Zappa: Effortless Serverless Python Web Apps on AWS Lambda

Introduction

Zappa is an open-source tool that makes it incredibly easy to build and deploy serverless, event-driven Python applications on AWS Lambda and API Gateway. It transforms your existing Python web applications, including popular frameworks like Django and Flask, into highly scalable, zero-downtime, and zero-maintenance serverless solutions. With Zappa, you only pay for the milliseconds of server time you use, often resulting in significant cost savings compared to traditional hosting.

Installation

Before you begin, ensure you are running Python 3.8 or newer and have a valid AWS account with properly configured AWS credentials. Zappa should be installed within your project's virtual environment.

To install Zappa, use pip:

$ pip install zappa

After installation, you can initialize your project settings:

$ zappa init

This command automatically detects your application type (Flask/Django) and helps you create a zappa_settings.json file, which defines your deployment configuration. For example, a basic Flask app might look like this:

{
    "dev": {
        "s3_bucket": "your-lambda-bucket",
        "app_function": "your_module.app"
    }
}

Examples

Once your settings are configured, deploying your application to a stage like "production" is straightforward:

$ zappa deploy production

Your application will then be live, with Zappa handling packaging, S3 upload, IAM roles, Lambda function creation, and API Gateway setup.

To update your deployed code without changing routes:

$ zappa update production

If you need to revert to a previous version, you can use the rollback command:

$ zappa rollback production -n 3

Zappa also allows you to schedule functions to run at regular intervals, replacing traditional task queues:

{
    "production": {
       "events": [{
           "function": "your_module.your_function",
           "expression": "rate(1 minute)"
       }]
    }
}

Then, schedule it with:

$ zappa schedule production

You can also invoke any function in your application directly on Lambda:

$ zappa invoke production my_app.my_function

For Django projects, Zappa provides a convenient way to run management commands remotely:

$ zappa manage production showmigrations admin

Why Use Zappa

Zappa offers a compelling solution for deploying Python applications to the cloud. It provides infinite scalability, automatically handling traffic spikes without manual intervention. The pay-per-use model of AWS Lambda makes it incredibly cost-effective, often resulting in free usage for low-traffic applications. Zappa supports popular WSGI frameworks like Django, Flask, and Bottle, usually requiring no changes to your existing codebase.

Beyond basic deployment, Zappa includes advanced features such as free SSL certificates, global application deployment across AWS regions, API access management, automatic security policy generation, precompiled C-extensions, and automatic "keep-warm" events to minimize cold starts. Its ease of use, with single-command deployment, makes it an attractive choice for developers looking to leverage serverless architectures without the complexity.

Links

• GitHub Repository: https://github.com/zappa/Zappa
• Zappa Slack Auto Invite: https://slackautoinviter.herokuapp.com