Google Cloud Monitoring: Fix bucket bound for distributions (#56565)

pkg/tsdb/cloudmonitoring/cloudmonitoring.go

@@ -596,7 +596,12 @@ func calcBucketBound(bucketOptions cloudMonitoringBucketOptions, n int) string {
 	case bucketOptions.ExponentialBuckets != nil:
 		bucketBound = strconv.FormatInt(int64(bucketOptions.ExponentialBuckets.Scale*math.Pow(bucketOptions.ExponentialBuckets.GrowthFactor, float64(n-1))), 10)
 	case bucketOptions.ExplicitBuckets != nil:
-		bucketBound = fmt.Sprintf("%g", bucketOptions.ExplicitBuckets.Bounds[n])
+		if n < len(bucketOptions.ExplicitBuckets.Bounds) {
+			bucketBound = fmt.Sprintf("%g", bucketOptions.ExplicitBuckets.Bounds[n])
+		} else {
+			lastBound := bucketOptions.ExplicitBuckets.Bounds[len(bucketOptions.ExplicitBuckets.Bounds)-1]
+			bucketBound = fmt.Sprintf("%g+", lastBound)
+		}
 	}
 	return bucketBound
 }

pkg/tsdb/cloudmonitoring/test-data/4-series-response-distribution-explicit.json

@@ -103,7 +103,16 @@
                 "4",
                 "7",
                 "12",
-                "8"
+                "8",
+                "0",
+                "0",
+                "0",
+                "0",
+                "0",
+                "0",
+                "0",
+                "0",
+                "0"
               ]
             }
           }
@@ -198,7 +207,16 @@
                 "5",
                 "7",
                 "11",
-                "8"
+                "8",
+                "0",
+                "0",
+                "0",
+                "0",
+                "0",
+                "0",
+                "0",
+                "0",
+                "0"
               ]
             }
           }

pkg/tsdb/cloudmonitoring/time_series_filter_test.go

@@ -185,8 +185,8 @@ func TestTimeSeriesFilter(t *testing.T) {
 		require.NoError(t, err)
 		frames := res.Frames
 		require.NoError(t, err)
-		assert.Equal(t, 33, len(frames))
-		for i := 0; i < 33; i++ {
+		assert.Equal(t, 42, len(frames))
+		for i := 0; i < 42; i++ {
 			if i == 0 {
 				assert.Equal(t, "0", frames[i].Fields[1].Name)
 			}