feat: Set up bucket event notifications with nats

s3event/event.go

@@ -14,7 +14,11 @@
 
 package s3event
 
-import "github.com/gofiber/fiber/v2"
+import (
+	"fmt"
+
+	"github.com/gofiber/fiber/v2"
+)
 
 type S3EventSender interface {
 	SendEvent(ctx *fiber.Ctx, meta EventMeta)
@@ -108,9 +112,17 @@ type EventConfig struct {
 	KafkaURL      string
 	KafkaTopic    string
 	KafkaTopicKey string
+	NatsURL       string
+	NatsTopic     string
 }
 
 func InitEventSender(cfg *EventConfig) (S3EventSender, error) {
+	if cfg.KafkaURL != "" && cfg.NatsURL != "" {
+		return nil, fmt.Errorf("there should be specified one of the following: kafka, nats")
+	}
+	if cfg.NatsURL != "" {
+		return InitNatsNotifSender(cfg.NatsURL, cfg.NatsTopic)
+	}
 	if cfg.KafkaURL != "" {
 		return InitKafkaEventService(cfg.KafkaURL, cfg.KafkaTopic, cfg.KafkaTopicKey)
 	}

s3event/nats.go

@@ -0,0 +1,113 @@
+// Copyright 2023 Versity Software
+// This file is licensed under the Apache License, Version 2.0
+// (the "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package s3event
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/gofiber/fiber/v2"
+	"github.com/nats-io/nats.go"
+)
+
+type NatsEventSender struct {
+	EventFields
+	topic  string
+	client *nats.Conn
+	mu     sync.Mutex
+}
+
+func InitNatsNotifSender(url, topic string) (S3EventSender, error) {
+	if topic == "" {
+		return nil, fmt.Errorf("nats message topic should be specified")
+	}
+
+	client, err := nats.Connect(url)
+	if err != nil {
+		return nil, err
+	}
+
+	return &NatsEventSender{
+		topic:  topic,
+		client: client,
+	}, nil
+}
+
+func (ns *NatsEventSender) SendEvent(ctx *fiber.Ctx, meta EventMeta) {
+	ns.mu.Lock()
+	defer ns.mu.Unlock()
+
+	path := strings.Split(ctx.Path(), "/")
+	bucket, object := path[1], strings.Join(path[2:], "/")
+
+	schema := EventSchema{
+		EventVersion: "2.2",
+		EventSource:  "aws:s3",
+		AwsRegion:    ctx.Locals("region").(string),
+		EventTime:    time.Now().Format(time.RFC3339),
+		EventName:    meta.EventName,
+		UserIdentity: EventUserIdentity{
+			PrincipalId: ctx.Locals("access").(string),
+		},
+		RequestParameters: EventRequestParams{
+			SourceIPAddress: ctx.IP(),
+		},
+		ResponseElements: EventResponseElements{
+			RequestId: ctx.Get("X-Amz-Request-Id"),
+			HostId:    ctx.Get("X-Amx-Id-2"),
+		},
+		S3: EventS3Data{
+			S3SchemaVersion: "1.0",
+			// This field will come up after implementing per bucket notifications
+			ConfigurationId: "nats-global",
+			Bucket: EventS3BucketData{
+				Name: bucket,
+				OwnerIdentity: EventUserIdentity{
+					PrincipalId: ctx.Locals("access").(string),
+				},
+				Arn: fmt.Sprintf("arn:aws:s3:::%v", strings.Join(path, "/")),
+			},
+			Object: EventObjectData{
+				Key:       object,
+				Size:      meta.ObjectSize,
+				ETag:      meta.ObjectETag,
+				VersionId: meta.VersionId,
+				Sequencer: genSequencer(),
+			},
+		},
+		GlacierEventData: EventGlacierData{
+			// Not supported
+			RestoreEventData: EventRestoreData{},
+		},
+	}
+
+	ns.Records = []EventSchema{schema}
+	ns.sendEvent()
+}
+
+func (ns *NatsEventSender) sendEvent() {
+	jsonEvent, err := json.Marshal(ns)
+	if err != nil {
+		fmt.Printf("\n failed to parse the event data: %v", err.Error())
+	}
+
+	err = ns.client.Publish(ns.topic, jsonEvent)
+	if err != nil {
+		fmt.Println("failed to send nats event: ", err.Error())
+	}
+}