alerting rules default to sort by update time

Signed-off-by: junotx <junotx@126.com>

pkg/models/alerting/alerting.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"sort"
 	"strings"
+	"time"
 
 	"github.com/pkg/errors"
 	promresourcesv1 "github.com/prometheus-operator/prometheus-operator/pkg/apis/monitoring/v1"
@@ -470,6 +471,8 @@ func (o *operator) CreateCustomAlertingRule(ctx context.Context, namespace strin
 		return v2alpha1.ErrAlertingRuleAlreadyExists
 	}
 
+	setRuleUpdateTime(rule, time.Now())
+
 	return ruler.AddAlertingRule(ctx, ruleNamespace, extraRuleResourceSelector,
 		customRuleGroupDefault, parseToPrometheusRule(rule), ruleResourceLabels)
 }
@@ -521,6 +524,8 @@ func (o *operator) UpdateCustomAlertingRule(ctx context.Context, namespace, name
 		return v2alpha1.ErrAlertingRuleNotFound
 	}
 
+	setRuleUpdateTime(rule, time.Now())
+
 	return ruler.UpdateAlertingRule(ctx, ruleNamespace, extraRuleResourceSelector,
 		resourceRule.Group, parseToPrometheusRule(rule), ruleResourceLabels)
 }
@@ -633,3 +638,13 @@ func pageAlerts(alertingRules []*v2alpha1.GettableAlertingRule,
 		Items: queryParams.Sub(alerts),
 	}
 }
+
+func setRuleUpdateTime(rule *v2alpha1.PostableAlertingRule, t time.Time) {
+	if rule.Annotations == nil {
+		rule.Annotations = make(map[string]string)
+	}
+	if t.IsZero() {
+		t = time.Now()
+	}
+	rule.Annotations[v2alpha1.AnnotationKeyRuleUpdateTime] = t.UTC().Format(time.RFC3339)
+}