fix: send alert default annotations for missing data alert (#5315)

pkg/query-service/rules/threshold_rule.go

@@ -44,14 +44,25 @@ type ThresholdRule struct {
 	name          string
 	source        string
 	ruleCondition *RuleCondition
+	// evalWindow is the time window used for evaluating the rule
+	// i.e each time we lookback from the current time, we look at data for the last
+	// evalWindow duration
 	evalWindow time.Duration
+	// holdDuration is the duration for which the alert waits before firing
 	holdDuration time.Duration
+	// holds the static set of labels and annotations for the rule
+	// these are the same for all alerts created for this rule
 	labels      labels.Labels
 	annotations labels.Labels
 
+	// preferredChannels is the list of channels to send the alert to
+	// if the rule is triggered
 	preferredChannels []string
 	mtx               sync.Mutex
+
+	// the time it took to evaluate the rule
 	evaluationDuration time.Duration
+	// the timestamp of the last evaluation
 	evaluationTimestamp time.Time
 
 	health RuleHealth
@@ -61,6 +72,10 @@ type ThresholdRule struct {
 	// map of active alerts
 	active map[uint64]*Alert
 
+	// Ever since we introduced the new metrics query builder, the version is "v4"
+	// for all the rules
+	// if the version is "v3", then we use the old querier
+	// if the version is "v4", then we use the new querierV2
 	version string
 	// temporalityMap is a map of metric name to temporality
 	// to avoid fetching temporality for the same metric multiple times
@@ -70,10 +85,18 @@ type ThresholdRule struct {
 
 	opts ThresholdRuleOpts
 
+	// lastTimestampWithDatapoints is the timestamp of the last datapoint we observed
+	// for this rule
+	// this is used for missing data alerts
 	lastTimestampWithDatapoints time.Time
+
+	// Type of the rule
+	// One of ["LOGS_BASED_ALERT", "TRACES_BASED_ALERT", "METRIC_BASED_ALERT", "EXCEPTIONS_BASED_ALERT"]
 	typ string
 
+	// querier is used for alerts created before the introduction of new metrics query builder
 	querier interfaces.Querier
+	// querierV2 is used for alerts created after the introduction of new metrics query builder
 	querierV2 interfaces.Querier
 
 	reader    interfaces.Reader
@@ -942,13 +965,11 @@ func (r *ThresholdRule) Eval(ctx context.Context, ts time.Time, queriers *Querie
 
 		annotations := make(labels.Labels, 0, len(r.annotations))
 		for _, a := range r.annotations {
-			if smpl.IsMissing {
-				if a.Name == labels.AlertDescriptionLabel || a.Name == labels.AlertSummaryLabel {
-					a.Value = labels.AlertMissingData
-				}
-			}
 			annotations = append(annotations, labels.Label{Name: normalizeLabelName(a.Name), Value: expand(a.Value)})
 		}
+		if smpl.IsMissing {
+			lb.Set(labels.AlertNameLabel, "[No data] "+r.Name())
+		}
 
 		// Links with timestamps should go in annotations since labels
 		// is used alert grouping, and we want to group alerts with the same

pkg/query-service/rules/threshold_rule_test.go

@@ -1099,3 +1099,101 @@ func TestThresholdRuleUnitCombinations(t *testing.T) {
 		}
 	}
 }
+
+func TestThresholdRuleNoData(t *testing.T) {
+	postableRule := PostableRule{
+		AlertName:  "Units test",
+		AlertType:  "METRIC_BASED_ALERT",
+		RuleType:   RuleTypeThreshold,
+		EvalWindow: Duration(5 * time.Minute),
+		Frequency:  Duration(1 * time.Minute),
+		RuleCondition: &RuleCondition{
+			CompositeQuery: &v3.CompositeQuery{
+				QueryType: v3.QueryTypeBuilder,
+				BuilderQueries: map[string]*v3.BuilderQuery{
+					"A": {
+						QueryName:    "A",
+						StepInterval: 60,
+						AggregateAttribute: v3.AttributeKey{
+							Key: "signoz_calls_total",
+						},
+						AggregateOperator: v3.AggregateOperatorSumRate,
+						DataSource:        v3.DataSourceMetrics,
+						Expression:        "A",
+					},
+				},
+			},
+			AlertOnAbsent: true,
+		},
+	}
+	fm := featureManager.StartManager()
+	mock, err := cmock.NewClickHouseWithQueryMatcher(nil, &queryMatcherAny{})
+	if err != nil {
+		t.Errorf("an error '%s' was not expected when opening a stub database connection", err)
+	}
+
+	cols := make([]cmock.ColumnType, 0)
+	cols = append(cols, cmock.ColumnType{Name: "value", Type: "Float64"})
+	cols = append(cols, cmock.ColumnType{Name: "attr", Type: "String"})
+	cols = append(cols, cmock.ColumnType{Name: "timestamp", Type: "String"})
+
+	cases := []struct {
+		values       [][]interface{}
+		expectNoData bool
+	}{
+		{
+			values:       [][]interface{}{},
+			expectNoData: true,
+		},
+	}
+
+	for idx, c := range cases {
+		rows := cmock.NewRows(cols, c.values)
+
+		// We are testing the eval logic after the query is run
+		// so we don't care about the query string here
+		queryString := "SELECT any"
+		mock.
+			ExpectQuery(queryString).
+			WillReturnRows(rows)
+		var target float64 = 0
+		postableRule.RuleCondition.CompareOp = ValueIsEq
+		postableRule.RuleCondition.MatchType = AtleastOnce
+		postableRule.RuleCondition.Target = &target
+		postableRule.Annotations = map[string]string{
+			"description": "This alert is fired when the defined metric (current value: {{$value}}) crosses the threshold ({{$threshold}})",
+			"summary":     "The rule threshold is set to {{$threshold}}, and the observed metric value is {{$value}}",
+		}
+
+		options := clickhouseReader.NewOptions("", 0, 0, 0, "", "archiveNamespace")
+		reader := clickhouseReader.NewReaderFromClickhouseConnection(mock, options, nil, "", fm, "")
+
+		rule, err := NewThresholdRule("69", &postableRule, ThresholdRuleOpts{}, fm, reader)
+		rule.temporalityMap = map[string]map[v3.Temporality]bool{
+			"signoz_calls_total": {
+				v3.Delta: true,
+			},
+		}
+		if err != nil {
+			assert.NoError(t, err)
+		}
+
+		queriers := Queriers{
+			Ch: mock,
+		}
+
+		retVal, err := rule.Eval(context.Background(), time.Now(), &queriers)
+		if err != nil {
+			assert.NoError(t, err)
+		}
+
+		assert.Equal(t, 1, retVal.(int), "case %d", idx)
+		for _, item := range rule.active {
+			if c.expectNoData {
+				assert.True(t, strings.Contains(item.Labels.Get(labels.AlertNameLabel), "[No data]"), "case %d", idx)
+			} else {
+				assert.False(t, strings.Contains(item.Labels.Get(labels.AlertNameLabel), "[No data]"), "case %d", idx)
+			}
+		}
+	}
+}

pkg/query-service/utils/labels/labels.go

@@ -27,8 +27,6 @@ const (
 	RuleThresholdLabel    = "threshold"
 	AlertSummaryLabel     = "summary"
 	AlertDescriptionLabel = "description"
-
-	AlertMissingData = "Missing data"
 )
 
 // Label is a key/value pair of strings.