1

internal/config/config.go

@@ -24,6 +24,8 @@ type Config struct {
 	AWSRegion      string
 	S3UploadPrefix string
 	S3PublicBase   string // optional CDN / website endpoint base URL for returned object URLs
+	// S3ObjectACL: optional canned ACL on PutObject (e.g. public-read). Empty = omit ACL (required for Bucket owner enforced buckets).
+	S3ObjectACL string
 }
 
 func Load() Config {
@@ -74,6 +76,7 @@ func Load() Config {
 	}
 	s3Prefix = strings.Trim(s3Prefix, "/")
 	s3Public := strings.TrimSpace(os.Getenv("S3_PUBLIC_BASE_URL"))
+	s3ObjectACL := strings.TrimSpace(os.Getenv("S3_OBJECT_ACL"))
 	return Config{
 		Addr:                addr,
 		DatabaseURL:         db,
@@ -89,6 +92,7 @@ func Load() Config {
 		AWSRegion:           awsRegion,
 		S3UploadPrefix:      s3Prefix,
 		S3PublicBase:        s3Public,
+		S3ObjectACL:         s3ObjectACL,
 	}
 }
 

internal/handlers/upload.go

@@ -11,6 +11,7 @@ import (
 
 	"github.com/aws/aws-sdk-go-v2/aws"
 	"github.com/aws/aws-sdk-go-v2/service/s3"
+	"github.com/aws/aws-sdk-go-v2/service/s3/types"
 	"github.com/google/uuid"
 )
 
@@ -25,6 +26,7 @@ type UploadDeps struct {
 	AWSRegion       string
 	S3Prefix        string // e.g. "uploads" (no leading/trailing slashes)
 	S3PublicBase    string // optional, e.g. https://cdn.example.com — else virtual-hosted S3 URL
+	S3ObjectACL     string // optional canned ACL, e.g. public-read (bucket must allow ACLs)
 }
 
 func UploadFile(d UploadDeps) http.HandlerFunc {
@@ -71,12 +73,16 @@ func UploadFile(d UploadDeps) http.HandlerFunc {
 			}
 			key := pfx + "/" + name
 			ctx := r.Context()
-			_, err := d.S3.PutObject(ctx, &s3.PutObjectInput{
+			put := &s3.PutObjectInput{
 				Bucket:      aws.String(d.S3Bucket),
 				Key:         aws.String(key),
 				Body:        bytes.NewReader(data),
 				ContentType: aws.String(ct),
-			})
+			}
+			if acl, ok := s3PutObjectCannedACL(d.S3ObjectACL); ok {
+				put.ACL = acl
+			}
+			_, err := d.S3.PutObject(ctx, put)
 			if err != nil {
 				http.Error(w, err.Error(), http.StatusInternalServerError)
 				return
@@ -105,6 +111,28 @@ func UploadFile(d UploadDeps) http.HandlerFunc {
 	}
 }
 
+// s3PutObjectCannedACL maps env S3_OBJECT_ACL to SDK enum; unknown values are ignored.
+func s3PutObjectCannedACL(raw string) (types.ObjectCannedACL, bool) {
+	switch strings.TrimSpace(strings.ToLower(raw)) {
+	case "private":
+		return types.ObjectCannedACLPrivate, true
+	case "public-read":
+		return types.ObjectCannedACLPublicRead, true
+	case "public-read-write":
+		return types.ObjectCannedACLPublicReadWrite, true
+	case "authenticated-read":
+		return types.ObjectCannedACLAuthenticatedRead, true
+	case "bucket-owner-full-control":
+		return types.ObjectCannedACLBucketOwnerFullControl, true
+	case "bucket-owner-read":
+		return types.ObjectCannedACLBucketOwnerRead, true
+	case "aws-exec-read":
+		return types.ObjectCannedACLAwsExecRead, true
+	default:
+		return "", false
+	}
+}
+
 func publicObjectURL(base, bucket, region, key string) string {
 	base = strings.TrimSpace(base)
 	if base != "" {