s3func 0.8.3

Simple functions for working with S3

s3func

Simple functions for working with S3 and B2

---

s3func is a lightweight Python library providing a simplified interface for interacting with S3-compatible object storage services and Backblaze B2. It removes the boto3 dependency in favor of a fast, urllib3-based client with custom SigV4 signing.

Key Features

• Zero Boto3 Dependency: Minimal overhead and faster imports.
• S3 & B2 Support: Unified interface for both AWS S3 (and compatible) and Backblaze B2 native API.
• Distributed Locking: Robust shared and exclusive locking mechanism using object storage.
• Streaming Support: Efficiently stream large objects.
• Automatic Retries: Built-in adaptive retry logic for transient network issues.

Installation

pip install s3func

Usage Examples

S3 Operations

from s3func import S3Session

# Initialize session for AWS S3
session = S3Session(
    access_key_id='YOUR_ACCESS_KEY',
    access_key='YOUR_SECRET_KEY',
    bucket='my-bucket',
    region='us-east-1'
)

# Also works with other S3-compatible providers (Contabo, Wasabi, DigitalOcean, etc.)
# by providing an endpoint_url.
session = S3Session(
    access_key_id='YOUR_ACCESS_KEY',
    access_key='YOUR_SECRET_KEY',
    bucket='my-bucket',
    endpoint_url='https://eu2.contabostorage.com'
)

# Upload an object
session.put_object('hello.txt', b'Hello, S3!')

# Download an object
resp = session.get_object('hello.txt')
print(resp.data.decode())

# List objects
for obj in session.list_objects(prefix='logs/').iter_objects():
    print(obj['key'], obj['content_length'])

Custom Metadata

You can easily read and write custom metadata headers.

# Upload with metadata
session.put_object(
    'data.csv', 
    b'col1,col2\n1,2', 
    metadata={'processed': 'false', 'source': 'sensor-1'}
)

# Read metadata
resp = session.head_object('data.csv')
print(resp.metadata['processed']) # 'false'

Backblaze B2 Operations

s3func uses the B2 native API for better performance and reliability on Backblaze.

from s3func import B2Session

# Initialize B2 session
session = B2Session(
    access_key_id='YOUR_APPLICATION_KEY_ID',
    access_key='YOUR_APPLICATION_KEY',
    bucket='my-b2-bucket'
)

# Put object
session.put_object('data.json', b'{"status": "ok"}', content_type='application/json')

Distributed Locking

s3func provides a powerful distributed lock that mimics Python's threading.Lock API.

# Using S3 Lock via context manager
with session.lock('process-1'):
    # This block is protected by a distributed lock
    print("Doing some exclusive work...")

# Explicit acquire/release with timeout
lock = session.lock('my-resource')
if lock.acquire(blocking=True, timeout=10):
    try:
        # Perform operation
        pass
    finally:
        lock.release()

Performance Tips

• Streaming: Set stream=True in the session (default) or individual requests to handle large files without loading them entirely into memory.
• B2 Authorization Caching: s3func automatically caches B2 authorization tokens globally for up to 1 hour, significantly reducing latency for concurrent operations.
• Adaptive Retries: The library uses urllib3 retry logic configured for high-concurrency environments to handle rate limiting and network blips automatically.

How Distributed Locking Works

The locking mechanism uses a "two-object sequential" protocol to ensure safety even in eventually consistent systems:

1. Acquisition: A worker writes two small objects (seq-0 and seq-1) to the storage provider.
2. Verification: It then lists all existing lock objects for that resource.
3. Conflict Resolution: A worker "wins" the lock if its seq-1 timestamp is the earliest among all candidates. If timestamps are identical, the lexicographical order of a unique lock_id acts as a tie-breaker.
4. Auto-Cleanup: Uses weakref.finalize to ensure lock objects are deleted even if the process exits unexpectedly (best effort).

Development

Setup environment

We use uv to manage the development environment and production build.

uv sync --all-extras --dev

Running Tests

uv run pytest

License

This project is licensed under the terms of the Apache Software License 2.0.