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)

[marcojahn]

Hello @NithinChandranR-AWS.
Thank you for your contribution! After reviewing this submission, we've determined that Architecturally identical to the existing apigw-lambda-bedrock patterns: API Gateway -> Lambda -> Bedrock. The only difference is calling Bedrock through the OpenAI-compatible Responses API base URL with the OpenAI SDK — an SDK/endpoint swap, not a new wiring.

The Serverless Patterns Collection focuses on IaC-focused implementations of 2-4 AWS services in commonly used architectural combinations, where the serverless component is integral to the design.

If you believe this assessment is incorrect, please let us know what architectural distinction we may have missed.

[NithinChandranR-AWS]

That's a fair assessment — the architecture is the same underlying APIGW → Lambda → Bedrock wiring, just using the OpenAI-compatible endpoint. Closing this. Thank you for your time and help.