Annotations: Fix min step parameter interpolation in Prometheus annotations query (#97734)

* Fix `min step` parameter interpolation in prometheus annotations query

Looks like the step is interpolated in annotationQuery, but not interpolated in processAnnotationResponse. Fixing that.

* Update packages/grafana-prometheus/src/datasource.ts

Co-authored-by: Brendan O'Handley <brendan.ohandley@grafana.com>

* Added test for non-default step

* modified tests

* apply prettier manually

---------

Co-authored-by: Brendan O'Handley <brendan.ohandley@grafana.com>

packages/grafana-prometheus/src/datasource.test.ts

@@ -1051,9 +1051,13 @@ describe('PrometheusDatasource2', () => {
         },
       } as unknown as AnnotationQueryRequest;
 
-      async function runAnnotationQuery(data: number[][]) {
+      async function runAnnotationQuery(data: number[][], overrideStep?: string) {
         let response = createAnnotationResponse();
         response.data.results['X'].frames[0].data.values = data;
+        if (overrideStep) {
+          const meta = response.data.results['X'].frames[0].schema.meta;
+          meta.executedQueryString = meta.executedQueryString.replace('1m0s', overrideStep);
+        }
 
         options.annotation.useValueForTime = false;
         fetchMock.mockImplementation(() => of(response));
@@ -1093,6 +1097,31 @@ describe('PrometheusDatasource2', () => {
         const results = await runAnnotationQuery([[2 * 60000], [1]]);
         expect(results.map((result) => [result.time, result.timeEnd])).toEqual([[120000, 120000]]);
       });
+
+      describe('should group annotations over wider range when the step grows larger', () => {
+        const data: number[][] = [
+          [1 * 120000, 2 * 120000, 3 * 120000, 4 * 120000, 5 * 120000, 6 * 120000],
+          [1, 1, 0, 0, 1, 1],
+        ];
+
+        it('should not group annotations with the default step', async () => {
+          const results = await runAnnotationQuery(data);
+          expect(results.map((result) => [result.time, result.timeEnd])).toEqual([
+            [120000, 120000],
+            [240000, 240000],
+            [600000, 600000],
+            [720000, 720000],
+          ]);
+        });
+
+        it('should group annotations with larger step', async () => {
+          const results = await runAnnotationQuery(data, '2m0s');
+          expect(results.map((result) => [result.time, result.timeEnd])).toEqual([
+            [120000, 240000],
+            [600000, 720000],
+          ]);
+        });
+      });
     });
 
     describe('with template variables', () => {

packages/grafana-prometheus/src/datasource.ts

@@ -537,7 +537,11 @@ export class PrometheusDatasource
     const annotation = options.annotation;
     const { tagKeys = '', titleFormat = '', textFormat = '' } = annotation;
 
-    const step = rangeUtil.intervalToSeconds(annotation.step || ANNOTATION_QUERY_STEP_DEFAULT) * 1000;
+    const input = frames[0].meta?.executedQueryString || '';
+    const regex = /Step:\s*([\d\w]+)/;
+    const match = input.match(regex);
+    const stepValue = match ? match[1] : null;
+    const step = rangeUtil.intervalToSeconds(stepValue || ANNOTATION_QUERY_STEP_DEFAULT) * 1000;
     const tagKeysArray = tagKeys.split(',');
 
     const eventList: AnnotationEvent[] = [];

packages/grafana-prometheus/src/test/__mocks__/datasource.ts

@@ -108,6 +108,10 @@ export function createAnnotationResponse() {
               schema: {
                 name: 'bar',
                 refId: 'X',
+                meta: {
+                  typeVersion: [0, 0],
+                  executedQueryString: 'Expr: ALERTS{}\nStep: 1m0s',
+                },
                 fields: [
                   {
                     name: 'Time',