app/encrypted_storage.py

@@ -266,5 +266,11 @@ class EncryptedObjectStorage:
     def list_multipart_parts(self, bucket_name: str, upload_id: str):
         return self.storage.list_multipart_parts(bucket_name, upload_id)
     
+    def get_bucket_quota(self, bucket_name: str):
+        return self.storage.get_bucket_quota(bucket_name)
+    
+    def set_bucket_quota(self, bucket_name: str, *, max_bytes=None, max_objects=None):
+        return self.storage.set_bucket_quota(bucket_name, max_bytes=max_bytes, max_objects=max_objects)
+    
     def _compute_etag(self, path: Path) -> str:
         return self.storage._compute_etag(path)

app/errors.py

@@ -129,6 +129,25 @@ class EntityTooLargeError(AppError):
     status_code: int = 413
 
 
+@dataclass
+class QuotaExceededAppError(AppError):
+    """Bucket quota exceeded."""
+    code: str = "QuotaExceeded"
+    message: str = "The bucket quota has been exceeded"
+    status_code: int = 403
+    quota: Optional[Dict[str, Any]] = None
+    usage: Optional[Dict[str, int]] = None
+    
+    def __post_init__(self):
+        if self.quota or self.usage:
+            self.details = {}
+            if self.quota:
+                self.details["quota"] = self.quota
+            if self.usage:
+                self.details["usage"] = self.usage
+        super().__post_init__()
+
+
 def handle_app_error(error: AppError) -> Response:
     """Handle application errors with appropriate response format."""
     log_extra = {"error_code": error.code}
@@ -163,5 +182,6 @@ def register_error_handlers(app):
         ObjectNotFoundError, InvalidObjectKeyError,
         AccessDeniedError, InvalidCredentialsError,
         MalformedRequestError, InvalidArgumentError, EntityTooLargeError,
+        QuotaExceededAppError,
     ]:
         app.register_error_handler(error_class, handle_app_error)

app/s3_api.py

@@ -18,7 +18,7 @@ from .bucket_policies import BucketPolicyStore
 from .extensions import limiter
 from .iam import IamError, Principal
 from .replication import ReplicationManager
-from .storage import ObjectStorage, StorageError
+from .storage import ObjectStorage, StorageError, QuotaExceededError
 
 s3_api_bp = Blueprint("s3_api", __name__)
 
@@ -803,6 +803,7 @@ def _maybe_handle_bucket_subresource(bucket_name: str) -> Response | None:
         "acl": _bucket_acl_handler,
         "versions": _bucket_list_versions_handler,
         "lifecycle": _bucket_lifecycle_handler,
+        "quota": _bucket_quota_handler,
     }
     requested = [key for key in handlers if key in request.args]
     if not requested:
@@ -1400,6 +1401,87 @@ def _parse_lifecycle_config(payload: bytes) -> list:
     return rules
 
 
+def _bucket_quota_handler(bucket_name: str) -> Response:
+    """Handle bucket quota configuration (GET/PUT/DELETE /<bucket>?quota)."""
+    if request.method not in {"GET", "PUT", "DELETE"}:
+        return _method_not_allowed(["GET", "PUT", "DELETE"])
+    
+    principal, error = _require_principal()
+    if error:
+        return error
+    try:
+        _authorize_action(principal, bucket_name, "policy")
+    except IamError as exc:
+        return _error_response("AccessDenied", str(exc), 403)
+    
+    storage = _storage()
+    
+    if not storage.bucket_exists(bucket_name):
+        return _error_response("NoSuchBucket", "Bucket does not exist", 404)
+    
+    if request.method == "GET":
+        quota = storage.get_bucket_quota(bucket_name)
+        if not quota:
+            return _error_response("NoSuchQuotaConfiguration", "No quota configuration found", 404)
+        
+        # Return as JSON for simplicity (not a standard S3 API)
+        stats = storage.bucket_stats(bucket_name)
+        return jsonify({
+            "quota": quota,
+            "usage": {
+                "bytes": stats.get("bytes", 0),
+                "objects": stats.get("objects", 0),
+            }
+        })
+    
+    if request.method == "DELETE":
+        try:
+            storage.set_bucket_quota(bucket_name, max_size_bytes=None, max_objects=None)
+        except StorageError as exc:
+            return _error_response("NoSuchBucket", str(exc), 404)
+        current_app.logger.info("Bucket quota deleted", extra={"bucket": bucket_name})
+        return Response(status=204)
+    
+    # PUT
+    payload = request.get_json(silent=True)
+    if not payload:
+        return _error_response("MalformedRequest", "Request body must be JSON with quota limits", 400)
+    
+    max_size_bytes = payload.get("max_size_bytes")
+    max_objects = payload.get("max_objects")
+    
+    if max_size_bytes is None and max_objects is None:
+        return _error_response("InvalidArgument", "At least one of max_size_bytes or max_objects is required", 400)
+    
+    # Validate types
+    if max_size_bytes is not None:
+        try:
+            max_size_bytes = int(max_size_bytes)
+            if max_size_bytes < 0:
+                raise ValueError("must be non-negative")
+        except (TypeError, ValueError) as exc:
+            return _error_response("InvalidArgument", f"max_size_bytes {exc}", 400)
+    
+    if max_objects is not None:
+        try:
+            max_objects = int(max_objects)
+            if max_objects < 0:
+                raise ValueError("must be non-negative")
+        except (TypeError, ValueError) as exc:
+            return _error_response("InvalidArgument", f"max_objects {exc}", 400)
+    
+    try:
+        storage.set_bucket_quota(bucket_name, max_size_bytes=max_size_bytes, max_objects=max_objects)
+    except StorageError as exc:
+        return _error_response("NoSuchBucket", str(exc), 404)
+    
+    current_app.logger.info(
+        "Bucket quota updated",
+        extra={"bucket": bucket_name, "max_size_bytes": max_size_bytes, "max_objects": max_objects}
+    )
+    return Response(status=204)
+
+
 def _bulk_delete_handler(bucket_name: str) -> Response:
     principal, error = _require_principal()
     if error:
@@ -1749,6 +1831,8 @@ def object_handler(bucket_name: str, object_key: str):
                 stream,
                 metadata=metadata or None,
             )
+        except QuotaExceededError as exc:
+            return _error_response("QuotaExceeded", str(exc), 403)
         except StorageError as exc:
             message = str(exc)
             if "Bucket" in message:
@@ -2256,6 +2340,8 @@ def _complete_multipart_upload(bucket_name: str, object_key: str) -> Response:
 
     try:
         meta = _storage().complete_multipart_upload(bucket_name, upload_id, parts)
+    except QuotaExceededError as exc:
+        return _error_response("QuotaExceeded", str(exc), 403)
     except StorageError as exc:
         if "NoSuchBucket" in str(exc):
             return _error_response("NoSuchBucket", str(exc), 404)

app/storage.py

@@ -75,6 +75,15 @@ class StorageError(RuntimeError):
     """Raised when the storage layer encounters an unrecoverable problem."""
 
 
+class QuotaExceededError(StorageError):
+    """Raised when an operation would exceed bucket quota limits."""
+    
+    def __init__(self, message: str, quota: Dict[str, Any], usage: Dict[str, int]):
+        super().__init__(message)
+        self.quota = quota
+        self.usage = usage
+
+
 @dataclass
 class ObjectMeta:
     key: str
@@ -169,16 +178,38 @@ class ObjectStorage:
 
         object_count = 0
         total_bytes = 0
+        version_count = 0
+        version_bytes = 0
+        
+        # Count current objects in the bucket folder
         for path in bucket_path.rglob("*"):
             if path.is_file():
                 rel = path.relative_to(bucket_path)
-                if rel.parts and rel.parts[0] in self.INTERNAL_FOLDERS:
+                if not rel.parts:
                     continue
+                top_folder = rel.parts[0]
+                if top_folder not in self.INTERNAL_FOLDERS:
                     stat = path.stat()
                     object_count += 1
                     total_bytes += stat.st_size
         
-        stats = {"objects": object_count, "bytes": total_bytes}
+        # Count archived versions in the system folder
+        versions_root = self._bucket_versions_root(bucket_name)
+        if versions_root.exists():
+            for path in versions_root.rglob("*.bin"):
+                if path.is_file():
+                    stat = path.stat()
+                    version_count += 1
+                    version_bytes += stat.st_size
+        
+        stats = {
+            "objects": object_count,
+            "bytes": total_bytes,
+            "version_count": version_count,
+            "version_bytes": version_bytes,
+            "total_objects": object_count + version_count,  # All objects including versions
+            "total_bytes": total_bytes + version_bytes,  # All storage including versions
+        }
         
         try:
             cache_path.parent.mkdir(parents=True, exist_ok=True)
@@ -243,6 +274,7 @@ class ObjectStorage:
         stream: BinaryIO,
         *,
         metadata: Optional[Dict[str, str]] = None,
+        enforce_quota: bool = True,
     ) -> ObjectMeta:
         bucket_path = self._bucket_path(bucket_name)
         if not bucket_path.exists():
@@ -253,13 +285,53 @@ class ObjectStorage:
         destination = bucket_path / safe_key
         destination.parent.mkdir(parents=True, exist_ok=True)
 
-        if self._is_versioning_enabled(bucket_path) and destination.exists():
+        # Check if this is an overwrite (won't add to object count)
+        is_overwrite = destination.exists()
+        existing_size = destination.stat().st_size if is_overwrite else 0
+
+        if self._is_versioning_enabled(bucket_path) and is_overwrite:
             self._archive_current_version(bucket_id, safe_key, reason="overwrite")
 
+        # Write to temp file first to get actual size
+        tmp_dir = self._system_root_path() / self.SYSTEM_TMP_DIR
+        tmp_dir.mkdir(parents=True, exist_ok=True)
+        tmp_path = tmp_dir / f"{uuid.uuid4().hex}.tmp"
+        
+        try:
             checksum = hashlib.md5()
-        with destination.open("wb") as target:
+            with tmp_path.open("wb") as target:
                 shutil.copyfileobj(_HashingReader(stream, checksum), target)
             
+            new_size = tmp_path.stat().st_size
+            
+            # Check quota before finalizing
+            if enforce_quota:
+                # Calculate net change (new size minus size being replaced)
+                size_delta = new_size - existing_size
+                object_delta = 0 if is_overwrite else 1
+                
+                quota_check = self.check_quota(
+                    bucket_name,
+                    additional_bytes=max(0, size_delta),
+                    additional_objects=object_delta,
+                )
+                if not quota_check["allowed"]:
+                    raise QuotaExceededError(
+                        quota_check["message"] or "Quota exceeded",
+                        quota_check["quota"],
+                        quota_check["usage"],
+                    )
+            
+            # Move to final destination
+            shutil.move(str(tmp_path), str(destination))
+            
+        finally:
+            # Clean up temp file if it still exists
+            try:
+                tmp_path.unlink(missing_ok=True)
+            except OSError:
+                pass
+
         stat = destination.stat()
         if metadata:
             self._write_metadata(bucket_id, safe_key, metadata)
@@ -424,6 +496,124 @@ class ObjectStorage:
         bucket_path = self._require_bucket_path(bucket_name)
         self._set_bucket_config_entry(bucket_path.name, "lifecycle", rules)
 
+    def get_bucket_quota(self, bucket_name: str) -> Dict[str, Any]:
+        """Get quota configuration for bucket.
+        
+        Returns:
+            Dict with 'max_bytes' and 'max_objects' (None if unlimited).
+        """
+        bucket_path = self._require_bucket_path(bucket_name)
+        config = self._read_bucket_config(bucket_path.name)
+        quota = config.get("quota")
+        if isinstance(quota, dict):
+            return {
+                "max_bytes": quota.get("max_bytes"),
+                "max_objects": quota.get("max_objects"),
+            }
+        return {"max_bytes": None, "max_objects": None}
+
+    def set_bucket_quota(
+        self,
+        bucket_name: str,
+        *,
+        max_bytes: Optional[int] = None,
+        max_objects: Optional[int] = None,
+    ) -> None:
+        """Set quota limits for a bucket.
+        
+        Args:
+            bucket_name: Name of the bucket
+            max_bytes: Maximum total size in bytes (None to remove limit)
+            max_objects: Maximum number of objects (None to remove limit)
+        """
+        bucket_path = self._require_bucket_path(bucket_name)
+        
+        if max_bytes is None and max_objects is None:
+            # Remove quota entirely
+            self._set_bucket_config_entry(bucket_path.name, "quota", None)
+            return
+        
+        quota: Dict[str, Any] = {}
+        if max_bytes is not None:
+            if max_bytes < 0:
+                raise StorageError("max_bytes must be non-negative")
+            quota["max_bytes"] = max_bytes
+        if max_objects is not None:
+            if max_objects < 0:
+                raise StorageError("max_objects must be non-negative")
+            quota["max_objects"] = max_objects
+        
+        self._set_bucket_config_entry(bucket_path.name, "quota", quota)
+
+    def check_quota(
+        self,
+        bucket_name: str,
+        additional_bytes: int = 0,
+        additional_objects: int = 0,
+    ) -> Dict[str, Any]:
+        """Check if an operation would exceed bucket quota.
+        
+        Args:
+            bucket_name: Name of the bucket
+            additional_bytes: Bytes that would be added
+            additional_objects: Objects that would be added
+            
+        Returns:
+            Dict with 'allowed' (bool), 'quota' (current limits),
+            'usage' (current usage), and 'message' (if not allowed).
+        """
+        quota = self.get_bucket_quota(bucket_name)
+        if not quota:
+            return {
+                "allowed": True,
+                "quota": None,
+                "usage": None,
+                "message": None,
+            }
+        
+        # Get current stats (uses cache when available)
+        stats = self.bucket_stats(bucket_name)
+        # Use totals which include versions for quota enforcement
+        current_bytes = stats.get("total_bytes", stats.get("bytes", 0))
+        current_objects = stats.get("total_objects", stats.get("objects", 0))
+        
+        result = {
+            "allowed": True,
+            "quota": quota,
+            "usage": {
+                "bytes": current_bytes,
+                "objects": current_objects,
+                "version_count": stats.get("version_count", 0),
+                "version_bytes": stats.get("version_bytes", 0),
+            },
+            "message": None,
+        }
+        
+        max_bytes_limit = quota.get("max_bytes")
+        max_objects = quota.get("max_objects")
+        
+        if max_bytes_limit is not None:
+            projected_bytes = current_bytes + additional_bytes
+            if projected_bytes > max_bytes_limit:
+                result["allowed"] = False
+                result["message"] = (
+                    f"Quota exceeded: adding {additional_bytes} bytes would result in "
+                    f"{projected_bytes} bytes, exceeding limit of {max_bytes_limit} bytes"
+                )
+                return result
+        
+        if max_objects is not None:
+            projected_objects = current_objects + additional_objects
+            if projected_objects > max_objects:
+                result["allowed"] = False
+                result["message"] = (
+                    f"Quota exceeded: adding {additional_objects} objects would result in "
+                    f"{projected_objects} objects, exceeding limit of {max_objects} objects"
+                )
+                return result
+        
+        return result
+
     def get_object_tags(self, bucket_name: str, object_key: str) -> List[Dict[str, str]]:
         """Get tags for an object."""
         bucket_path = self._bucket_path(bucket_name)
@@ -540,6 +730,7 @@ class ObjectStorage:
         else:
             self._delete_metadata(bucket_id, safe_key)
         stat = destination.stat()
+        self._invalidate_bucket_stats_cache(bucket_id)
         return ObjectMeta(
             key=safe_key.as_posix(),
             size=stat.st_size,
@@ -688,6 +879,7 @@ class ObjectStorage:
         bucket_name: str,
         upload_id: str,
         ordered_parts: List[Dict[str, Any]],
+        enforce_quota: bool = True,
     ) -> ObjectMeta:
         if not ordered_parts:
             raise StorageError("parts list required")
@@ -698,6 +890,7 @@ class ObjectStorage:
         if not parts_map:
             raise StorageError("No uploaded parts found")
         validated: List[tuple[int, Dict[str, Any]]] = []
+        total_size = 0
         for part in ordered_parts:
             raw_number = part.get("part_number")
             if raw_number is None:
@@ -717,10 +910,33 @@ class ObjectStorage:
             if supplied_etag and record.get("etag") and supplied_etag.strip('"') != record["etag"]:
                 raise StorageError(f"ETag mismatch for part {number}")
             validated.append((number, record))
+            total_size += record.get("size", 0)
         validated.sort(key=lambda entry: entry[0])
 
         safe_key = self._sanitize_object_key(manifest["object_key"])
         destination = bucket_path / safe_key
+        
+        # Check if this is an overwrite
+        is_overwrite = destination.exists()
+        existing_size = destination.stat().st_size if is_overwrite else 0
+        
+        # Check quota before writing
+        if enforce_quota:
+            size_delta = total_size - existing_size
+            object_delta = 0 if is_overwrite else 1
+            
+            quota_check = self.check_quota(
+                bucket_name,
+                additional_bytes=max(0, size_delta),
+                additional_objects=object_delta,
+            )
+            if not quota_check["allowed"]:
+                raise QuotaExceededError(
+                    quota_check["message"] or "Quota exceeded",
+                    quota_check["quota"],
+                    quota_check["usage"],
+                )
+        
         destination.parent.mkdir(parents=True, exist_ok=True)
         
         lock_file_path = self._system_bucket_root(bucket_id) / "locks" / f"{safe_key.as_posix().replace('/', '_')}.lock"

app/ui.py

@@ -260,9 +260,9 @@ def buckets_overview():
         visible_buckets.append({
             "meta": bucket,
             "summary": {
-                "objects": stats["objects"],
-                "total_bytes": stats["bytes"],
-                "human_size": _format_bytes(stats["bytes"]),
+                "objects": stats["total_objects"],
+                "total_bytes": stats["total_bytes"],
+                "human_size": _format_bytes(stats["total_bytes"]),
             },
             "access_label": access_label,
             "access_badge": access_badge,
@@ -372,6 +372,16 @@ def bucket_detail(bucket_name: str):
     encryption_enabled = current_app.config.get("ENCRYPTION_ENABLED", False)
     can_manage_encryption = can_manage_versioning  # Same as other bucket properties
 
+    # Quota settings (admin only)
+    bucket_quota = storage.get_bucket_quota(bucket_name)
+    bucket_stats = storage.bucket_stats(bucket_name)
+    can_manage_quota = False
+    try:
+        _iam().authorize(principal, None, "iam:list_users")
+        can_manage_quota = True
+    except IamError:
+        pass
+
     return render_template(
         "bucket_detail.html",
         bucket_name=bucket_name,
@@ -392,6 +402,9 @@ def bucket_detail(bucket_name: str):
         kms_keys=kms_keys,
         kms_enabled=kms_enabled,
         encryption_enabled=encryption_enabled,
+        bucket_quota=bucket_quota,
+        bucket_stats=bucket_stats,
+        can_manage_quota=can_manage_quota,
     )
 
 
@@ -925,6 +938,71 @@ def update_bucket_versioning(bucket_name: str):
     return redirect(url_for("ui.bucket_detail", bucket_name=bucket_name, tab="properties"))
 
 
+@ui_bp.post("/buckets/<bucket_name>/quota")
+def update_bucket_quota(bucket_name: str):
+    """Update bucket quota configuration (admin only)."""
+    principal = _current_principal()
+    
+    # Quota management is admin-only
+    is_admin = False
+    try:
+        _iam().authorize(principal, None, "iam:list_users")
+        is_admin = True
+    except IamError:
+        pass
+    
+    if not is_admin:
+        flash("Only administrators can manage bucket quotas", "danger")
+        return redirect(url_for("ui.bucket_detail", bucket_name=bucket_name, tab="properties"))
+    
+    action = request.form.get("action", "set")
+    
+    if action == "remove":
+        try:
+            _storage().set_bucket_quota(bucket_name, max_bytes=None, max_objects=None)
+            flash("Bucket quota removed", "info")
+        except StorageError as exc:
+            flash(_friendly_error_message(exc), "danger")
+        return redirect(url_for("ui.bucket_detail", bucket_name=bucket_name, tab="properties"))
+    
+    # Parse quota values
+    max_mb_str = request.form.get("max_mb", "").strip()
+    max_objects_str = request.form.get("max_objects", "").strip()
+    
+    max_bytes = None
+    max_objects = None
+    
+    if max_mb_str:
+        try:
+            max_mb = int(max_mb_str)
+            if max_mb < 1:
+                raise ValueError("Size must be at least 1 MB")
+            max_bytes = max_mb * 1024 * 1024  # Convert MB to bytes
+        except ValueError as exc:
+            flash(f"Invalid size value: {exc}", "danger")
+            return redirect(url_for("ui.bucket_detail", bucket_name=bucket_name, tab="properties"))
+    
+    if max_objects_str:
+        try:
+            max_objects = int(max_objects_str)
+            if max_objects < 0:
+                raise ValueError("Object count must be non-negative")
+        except ValueError as exc:
+            flash(f"Invalid object count: {exc}", "danger")
+            return redirect(url_for("ui.bucket_detail", bucket_name=bucket_name, tab="properties"))
+    
+    try:
+        _storage().set_bucket_quota(bucket_name, max_bytes=max_bytes, max_objects=max_objects)
+        if max_bytes is None and max_objects is None:
+            flash("Bucket quota removed", "info")
+        else:
+            flash("Bucket quota updated", "success")
+    except StorageError as exc:
+        flash(_friendly_error_message(exc), "danger")
+    
+    return redirect(url_for("ui.bucket_detail", bucket_name=bucket_name, tab="properties"))
+
+
 @ui_bp.post("/buckets/<bucket_name>/encryption")
 def update_bucket_encryption(bucket_name: str):
     """Update bucket default encryption configuration."""
@@ -1438,13 +1516,16 @@ def metrics_dashboard():
     
     total_objects = 0
     total_bytes_used = 0
+    total_versions = 0
     
     # Note: Uses cached stats from storage layer to improve performance
     cache_ttl = current_app.config.get("BUCKET_STATS_CACHE_TTL", 60)
     for bucket in buckets:
         stats = storage.bucket_stats(bucket.name, cache_ttl=cache_ttl)
-        total_objects += stats["objects"]
-        total_bytes_used += stats["bytes"]
+        # Use totals which include archived versions
+        total_objects += stats.get("total_objects", stats.get("objects", 0))
+        total_bytes_used += stats.get("total_bytes", stats.get("bytes", 0))
+        total_versions += stats.get("version_count", 0)
         
     return render_template(
         "metrics.html",
@@ -1465,6 +1546,7 @@ def metrics_dashboard():
         app={
             "buckets": total_buckets,
             "objects": total_objects,
+            "versions": total_versions,
             "storage_used": _format_bytes(total_bytes_used),
             "storage_raw": total_bytes_used,
         }

docs.md

@@ -340,7 +340,71 @@ To verify an object is encrypted:
 2. Look for `.meta` files containing encryption metadata
 3. Download via the API/UI - the object should be automatically decrypted
 
-## 8. Site Replication
+## 8. Bucket Quotas
+
+MyFSIO supports **storage quotas** to limit how much data a bucket can hold. Quotas are enforced on uploads and multipart completions.
+
+### Quota Types
+
+| Limit | Description |
+|-------|-------------|
+| **Max Size (MB)** | Maximum total storage in megabytes (includes current objects + archived versions) |
+| **Max Objects** | Maximum number of objects (includes current objects + archived versions) |
+
+### Managing Quotas (Admin Only)
+
+Quota management is restricted to administrators (users with `iam:*` or `iam:list_users` permissions).
+
+#### Via UI
+
+1. Navigate to your bucket in the UI
+2. Click the **Properties** tab
+3. Find the **Storage Quota** card
+4. Enter limits:
+   - **Max Size (MB)**: Leave empty for unlimited
+   - **Max Objects**: Leave empty for unlimited
+5. Click **Update Quota**
+
+To remove a quota, click **Remove Quota**.
+
+#### Via API
+
+```bash
+# Set quota (max 100MB, max 1000 objects)
+curl -X PUT "http://localhost:5000/bucket/<bucket>?quota" \
+  -H "Content-Type: application/json" \
+  -H "X-Access-Key: ..." -H "X-Secret-Key: ..." \
+  -d '{"max_bytes": 104857600, "max_objects": 1000}'
+
+# Get current quota
+curl "http://localhost:5000/bucket/<bucket>?quota" \
+  -H "X-Access-Key: ..." -H "X-Secret-Key: ..."
+
+# Remove quota
+curl -X PUT "http://localhost:5000/bucket/<bucket>?quota" \
+  -H "Content-Type: application/json" \
+  -H "X-Access-Key: ..." -H "X-Secret-Key: ..." \
+  -d '{"max_bytes": null, "max_objects": null}'
+```
+
+### Quota Behavior
+
+- **Version Counting**: When versioning is enabled, archived versions count toward the quota (similar to MinIO behavior)
+- **Enforcement Points**: Quotas are checked during `PUT` object and `CompleteMultipartUpload` operations
+- **Error Response**: When quota is exceeded, the API returns `HTTP 400` with error code `QuotaExceeded`
+- **Visibility**: All users can view quota usage in the bucket detail page, but only admins can modify quotas
+
+### Example Error
+
+```xml
+<Error>
+  <Code>QuotaExceeded</Code>
+  <Message>Bucket quota exceeded: storage limit reached</Message>
+  <BucketName>my-bucket</BucketName>
+</Error>
+```
+
+## 9. Site Replication
 
 ### Permission Model
 
@@ -477,7 +541,7 @@ To set up two-way replication (Server A ↔ Server B):
 
 **Note**: Deleting a bucket will automatically remove its associated replication configuration.
 
-## 9. Running Tests
+## 11. Running Tests
 
 ```bash
 pytest -q
@@ -487,7 +551,7 @@ The suite now includes a boto3 integration test that spins up a live HTTP server
 
 The suite covers bucket CRUD, presigned downloads, bucket policy enforcement, and regression tests for anonymous reads when a Public policy is attached.
 
-## 10. Troubleshooting
+## 12. Troubleshooting
 
 | Symptom | Likely Cause | Fix |
 | --- | --- | --- |
@@ -496,7 +560,7 @@ The suite covers bucket CRUD, presigned downloads, bucket policy enforcement, an
 | Presign modal errors with 403 | IAM user lacks `read/write/delete` for target bucket or bucket policy denies | Update IAM inline policies or remove conflicting deny statements. |
 | Large upload rejected immediately | File exceeds `MAX_UPLOAD_SIZE` | Increase env var or shrink object. |
 
-## 11. API Matrix
+## 13. API Matrix
 
 ```
 GET    /                               # List buckets
@@ -510,9 +574,11 @@ POST   /presign/<bucket>/<key>          # Generate SigV4 URL
 GET    /bucket-policy/<bucket>          # Fetch policy
 PUT    /bucket-policy/<bucket>          # Upsert policy
 DELETE /bucket-policy/<bucket>          # Delete policy
+GET    /<bucket>?quota                  # Get bucket quota
+PUT    /<bucket>?quota                  # Set bucket quota (admin only)
 ```
 
-## 12. Next Steps
+## 14. Next Steps
 
 - Tailor IAM + policy JSON files for team-ready presets.
 - Wrap `run_api.py` with gunicorn or another WSGI server for long-running workloads.

templates/bucket_detail.html

@@ -730,6 +730,158 @@
             </div>
           </div>
           {% endif %}
+
+          <!-- Storage Quota Card -->
+          <div class="card shadow-sm mt-4" id="bucket-quota-card">
+            <div class="card-header d-flex align-items-center">
+              <svg xmlns="http://www.w3.org/2000/svg" width="18" height="18" fill="currentColor" class="text-primary me-2" viewBox="0 0 16 16">
+                <path d="M1 2.5A1.5 1.5 0 0 1 2.5 1h3A1.5 1.5 0 0 1 7 2.5v3A1.5 1.5 0 0 1 5.5 7h-3A1.5 1.5 0 0 1 1 5.5v-3zM2.5 2a.5.5 0 0 0-.5.5v3a.5.5 0 0 0 .5.5h3a.5.5 0 0 0 .5-.5v-3a.5.5 0 0 0-.5-.5h-3zm6.5.5A1.5 1.5 0 0 1 10.5 1h3A1.5 1.5 0 0 1 15 2.5v3A1.5 1.5 0 0 1 13.5 7h-3A1.5 1.5 0 0 1 9 5.5v-3zm1.5-.5a.5.5 0 0 0-.5.5v3a.5.5 0 0 0 .5.5h3a.5.5 0 0 0 .5-.5v-3a.5.5 0 0 0-.5-.5h-3zM1 10.5A1.5 1.5 0 0 1 2.5 9h3A1.5 1.5 0 0 1 7 10.5v3A1.5 1.5 0 0 1 5.5 15h-3A1.5 1.5 0 0 1 1 13.5v-3zm1.5-.5a.5.5 0 0 0-.5.5v3a.5.5 0 0 0 .5.5h3a.5.5 0 0 0 .5-.5v-3a.5.5 0 0 0-.5-.5h-3zm6.5.5A1.5 1.5 0 0 1 10.5 9h3a1.5 1.5 0 0 1 1.5 1.5v3a1.5 1.5 0 0 1-1.5 1.5h-3A1.5 1.5 0 0 1 9 13.5v-3zm1.5-.5a.5.5 0 0 0-.5.5v3a.5.5 0 0 0 .5.5h3a.5.5 0 0 0 .5-.5v-3a.5.5 0 0 0-.5-.5h-3z"/>
+              </svg>
+              <span class="fw-semibold">Storage Quota</span>
+            </div>
+            <div class="card-body">
+              {% set max_bytes = bucket_quota.get('max_bytes') %}
+              {% set max_objects = bucket_quota.get('max_objects') %}
+              {% set has_quota = max_bytes is not none or max_objects is not none %}
+              {% set current_objects = bucket_stats.get('objects', 0) %}
+              {% set version_count = bucket_stats.get('version_count', 0) %}
+              {% set total_objects = bucket_stats.get('total_objects', current_objects) %}
+              {% set current_bytes = bucket_stats.get('bytes', 0) %}
+              {% set version_bytes = bucket_stats.get('version_bytes', 0) %}
+              {% set total_bytes = bucket_stats.get('total_bytes', current_bytes) %}
+              
+              <!-- Current Usage Display -->
+              <div class="mb-4">
+                <h6 class="small fw-semibold mb-3">Current Usage</h6>
+                <div class="row g-3">
+                  <div class="col-6">
+                    <div class="border rounded p-3 text-center">
+                      <div class="fs-4 fw-bold text-primary">{{ total_objects }}</div>
+                      <div class="small text-muted">Total Objects</div>
+                      {% if max_objects is not none %}
+                      <div class="progress mt-2" style="height: 4px;">
+                        {% set obj_pct = (total_objects / max_objects * 100) | int if max_objects > 0 else 0 %}
+                        <div class="progress-bar {% if obj_pct >= 90 %}bg-danger{% elif obj_pct >= 75 %}bg-warning{% else %}bg-success{% endif %}" style="width: {{ [obj_pct, 100] | min }}%"></div>
+                      </div>
+                      <div class="small text-muted mt-1">{{ obj_pct }}% of {{ max_objects }} limit</div>
+                      {% else %}
+                      <div class="small text-muted mt-2">No limit</div>
+                      {% endif %}
+                      {% if version_count > 0 %}
+                      <div class="small text-muted mt-1">
+                        <span class="text-body-secondary">({{ current_objects }} current + {{ version_count }} versions)</span>
+                      </div>
+                      {% endif %}
+                    </div>
+                  </div>
+                  <div class="col-6">
+                    <div class="border rounded p-3 text-center">
+                      <div class="fs-4 fw-bold text-primary">{{ total_bytes | filesizeformat }}</div>
+                      <div class="small text-muted">Total Storage</div>
+                      {% if max_bytes is not none %}
+                      <div class="progress mt-2" style="height: 4px;">
+                        {% set bytes_pct = (total_bytes / max_bytes * 100) | int if max_bytes > 0 else 0 %}
+                        <div class="progress-bar {% if bytes_pct >= 90 %}bg-danger{% elif bytes_pct >= 75 %}bg-warning{% else %}bg-success{% endif %}" style="width: {{ [bytes_pct, 100] | min }}%"></div>
+                      </div>
+                      <div class="small text-muted mt-1">{{ bytes_pct }}% of {{ max_bytes | filesizeformat }} limit</div>
+                      {% else %}
+                      <div class="small text-muted mt-2">No limit</div>
+                      {% endif %}
+                      {% if version_bytes > 0 %}
+                      <div class="small text-muted mt-1">
+                        <span class="text-body-secondary">({{ current_bytes | filesizeformat }} current + {{ version_bytes | filesizeformat }} versions)</span>
+                      </div>
+                      {% endif %}
+                    </div>
+                  </div>
+                </div>
+              </div>
+
+              {% if has_quota %}
+              <!-- Quota Enabled State -->
+              <div class="alert alert-info d-flex align-items-start mb-4" role="alert">
+                <svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" fill="currentColor" class="me-2 flex-shrink-0" viewBox="0 0 16 16">
+                  <path d="M8 16A8 8 0 1 0 8 0a8 8 0 0 0 0 16zm.93-9.412-1 4.705c-.07.34.029.533.304.533.194 0 .487-.07.686-.246l-.088.416c-.287.346-.92.598-1.465.598-.703 0-1.002-.422-.808-1.319l.738-3.468c.064-.293.006-.399-.287-.47l-.451-.081.082-.381 2.29-.287zM8 5.5a1 1 0 1 1 0-2 1 1 0 0 1 0 2z"/>
+                </svg>
+                <div>
+                  <strong>Storage quota enabled</strong>
+                  <p class="mb-0 small">
+                    {% if max_bytes is not none and max_objects is not none %}
+                    Limited to {{ max_bytes | filesizeformat }} and {{ max_objects }} objects.
+                    {% elif max_bytes is not none %}
+                    Limited to {{ max_bytes | filesizeformat }} storage.
+                    {% else %}
+                    Limited to {{ max_objects }} objects.
+                    {% endif %}
+                  </p>
+                </div>
+              </div>
+              {% else %}
+              <!-- Quota Disabled State -->
+              <div class="alert alert-secondary d-flex align-items-start mb-4" role="alert">
+                <svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" fill="currentColor" class="me-2 flex-shrink-0" viewBox="0 0 16 16">
+                  <path d="M8 15A7 7 0 1 1 8 1a7 7 0 0 1 0 14zm0 1A8 8 0 1 0 8 0a8 8 0 0 0 0 16z"/>
+                  <path d="M4.646 4.646a.5.5 0 0 1 .708 0L8 7.293l2.646-2.647a.5.5 0 0 1 .708.708L8.707 8l2.647 2.646a.5.5 0 0 1-.708.708L8 8.707l-2.646 2.647a.5.5 0 0 1-.708-.708L7.293 8 4.646 5.354a.5.5 0 0 1 0-.708z"/>
+                </svg>
+                <div>
+                  <strong>No storage quota</strong>
+                  <p class="mb-0 small">This bucket has no storage or object count limits. Set limits below to control usage.</p>
+                </div>
+              </div>
+              {% endif %}
+
+              {% if can_manage_quota %}
+              <form method="post" action="{{ url_for('ui.update_bucket_quota', bucket_name=bucket_name) }}" id="quotaForm">
+                <input type="hidden" name="csrf_token" value="{{ csrf_token() }}" />
+                
+                <!-- Max Storage -->
+                <div class="mb-3">
+                  <label for="max_mb" class="form-label fw-medium">Maximum Storage Size</label>
+                  <div class="input-group">
+                    <input type="number" class="form-control" id="max_mb" name="max_mb" 
+                           value="{{ (max_bytes / 1048576) | int if max_bytes is not none else '' }}" 
+                           min="1" step="1" placeholder="Unlimited">
+                    <span class="input-group-text">MB</span>
+                  </div>
+                  <div class="form-text">Minimum 1 MB. Leave empty for unlimited.</div>
+                </div>
+
+                <!-- Max Objects -->
+                <div class="mb-4">
+                  <label for="max_objects" class="form-label fw-medium">Maximum Object Count</label>
+                  <input type="number" class="form-control" id="max_objects" name="max_objects" 
+                         value="{{ max_objects if max_objects is not none else '' }}" 
+                         min="0" step="1" placeholder="Unlimited">
+                  <div class="form-text">Maximum number of objects allowed. Leave empty for unlimited.</div>
+                </div>
+
+                <div class="d-flex gap-2 flex-wrap">
+                  <button class="btn btn-primary" type="submit">
+                    <svg xmlns="http://www.w3.org/2000/svg" width="14" height="14" fill="currentColor" class="me-1" viewBox="0 0 16 16">
+                      <path d="M12.736 3.97a.733.733 0 0 1 1.047 0c.286.289.29.756.01 1.05L7.88 12.01a.733.733 0 0 1-1.065.02L3.217 8.384a.757.757 0 0 1 0-1.06.733.733 0 0 1 1.047 0l3.052 3.093 5.4-6.425a.247.247 0 0 1 .02-.022Z"/>
+                    </svg>
+                    Save Quota Settings
+                  </button>
+                  {% if has_quota %}
+                  <button type="submit" class="btn btn-outline-danger" id="removeQuotaBtn" name="action" value="remove">
+                    <svg xmlns="http://www.w3.org/2000/svg" width="14" height="14" fill="currentColor" class="me-1" viewBox="0 0 16 16">
+                      <path d="M4.646 4.646a.5.5 0 0 1 .708 0L8 7.293l2.646-2.647a.5.5 0 0 1 .708.708L8.707 8l2.647 2.646a.5.5 0 0 1-.708.708L8 8.707l-2.646 2.647a.5.5 0 0 1-.708-.708L7.293 8 4.646 5.354a.5.5 0 0 1 0-.708z"/>
+                    </svg>
+                    Remove Quota
+                  </button>
+                  {% endif %}
+                </div>
+              </form>
+              {% else %}
+              <div class="text-center py-3">
+                <svg xmlns="http://www.w3.org/2000/svg" width="32" height="32" fill="currentColor" class="text-muted mb-2" viewBox="0 0 16 16">
+                  <path d="M8 1a2 2 0 0 1 2 2v4H6V3a2 2 0 0 1 2-2zm3 6V3a3 3 0 0 0-6 0v4a2 2 0 0 0-2 2v5a2 2 0 0 0 2 2h6a2 2 0 0 0 2-2V9a2 2 0 0 0-2-2z"/>
+                </svg>
+                <p class="text-muted mb-0 small">You do not have permission to modify quota settings for this bucket.</p>
+              </div>
+              {% endif %}
+            </div>
+          </div>
         </div>
 
         <!-- Sidebar -->

templates/docs.html

@@ -418,10 +418,78 @@ s3.complete_multipart_upload(
         </p>
       </div>
     </article>
+    <article id="quotas" class="card shadow-sm docs-section">
+      <div class="card-body">
+        <div class="d-flex align-items-center gap-2 mb-3">
+          <span class="docs-section-kicker">10</span>
+          <h2 class="h4 mb-0">Bucket Quotas</h2>
+        </div>
+        <p class="text-muted">Limit how much data a bucket can hold using storage quotas. Quotas are enforced on uploads and multipart completions.</p>
+        
+        <h3 class="h6 text-uppercase text-muted mt-4">Quota Types</h3>
+        <div class="table-responsive mb-3">
+          <table class="table table-sm table-bordered small">
+            <thead class="table-light">
+              <tr>
+                <th>Limit</th>
+                <th>Description</th>
+              </tr>
+            </thead>
+            <tbody>
+              <tr>
+                <td><strong>Max Size (MB)</strong></td>
+                <td>Maximum total storage in megabytes (includes current objects + archived versions)</td>
+              </tr>
+              <tr>
+                <td><strong>Max Objects</strong></td>
+                <td>Maximum number of objects (includes current objects + archived versions)</td>
+              </tr>
+            </tbody>
+          </table>
+        </div>
+
+        <h3 class="h6 text-uppercase text-muted mt-4">Managing Quotas (Admin Only)</h3>
+        <p class="small text-muted">Quota management is restricted to administrators (users with <code>iam:*</code> permissions).</p>
+        <ol class="docs-steps mb-3">
+          <li>Navigate to your bucket → <strong>Properties</strong> tab → <strong>Storage Quota</strong> card.</li>
+          <li>Enter limits: <strong>Max Size (MB)</strong> and/or <strong>Max Objects</strong>. Leave empty for unlimited.</li>
+          <li>Click <strong>Update Quota</strong> to save, or <strong>Remove Quota</strong> to clear limits.</li>
+        </ol>
+
+        <h3 class="h6 text-uppercase text-muted mt-4">API Usage</h3>
+<pre class="mb-3"><code class="language-bash"># Set quota (max 100MB, max 1000 objects)
+curl -X PUT "{{ api_base }}/bucket/&lt;bucket&gt;?quota" \
+  -H "Content-Type: application/json" \
+  -H "X-Access-Key: &lt;key&gt;" -H "X-Secret-Key: &lt;secret&gt;" \
+  -d '{"max_bytes": 104857600, "max_objects": 1000}'
+
+# Get current quota
+curl "{{ api_base }}/bucket/&lt;bucket&gt;?quota" \
+  -H "X-Access-Key: &lt;key&gt;" -H "X-Secret-Key: &lt;secret&gt;"
+
+# Remove quota
+curl -X PUT "{{ api_base }}/bucket/&lt;bucket&gt;?quota" \
+  -H "Content-Type: application/json" \
+  -H "X-Access-Key: &lt;key&gt;" -H "X-Secret-Key: &lt;secret&gt;" \
+  -d '{"max_bytes": null, "max_objects": null}'</code></pre>
+
+        <div class="alert alert-light border mb-0">
+          <div class="d-flex gap-2">
+            <svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-info-circle text-muted mt-1" viewBox="0 0 16 16">
+              <path d="M8 15A7 7 0 1 1 8 1a7 7 0 0 1 0 14zm0 1A8 8 0 1 0 8 0a8 8 0 0 0 0 16z"/>
+              <path d="m8.93 6.588-2.29.287-.082.38.45.083c.294.07.352.176.288.469l-.738 3.468c-.194.897.105 1.319.808 1.319.545 0 1.178-.252 1.465-.598l.088-.416c-.2.176-.492.246-.686.246-.275 0-.375-.193-.304-.533L8.93 6.588zM9 4.5a1 1 0 1 1-2 0 1 1 0 0 1 2 0z"/>
+            </svg>
+            <div>
+              <strong>Version Counting:</strong> When versioning is enabled, archived versions count toward the quota (similar to MinIO behavior). The quota is checked against total storage, not just current objects.
+            </div>
+          </div>
+        </div>
+      </div>
+    </article>
     <article id="encryption" class="card shadow-sm docs-section">
       <div class="card-body">
         <div class="d-flex align-items-center gap-2 mb-3">
-          <span class="docs-section-kicker">09</span>
+          <span class="docs-section-kicker">11</span>
           <h2 class="h4 mb-0">Encryption</h2>
         </div>
         <p class="text-muted">Protect data at rest with server-side encryption using AES-256-GCM. Objects are encrypted before being written to disk and decrypted transparently on read.</p>
@@ -515,7 +583,7 @@ curl -X DELETE "{{ api_base }}/kms/keys/{key-id}?waiting_period_days=30" \
     <article id="troubleshooting" class="card shadow-sm docs-section">
       <div class="card-body">
         <div class="d-flex align-items-center gap-2 mb-3">
-          <span class="docs-section-kicker">10</span>
+          <span class="docs-section-kicker">12</span>
           <h2 class="h4 mb-0">Troubleshooting &amp; tips</h2>
         </div>
         <div class="table-responsive">
@@ -572,6 +640,7 @@ curl -X DELETE "{{ api_base }}/kms/keys/{key-id}?waiting_period_days=30" \
           <li><a href="#api">REST endpoints</a></li>
           <li><a href="#examples">API Examples</a></li>
           <li><a href="#replication">Site Replication</a></li>
+          <li><a href="#quotas">Bucket Quotas</a></li>
           <li><a href="#encryption">Encryption</a></li>
           <li><a href="#troubleshooting">Troubleshooting</a></li>
         </ul>