Alerting: Store instance annotations in alert rule state (#114975)

Alerting: Store annotations in alert instance state

pkg/services/ngalert/models/instance_annotations.go

@@ -0,0 +1,34 @@
+package models
+
+import (
+	"encoding/json"
+)
+
+// InstanceAnnotations is an extension to map[string]string with methods
+// for database serialization.
+type InstanceAnnotations map[string]string
+
+// FromDB loads annotations stored in the database as JSON into InstanceAnnotations.
+// FromDB is part of the xorm Conversion interface.
+func (a *InstanceAnnotations) FromDB(b []byte) error {
+	if len(b) == 0 {
+		*a = nil
+		return nil
+	}
+	annotations := make(map[string]string)
+	err := json.Unmarshal(b, &annotations)
+	if err != nil {
+		return err
+	}
+	*a = annotations
+	return nil
+}
+
+// ToDB serializes InstanceAnnotations to JSON for database storage.
+// ToDB is part of the xorm Conversion interface.
+func (a *InstanceAnnotations) ToDB() ([]byte, error) {
+	if a == nil || len(*a) == 0 {
+		return nil, nil
+	}
+	return json.Marshal(*a)
+}