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AWS Lambda Handler Cookbook - A Serverless Service Template


The Problem

Starting a Serverless service can be overwhelming. You need to figure out many questions and challenges that have nothing to do with your business domain:

  • How to deploy to the cloud? What IAC framework do you choose?
  • How to write a SaaS-oriented CI/CD pipeline? What does it need to contain?
  • How do you handle observability, logging, tracing, metrics?
  • How do you handle testing?

The Solution

This project aims to reduce cognitive load and answer these questions for you by providing a skeleton Python Serverless service template that implements best practices for AWS Lambda, Serverless CI/CD, and AWS CDK in one template project.

Serverless Service - The Order service


  • This project provides a working orders service where customers can create orders of items.

  • The project deploys an API GW with an AWS Lambda integration under the path POST /api/orders/ and stores orders data in a DynamoDB table.

Monitoring Design



I spoke at AWS re:invent 2023 with Heitor Lessa, Chief Architect of Powertools for AWS Lambda about the concepts I implemented in this project.


  • Python Serverless service with a recommended file structure.
  • CDK infrastructure with infrastructure tests and security tests.
  • CI/CD pipelines based on Github actions that deploys to AWS with python linters, complexity checks and style formatters.
  • CI/CD pipeline deploys to dev/staging and production environment with different gates between each environment
  • Makefile for simple developer experience.
  • The AWS Lambda handler embodies Serverless best practices and has all the bells and whistles for a proper production ready handler.
  • AWS Lambda handler uses AWS Lambda Powertools.
  • AWS Lambda handler 3 layer architecture: handler layer, logic layer and data access layer
  • Features flags and configuration based on AWS AppConfig
  • CloudWatch dashboards - High level and low level including CloudWatch alarms
  • Idempotent API
  • REST API protected by WAF with four AWS managed rules in production deployment
  • Unit, infrastructure, security, integration and E2E tests.
  • Automatically generated OpenAPI endpoint: /swagger with Pydantic schemas for both requests and responses
  • Automated protection against API breaking changes

The GitHub template project can be found at

Serverless Best Practices

The AWS Lambda handler will implement multiple best practice utilities.

Each utility is implemented when a new blog post is published about that utility.

The utilities cover multiple aspects of a production-ready service, including:

While the code examples are written in Python, the principles are valid to any supported AWS Lambda handler programming language.


This library is licensed under the MIT License. See the LICENSE file.