
@@ -304,7 +304,7 @@ export const itemReducer = reducerFactory<ExploreItemState>({} as ExploreItemSta
         loading: false,
         queryKeys: [],
         supportedModes,
-        mode,
+        mode: mode ?? newMode,
         originPanelId: state.urlState && state.urlState.originPanelId,
       };
     },

public/app/features/plugins/datasource_srv.ts

@@ -190,9 +190,9 @@ export class DatasourceSrv implements DataSourceService {
   }
 }
 
-export function getDatasourceSrv(): DatasourceSrv {
+export const getDatasourceSrv = (): DatasourceSrv => {
   return getDataSourceService() as DatasourceSrv;
-}
+};
 
 coreModule.service('datasourceSrv', DatasourceSrv);
 export default DatasourceSrv;