feat: support printing threshold in alert summary and description (#1827)

frontend/src/container/CreateAlertRule/defaults.ts

@@ -6,6 +6,16 @@ import {
 	defaultMatchType,
 } from 'types/api/alerts/def';
 
+const defaultAlertDescription =
+	'This alert is fired when the defined metric (current value: {{$value}}) crosses the threshold ({{$threshold}})';
+const defaultAlertSummary =
+	'The rule threshold is set to {{$threshold}}, and the observed metric value is {{$value}}';
+
+const defaultAnnotations = {
+	description: defaultAlertDescription,
+	summary: defaultAlertSummary,
+};
+
 export const alertDefaults: AlertDef = {
 	alertType: AlertTypes.METRICS_BASED_ALERT,
 	condition: {
@@ -38,9 +48,7 @@ export const alertDefaults: AlertDef = {
 	labels: {
 		severity: 'warning',
 	},
-	annotations: {
-		description: 'A new alert',
-	},
+	annotations: defaultAnnotations,
 	evalWindow: defaultEvalWindow,
 };
 
@@ -85,9 +93,7 @@ export const logAlertDefaults: AlertDef = {
 		severity: 'warning',
 		details: `${window.location.protocol}//${window.location.host}/logs`,
 	},
-	annotations: {
-		description: 'A new log-based alert',
-	},
+	annotations: defaultAnnotations,
 	evalWindow: defaultEvalWindow,
 };
 
@@ -132,9 +138,7 @@ export const traceAlertDefaults: AlertDef = {
 		severity: 'warning',
 		details: `${window.location.protocol}//${window.location.host}/traces`,
 	},
-	annotations: {
-		description: 'A new trace-based alert',
-	},
+	annotations: defaultAnnotations,
 	evalWindow: defaultEvalWindow,
 };
 
@@ -179,8 +183,6 @@ export const exceptionAlertDefaults: AlertDef = {
 		severity: 'warning',
 		details: `${window.location.protocol}//${window.location.host}/exceptions`,
 	},
-	annotations: {
-		description: 'A new exceptions-based alert',
-	},
+	annotations: defaultAnnotations,
 	evalWindow: defaultEvalWindow,
 };

pkg/query-service/rules/apiParams.go

@@ -197,8 +197,8 @@ func testTemplateParsing(rl *PostableRule) (errs []error) {
 	}
 
 	// Trying to parse templates.
-	tmplData := AlertTemplateData(make(map[string]string), 0)
-	defs := "{{$labels := .Labels}}{{$value := .Value}}"
+	tmplData := AlertTemplateData(make(map[string]string), 0, 0)
+	defs := "{{$labels := .Labels}}{{$value := .Value}}{{$threshold := .Threshold}}"
 	parseTest := func(text string) error {
 		tmpl := NewTemplateExpander(
 			context.TODO(),

pkg/query-service/rules/promRule.go

@@ -108,6 +108,14 @@ func (r *PromRule) Condition() *RuleCondition {
 	return r.ruleCondition
 }
 
+func (r *PromRule) targetVal() float64 {
+	if r.ruleCondition == nil || r.ruleCondition.Target == nil {
+		return 0
+	}
+
+	return *r.ruleCondition.Target
+}
+
 func (r *PromRule) Type() RuleType {
 	return RuleTypeProm
 }
@@ -327,10 +335,10 @@ func (r *PromRule) Eval(ctx context.Context, ts time.Time, queriers *Queriers) (
 			l[lbl.Name] = lbl.Value
 		}
 
-		tmplData := AlertTemplateData(l, smpl.V)
+		tmplData := AlertTemplateData(l, smpl.V, r.targetVal())
 		// Inject some convenience variables that are easier to remember for users
 		// who are not used to Go's templating system.
-		defs := "{{$labels := .Labels}}{{$value := .Value}}"
+		defs := "{{$labels := .Labels}}{{$value := .Value}}{{$threshold := .Threshold}}"
 
 		expand := func(text string) string {
 

pkg/query-service/rules/templates.go

@@ -21,8 +21,9 @@ import (
 // related to go templating in rule labels and annotations
 
 type tmplQueryRecord struct {
-	Labels map[string]string
-	Value  float64
+	Labels    map[string]string
+	Value     float64
+	Threshold float64
 }
 type tmplQueryResults []*tmplQueryRecord
 
@@ -200,13 +201,15 @@ func NewTemplateExpander(
 }
 
 // AlertTemplateData returns the interface to be used in expanding the template.
-func AlertTemplateData(labels map[string]string, value float64) interface{} {
+func AlertTemplateData(labels map[string]string, value float64, threshold float64) interface{} {
 	return struct {
-		Labels map[string]string
-		Value  float64
+		Labels    map[string]string
+		Value     float64
+		Threshold float64
 	}{
-		Labels: labels,
-		Value:  value,
+		Labels:    labels,
+		Value:     value,
+		Threshold: threshold,
 	}
 }
 

pkg/query-service/rules/thresholdRule.go

@@ -673,10 +673,10 @@ func (r *ThresholdRule) Eval(ctx context.Context, ts time.Time, queriers *Querie
 			l[lbl.Name] = lbl.Value
 		}
 
-		tmplData := AlertTemplateData(l, smpl.V)
+		tmplData := AlertTemplateData(l, smpl.V, r.targetVal())
 		// Inject some convenience variables that are easier to remember for users
 		// who are not used to Go's templating system.
-		defs := "{{$labels := .Labels}}{{$value := .Value}}"
+		defs := "{{$labels := .Labels}}{{$value := .Value}}{{$threshold := .Threshold}}"
 
 		// utility function to apply go template on labels and annots
 		expand := func(text string) string {