feat: Support slack channel passed as config in notification API (#86)

* feat: Support slack channel passed as config in notification API

* fix: use any instead of using interface{} for RecieverSelectors

* fix: refacotor method name error handling

* fix: simplify code

* fix: post notification override

---------

Co-authored-by: Muhammad Abduh <mabdh@users.noreply.github.com>

core/notification/notification.go

@@ -36,16 +36,16 @@ type Transactor interface {
 
 // Notification is a model of notification
 type Notification struct {
-	ID                string              `json:"id"`
-	NamespaceID       uint64              `json:"namespace_id"`
-	Type              string              `json:"type"`
-	Data              map[string]any      `json:"data"`
-	Labels            map[string]string   `json:"labels"`
-	ValidDuration     time.Duration       `json:"valid_duration"`
-	Template          string              `json:"template"`
-	UniqueKey         string              `json:"unique_key"`
-	ReceiverSelectors []map[string]string `json:"receiver_selectors"`
-	CreatedAt         time.Time           `json:"created_at"`
+	ID                string            `json:"id"`
+	NamespaceID       uint64            `json:"namespace_id"`
+	Type              string            `json:"type"`
+	Data              map[string]any    `json:"data"`
+	Labels            map[string]string `json:"labels"`
+	ValidDuration     time.Duration     `json:"valid_duration"`
+	Template          string            `json:"template"`
+	UniqueKey         string            `json:"unique_key"`
+	ReceiverSelectors ReceiverSelectors `json:"receiver_selectors"`
+	CreatedAt         time.Time         `json:"created_at"`
 
 	// won't be stored in notification table, only to propagate this to notification_subscriber
 	AlertIDs []int64

core/notification/notification_test.go

@@ -41,7 +41,7 @@ func TestNotification_Validate(t *testing.T) {
 				Labels: map[string]string{
 					"receiver_id": "2",
 				},
-				ReceiverSelectors: []map[string]string{
+				ReceiverSelectors: []map[string]any{
 					{
 						"varkey1": "value1",
 					},

core/notification/receiver_selectors.go

@@ -0,0 +1,42 @@
+package notification
+
+import (
+	"github.com/goto/siren/pkg/errors"
+)
+
+type ReceiverSelectors []map[string]any
+
+func (rs ReceiverSelectors) parseAndValidate() ([]map[string]string, map[string]any, error) {
+	// Check if any selector contains a config
+	var selectorConfig map[string]any
+	for i := 0; i < len(rs); i++ {
+		selector := rs[i]
+		if v, cok := selector["config"]; cok {
+			if m, ok := v.(map[string]any); ok {
+				selectorConfig = m
+				delete(rs[i], "config")
+			} else {
+				return nil, nil, errors.ErrInvalid.WithMsgf("config should be in map and follow notification config")
+			}
+			break
+		}
+	}
+
+	if selectorConfig != nil && len(rs) > 1 {
+		return nil, nil, errors.ErrInvalid.WithMsgf("config override could only be used with one selector")
+	}
+
+	castedSelectors := make([]map[string]string, len(rs))
+	for i, selector := range rs {
+		castedSelectors[i] = make(map[string]string)
+		for k, v := range selector {
+			if str, ok := v.(string); ok {
+				castedSelectors[i][k] = str
+			} else {
+				return nil, nil, errors.ErrInvalid.WithMsgf("receiver selector value of '%s' should be a string", k)
+			}
+		}
+	}
+
+	return castedSelectors, selectorConfig, nil
+}

core/notification/router_receiver_service.go

@@ -26,8 +26,13 @@ func (s *RouterReceiverService) PrepareMetaMessages(ctx context.Context, n Notif
 		return nil, nil, errors.ErrInvalid.WithMsgf("number of receiver selectors should be less than or equal threshold %d", s.deps.Cfg.MaxNumReceiverSelectors)
 	}
 
+	selectors, selectorConfig, err := n.ReceiverSelectors.parseAndValidate()
+	if err != nil {
+		return nil, nil, err
+	}
+
 	rcvs, err := s.deps.ReceiverService.List(ctx, receiver.Filter{
-		MultipleLabels: n.ReceiverSelectors,
+		MultipleLabels: selectors,
 		Expanded:       true,
 	})
 	if err != nil {
@@ -38,6 +43,24 @@ func (s *RouterReceiverService) PrepareMetaMessages(ctx context.Context, n Notif
 		return nil, nil, errors.ErrNotFound
 	}
 
+	if selectorConfig != nil && len(rcvs) > 1 {
+		return nil, nil, errors.ErrInvalid.WithMsgf("config override could only be used to 1 receiver, but got %d receiver", len(rcvs))
+	} else if selectorConfig != nil && len(rcvs) == 1 {
+		// config override flow
+		var rcvView = &subscription.ReceiverView{}
+		rcvView.FromReceiver(rcvs[0])
+		rcvView.Configurations = s.mergeReceiverConfig(rcvView.Configurations, selectorConfig)
+		metaMessages = append(metaMessages, n.MetaMessage(*rcvView))
+
+		notificationLogs = append(notificationLogs, log.Notification{
+			NamespaceID:    n.NamespaceID,
+			NotificationID: n.ID,
+			ReceiverID:     rcvs[0].ID,
+			AlertIDs:       n.AlertIDs,
+		})
+		return metaMessages, notificationLogs, nil
+	}
+
 	for _, rcv := range rcvs {
 		var rcvView = &subscription.ReceiverView{}
 		rcvView.FromReceiver(rcv)
@@ -58,3 +81,15 @@ func (s *RouterReceiverService) PrepareMetaMessages(ctx context.Context, n Notif
 
 	return metaMessages, notificationLogs, nil
 }
+
+func (s *RouterReceiverService) mergeReceiverConfig(receiverConfig, selectorConfig map[string]any) map[string]any {
+	// override the existing config with the one from API if there is config clash
+	result := map[string]any{}
+	for k, v := range receiverConfig {
+		result[k] = v
+	}
+	for k, v := range selectorConfig {
+		result[k] = v
+	}
+	return result
+}