Add comments about AWS S3

attachment/store.go

@@ -157,7 +157,7 @@ func (c *Store) sync() error {
 	// than the grace period to account for races, and skipping objects with invalid IDs.
 	cutoff := time.Now().Add(-orphanGracePeriod)
 	var orphanIDs []string
-	var size int64
+	var count, size int64
 	sizes := make(map[string]int64, len(remoteObjects))
 	for _, obj := range remoteObjects {
 		if !fileIDRegex.MatchString(obj.ID) {
@@ -166,11 +166,12 @@ func (c *Store) sync() error {
 		if _, ok := localIDMap[obj.ID]; !ok && obj.LastModified.Before(cutoff) {
 			orphanIDs = append(orphanIDs, obj.ID)
 		} else {
+			count++
 			size += obj.Size
 			sizes[obj.ID] = obj.Size
 		}
 	}
-	log.Tag(tagStore).Debug("Attachment store updated: %d attachment(s), %s", len(localIDs), util.FormatSizeHuman(size))
+	log.Tag(tagStore).Debug("Attachment store updated: %d attachment(s), %s", count, util.FormatSizeHuman(size))
 	c.mu.Lock()
 	c.size = size
 	c.sizes = sizes

docs/config.md

@@ -565,6 +565,34 @@ When `endpoint` is specified, path-style addressing is enabled automatically (us
 Note that the access key and secret key may have to be URL encoded. For instance, a secret key `YmxhY+mxhYmxhC` (note the `+`) should
 be encoded as `YmxhY%2BmxhYmxhC` (note the `%2B`), so the URL would be `s3://ACCESS_KEY:YmxhY%2BmxhYmxhC@my-bucket/attachments...`.
 
+For **AWS S3**, the IAM user needs the following permissions on the bucket:
+
+``` json
+{
+    "Version": "2012-10-17",
+    "Statement": [
+        {
+            "Effect": "Allow",
+            "Action": [
+                "s3:ListBucket",
+                "s3:ListBucketMultipartUploads"
+            ],
+            "Resource": "arn:aws:s3:::BUCKET_NAME"
+        },
+        {
+            "Effect": "Allow",
+            "Action": [
+                "s3:GetObject",
+                "s3:PutObject",
+                "s3:DeleteObject",
+                "s3:AbortMultipartUpload"
+            ],
+            "Resource": "arn:aws:s3:::BUCKET_NAME/*"
+        }
+    ]
+}
+```
+
 ## Access control
 By default, the ntfy server is open for everyone, meaning **everyone can read and write to any topic** (this is how
 ntfy.sh is configured). To restrict access to your own server, you can optionally configure authentication and authorization. 

docs/releases.md

@@ -1802,7 +1802,7 @@ and the [ntfy Android app](https://github.com/binwiederhier/ntfy-android/release
 
 **Features:**
 
-* Add S3-compatible object storage as an alternative [attachment](config.md#attachments) backend via `attachment-cache-dir` config option
+* Add S3-compatible object storage as an alternative [attachment store](config.md#attachments) via `attachment-cache-dir` config option
 
 **Bug fixes + maintenance:**
 

s3/client.go

@@ -25,6 +25,32 @@ const (
 // and ListObjectsV2 operations using AWS Signature V4 signing. The bucket and optional key prefix
 // are fixed at construction time. All operations target the same bucket and prefix.
 //
+// The following IAM policy is required for AWS S3:
+//
+//	{
+//	    "Version": "2012-10-17",
+//	    "Statement": [
+//	        {
+//	            "Effect": "Allow",
+//	            "Action": [
+//	                "s3:ListBucket",
+//	                "s3:ListBucketMultipartUploads"
+//	            ],
+//	            "Resource": "arn:aws:s3:::BUCKET_NAME"
+//	        },
+//	        {
+//	            "Effect": "Allow",
+//	            "Action": [
+//	                "s3:GetObject",
+//	                "s3:PutObject",
+//	                "s3:DeleteObject",
+//	                "s3:AbortMultipartUpload"
+//	            ],
+//	            "Resource": "arn:aws:s3:::BUCKET_NAME/*"
+//	        }
+//	    ]
+//	}
+//
 // Fields must not be modified after the Client is passed to any method or goroutine.
 type Client struct {
 	config *Config
@@ -149,7 +175,11 @@ func (c *Client) ListObjectsV2(ctx context.Context) ([]*Object, error) {
 
 // listObjectsV2 performs a single ListObjectsV2 request using the client's configured prefix.
 func (c *Client) listObjectsV2(ctx context.Context, continuationToken string) (*listObjectsV2Result, error) {
-	log.Tag(tagS3Client).Debug("Listing remote objects with continuation token '%s'", continuationToken)
+	if continuationToken == "" {
+		log.Tag(tagS3Client).Debug("Listing remote objects")
+	} else {
+		log.Tag(tagS3Client).Debug("Listing remote objects, continuing with token '%s'", continuationToken)
+	}
 	query := url.Values{"list-type": {"2"}}
 	if prefix := c.config.ListPrefix(); prefix != "" {
 		query.Set("prefix", prefix)