Deploying a MCP Server on AWS with Terraform

What is MCP and Why Does It Matter?

MCP allows LLMs to seamlessly integrate with external services through standardised servers. Think of it as a universal adapter:

This interoperability means businesses can bridge AI models with live services safely and flexibly.

At Horaizon, our use case centred on customer data interaction, enabling an LLM to query, analyse, and provide insights in real time.

Our Architecture at a Glance

Here's how we built and deployed our serverless MCP solution:

Building the MCP Server

For local development, we leveraged FastMCP to quickly set up an MCP server.

For serverless deployment on AWS, however, we had to think about how to run a 'server-based' application in Lambda. This is where the AWS Lambda Web Adapter came in, which proxies incoming requests to the MCP server running inside a Lambda function.

Exposing the Endpoint

Once the Lambda was set up, we created an API Gateway which provided us with an endpoint from which we could route requests to the Lambda function in which our FastMCP server was running.

Terraform Automation

Instead of manual setup, our entire infrastructure is defined as code with Terraform, ensuring repeatability, scalability, and easy updates.

Integrating with LLMs

Our particular use case for building an MCP server involved interacting with customer data, so we wrote tools which allowed an integrating LLM to retrieve this data and provide insights on it. The integrating LLM was built on top of OpenAI's Responses API, as the Completions API does not currently support MCP tool calling.

Frontend Delivery

The integrating LLM was then exposed to the Angular frontend using a WebSocket API, allowing for long-running connections. We again made use of Lambda functions to host the integrating LLM, routing requests made to the WebSocket API to it.

Word of Advice

By default, the Lambda Web Adapter routes requests to the "/" path of your server. The FastMCP server URL is at /mcp/, so we had to use the AWS_LWA_READINESS_CHECK_PATH Lambda environment variable and set it to "/mcp/" so that requests did not return 404 Not Found responses.

The code is proprietary, so we won't be sharing it, but hopefully the above gives you a clear idea of how to go about setting up an MCP server on AWS with Terraform.

Standing on the Shoulders of Innovators

Our work builds on excellent explorations by:

Both served as inspiration and reference points as we refined our Terraform-based solution.

At Horaizon, we're not just exploring AI infrastructure, we're building practical, production-grade solutions that unlock new possibilities for businesses.