New serverless pattern - lambda-bedrock-mantle-responses-api-cdk

[NithinChandranR-AWS]

New Serverless Pattern: Amazon Bedrock Mantle Responses API with AWS Lambda (OpenAI SDK Compatible)

Description

Deploys an API Gateway + Lambda function that calls Amazon Bedrock via the OpenAI-compatible Responses API (bedrock-mantle endpoint) using the standard OpenAI Python SDK. Shows customers how to migrate existing OpenAI applications to Bedrock with minimal code changes — just swap the base URL and API key.

Architecture

Client -> API Gateway (POST /ask) -> Lambda (OpenAI Python SDK) -> bedrock-mantle.{region}.api.aws/v1

Key Features

• First Bedrock Mantle / OpenAI-compatible Responses API pattern in this repo
• Uses standard OpenAI Python SDK with only base_url and api_key changed
• No bedrock:InvokeModel IAM permission needed (auth via Bedrock API key)
• Stateful conversation support via previous_response_id
• Default model: openai.gpt-oss-120b (OpenAI GPT on Bedrock)
• try/catch error handling with structured 500 responses

Framework / Language

• AWS CDK (TypeScript)
• Lambda: Python 3.12 (OpenAI SDK)

Changes

• lib/stack.ts — CDK stack: Lambda with bundled openai package, API Gateway REST API, CfnParameter for API key
• src/index.py — Lambda handler using client.responses.create()
• src/requirements.txt — openai
• README.md — Architecture, prerequisites (Bedrock API key generation), deployment, testing with curl
• example-pattern.json — Pattern metadata

Testing

• CDK synth verified
• Deployed to AWS, tested end-to-end via curl
• Response: {"response": "Amazon Bedrock is a fully managed AWS service...", "model": "openai.gpt-oss-120b", "id": "resp_..."}
• Error handling verified (invalid model returns structured 500)