Stateless MCP on AWS Lambda (Python)

This project demonstrates how to deploy a stateless MCP (Message Control Protocol) server on AWS Lambda using Python. The implementation uses AWS API Gateway for HTTP endpoints and AWS Lambda for serverless execution.

Prerequisites

• AWS CLI configured with appropriate credentials
• Python 3.x
• Make
• AWS SAM CLI
• Docker Desktop or Podman for local builds
• MCP Inspector tool for testing

Project Structure

stateless-mcp-on-lambda-python/
├── build/         # Build artifacts
├── etc/           # Configuration files
├── sam/           # SAM template files
├── src/           # Source code
├── tmp/           # Temporary files
└── makefile       # Build and deployment commands

Configuration

Before deploying, you need to configure the environment variables in etc/environment.sh:

1. AWS Configuration:

   • PROFILE: Your AWS CLI profile name
   • BUCKET: S3 bucket name for deployment artifacts
   • REGION: AWS region (default: us-east-1)

2. MCP Dependencies:

   • P_DESCRIPTION: MCP package version (default: "mcp==1.8.0")
   • O_LAYER_ARN: This will be updated after creating the Lambda layer

3. API Gateway and Lambda Configuration:

   • P_API_STAGE: API Gateway stage name (default: dev)
   • P_FN_MEMORY: Lambda function memory in MB (default: 128)
   • P_FN_TIMEOUT: Lambda function timeout in seconds (default: 15)

Deployment Steps

1. Create the Lambda Layer:

   make layer

   After execution, copy the outLayer value and update the O_LAYER_ARN in etc/environment.sh.

2. Deploy the API Gateway and Lambda function:

   make apigw

   This will create the API Gateway and Lambda function, which will have the MCP dependencies layer attached.

Testing

1. After deployment, you'll receive an outApiEndpoint value.
2. Use the MCP Inspector tool to test the endpoint:
   • Enter the following URL in MCP Inspector: ${outApiEndpoint}/echo/mcp/

Make Commands

• make layer: Creates the Lambda layer with MCP dependencies
• make apigw: Deploys the API Gateway and Lambda function

Troubleshooting

If you encounter any issues:

1. Ensure all environment variables are properly set in etc/environment.sh
2. Verify AWS credentials are correctly configured
3. Check AWS CloudWatch logs for Lambda function errors
4. Ensure the S3 bucket specified in BUCKET exists and is accessible