Alerting: introduce AlertRuleGroupKey and use it in API handlers (#48945)

* create AlertGroupKey structure
* update PrometheusSrv.
  - extract creation of RuleGroup to a separate method. Use group key for grouping
* update RuleSrv 
 - update calculateChanges to use groupKey
 - authorize to use groupkey

pkg/services/ngalert/models/alert_rule.go

@@ -167,6 +167,17 @@ type AlertRuleKey struct {
 	UID   string
 }
 
+// AlertRuleGroupKey is the identifier of a group of alerts
+type AlertRuleGroupKey struct {
+	OrgID        int64
+	NamespaceUID string
+	RuleGroup    string
+}
+
+func (k AlertRuleGroupKey) String() string {
+	return fmt.Sprintf("{orgID: %d, namespaceUID: %s, groupName: %s}", k.OrgID, k.NamespaceUID, k.RuleGroup)
+}
+
 func (k AlertRuleKey) String() string {
 	return fmt.Sprintf("{orgID: %d, UID: %s}", k.OrgID, k.UID)
 }
@@ -176,6 +187,11 @@ func (alertRule *AlertRule) GetKey() AlertRuleKey {
 	return AlertRuleKey{OrgID: alertRule.OrgID, UID: alertRule.UID}
 }
 
+// GetGroupKey returns the identifier of a group the rule belongs to
+func (alertRule *AlertRule) GetGroupKey() AlertRuleGroupKey {
+	return AlertRuleGroupKey{OrgID: alertRule.OrgID, NamespaceUID: alertRule.NamespaceUID, RuleGroup: alertRule.RuleGroup}
+}
+
 // GetKey returns the alert definitions identifier
 func (alertRule *SchedulableAlertRule) GetKey() AlertRuleKey {
 	return AlertRuleKey{OrgID: alertRule.OrgID, UID: alertRule.UID}

pkg/services/ngalert/models/testing.go

@@ -133,6 +133,15 @@ func GenerateAlertRules(count int, f func() *AlertRule) []*AlertRule {
 	return result
 }
 
+// GenerateGroupKey generates many random alert rules. Does not guarantee that rules are unique (by UID)
+func GenerateGroupKey(orgID int64) AlertRuleGroupKey {
+	return AlertRuleGroupKey{
+		OrgID:        orgID,
+		NamespaceUID: util.GenerateShortUID(),
+		RuleGroup:    util.GenerateShortUID(),
+	}
+}
+
 // CopyRule creates a deep copy of AlertRule
 func CopyRule(r *AlertRule) *AlertRule {
 	result := AlertRule{