Local Files Storage

Overview

Local Files storage lets self-hosted Label Studio read media (images, audio, video, documents) directly from the server's filesystem and write annotation results back to disk. It's designed for air-gapped environments or workflows where data cannot leave the host machine.

Three core operations:
1. Import/Sync – scan a directory, create tasks pointing to local files
2. Serve – stream file bytes to the labeling UI via /data/local-files/?d=...
3. Export – write completed annotations as JSON files to a target directory

Architecture

flowchart TB
    subgraph Configuration
        ENV["Environment variables
        LOCAL_FILES_SERVING_ENABLED
        LOCAL_FILES_DOCUMENT_ROOT"]
        AUTO["Community auto-detect
        mydata / label-studio-data"]
    end

    subgraph "Import Flow"
        UI_IMPORT["UI: Add Source Storage"] --> SERIALIZER["Serializer
        normalize path
        validate_connection"]
        SERIALIZER --> IMPORT_STORAGE["LocalFilesImportStorage"]
        IMPORT_STORAGE --> SYNC["Sync button"]
        SYNC --> ITER["iter_objects
        scan directory"]
        ITER --> |use_blob_urls=true| BLOB_TASK["Create task with URL
        /data/local-files/?d=path"]
        ITER --> |use_blob_urls=false| JSON_TASK["Read JSON file
        as task definition"]
        BLOB_TASK --> TASK_DB["Tasks in DB"]
        JSON_TASK --> TASK_DB
        TASK_DB --> LINK["LocalFilesImportStorageLink"]
    end

    subgraph "File Serving Flow"
        LABEL_UI["Labeling UI requests
        /data/local-files/?d=relative/path"] --> VIEW["localfiles_data view"]
        VIEW --> AUTH["Check authentication"]
        AUTH --> PATH_CHECK["Normalize path
        safe_join with DOCUMENT_ROOT"]
        PATH_CHECK --> PERM["Find storages where
        storage.path is prefix of file dir"]
        PERM --> PROJECT_PERM["Check project.has_permission"]
        PROJECT_PERM --> |allowed| SERVE["Stream file with ETag
        RangedFileResponse"]
        PROJECT_PERM --> |denied| FORBIDDEN["403 Forbidden"]
        PATH_CHECK --> |not found| NOTFOUND["404 Not Found"]
    end

    subgraph "Export Flow"
        ANNOTATION["Annotation saved"] --> SIGNAL["post_save signal"]
        SIGNAL --> EXPORT_STORAGE["LocalFilesExportStorage
        save_annotation"]
        EXPORT_STORAGE --> WRITE["Write JSON to
        storage.path/annotation_id.json"]
        WRITE --> EXPORT_LINK["LocalFilesExportStorageLink"]
        DELETE["Annotation deleted"] --> DEL_SIGNAL["pre_delete signal"]
        DEL_SIGNAL --> DEL_FILE["delete_annotation
        removes JSON file"]
    end

    ENV --> SERIALIZER
    AUTO --> ENV

Key Concepts

Storage Models

Import Modes

When syncing an import storage, use_blob_urls determines how files become tasks:

• use_blob_urls=True (default "Files" mode): Each file becomes a task with a single data field pointing to /data/local-files/?d=<relative_path>. Best for labeling images, audio, video.

• use_blob_urls=False ("Tasks" mode): Each .json/.jsonl file is parsed as task definitions. Use this when your tasks have complex structures or multiple data fields.

Path Handling

All storage paths are normalized before saving:
- Trailing slashes removed (/data/images/ → /data/images)
- Backslashes converted to OS separator (C:\data → C:/data on Linux)
- Redundant separators collapsed (/data//images → /data/images)

This prevents 404 errors caused by path mismatches between stored paths and request paths.

Permission Model

The /data/local-files/?d=... endpoint enforces:
1. User must be authenticated
2. LOCAL_FILES_SERVING_ENABLED must be true
3. Requested file's directory must be inside at least one LocalFilesImportStorage.path
4. User must have permission on that storage's project

Configuration

Environment Variables

Variables can be prefixed with LABEL_STUDIO_ or HEARTEX_ (checked in that order).

Community Edition Auto-Detection

When both LOCAL_FILES_DOCUMENT_ROOT and LOCAL_FILES_SERVING_ENABLED are unset, Community Edition automatically searches for mydata or label-studio-data directories in the current working directory. If found, it enables local file serving with that directory as the document root.

Docker shortcut: Mount your host folder to /label-studio/mydata inside the container to enable local files without setting any environment variables.

Production Setup

export LABEL_STUDIO_LOCAL_FILES_SERVING_ENABLED=true
export LABEL_STUDIO_LOCAL_FILES_DOCUMENT_ROOT=/data/labelstudio

# Directory structure:
# /data/labelstudio/           ← DOCUMENT_ROOT
# /data/labelstudio/project1/  ← Storage path for project 1
# /data/labelstudio/project2/  ← Storage path for project 2

Usage

Creating Tasks with Local Files

1. Configure import storage in project Settings → Cloud Storage → Add Source Storage → Local Files
2. Set Absolute local path to a subdirectory of LOCAL_FILES_DOCUMENT_ROOT
3. Choose import method:

• Files: auto-create one task per media file
• Tasks: read JSON/JSONL files as task definitions

1. Click Sync to scan the directory and create tasks

Manual Task Import

When importing tasks via JSON, reference local files with:

{
  "data": {
    "image": "/data/local-files/?d=project1/images/photo.jpg",
    "audio": "/data/local-files/?d=project1/audio/recording.wav"
  }
}

The path after ?d= is relative to LOCAL_FILES_DOCUMENT_ROOT.

Exporting Annotations

1. Configure target storage in project Settings → Cloud Storage → Add Target Storage → Local Files
2. Annotations are automatically written as JSON when saved
3. Files are named <annotation_id>.json inside the storage path

API Reference

REST Endpoints

File Serving Details

The /data/local-files/ view (views.py):
- Returns 403 if serving disabled or user lacks permission
- Returns 404 if file doesn't exist or no matching storage
- Returns 304 Not Modified if client's If-None-Match matches current ETag
- Supports HTTP Range requests for video/audio seeking

Files Reference

Troubleshooting

Common Issues

Debug Steps

1. Check environment:
   bash echo $LABEL_STUDIO_LOCAL_FILES_SERVING_ENABLED echo $LABEL_STUDIO_LOCAL_FILES_DOCUMENT_ROOT

2. Test file access directly:
   curl -I "http://localhost:8080/data/local-files/?d=project1/test.jpg"

Don't forget to add -H with authorization token.

1. Verify storage configuration in Django shell:
   python from io_storages.localfiles.models import LocalFilesImportStorage for s in LocalFilesImportStorage.objects.all(): print(f"{s.project.title}: {s.path}")

Security Considerations

• Disable by default: LOCAL_FILES_SERVING_ENABLED=false prevents accidental exposure
• Path containment: All requests validated against LOCAL_FILES_DOCUMENT_ROOT
• Project permissions: Users can only access files linked to projects they have access to
• No directory listing: Only explicit file paths are served

Warning: Do not enable local file serving on public multi-tenant deployments. The feature is designed for on-premise single-tenant environments.