Zappa — Serverless Python Web Apps on AWS Lambda

Introduction

Zappa makes it simple to deploy standard Python WSGI applications — Django, Flask, Bottle, and others — to AWS Lambda and API Gateway. It eliminates server management while keeping the familiar Python web framework workflow intact.

What Zappa Does

• Packages and deploys any WSGI-compatible Python app to AWS Lambda
• Automatically configures API Gateway as the HTTP frontend
• Handles CloudWatch event scheduling for periodic tasks
• Manages multiple deployment stages (dev, staging, production)
• Supports binary uploads, large projects via S3 slim packaging, and async task execution

Architecture Overview

Zappa wraps your Python application in a Lambda-compatible handler that translates API Gateway events into WSGI requests. It uses S3 for deployment artifact storage, CloudFormation for resource provisioning, and CloudWatch Events for scheduled tasks. The entire infrastructure is managed through a single zappa_settings.json file.

Self-Hosting & Configuration

• Install with pip install zappa inside a virtualenv
• Run zappa init to generate zappa_settings.json interactively
• Configure s3_bucket, aws_region, and runtime in settings
• Set slim_handler: true for projects exceeding Lambda's 50 MB package limit
• Use zappa schedule and zappa unschedule for cron-style recurring tasks

Key Features

• Zero-downtime deployments with automatic rollback support
• Native Django and Flask support with management command passthrough
• Async task execution via @task decorator without a separate queue
• Let's Encrypt SSL certificate provisioning with zappa certify
• Tail CloudWatch logs in real time with zappa tail

Comparison with Similar Tools

• Serverless Framework — multi-cloud, YAML-heavy; Zappa is Python-only but requires no boilerplate
• AWS Chalice — AWS-native micro-framework; Zappa deploys full WSGI apps, not just API handlers
• AWS SAM — CloudFormation-based; Zappa abstracts away all template management
• Mangum — ASGI adapter for Lambda; Zappa handles WSGI and includes full deployment tooling

FAQ

Q: Which Python frameworks does Zappa support? A: Any WSGI-compatible framework including Django, Flask, Bottle, Falcon, and Pyramid.

Q: Can Zappa handle large projects? A: Yes. The slim handler option uploads code to S3 and loads it at invocation time, bypassing Lambda's package size limit.

Q: Is Zappa still maintained? A: The original repo is in maintenance mode. Community forks continue active development.

Q: Does Zappa support async Python? A: Zappa itself targets WSGI (synchronous). For ASGI apps, Mangum is the recommended alternative.

Sources

• https://github.com/Miserlou/Zappa
• https://github.com/zappa/Zappa