Deploying a Rust MCP Server to Amazon Lambda with Gemini CLI

The rmcp crate and standard Rust libraries are used to build a basic MCP Server in Rust. This MCP...

tags: rust,aiagent,aws,awslambda Series: Rust

The rmcp crate and standard Rust libraries are used to build a basic MCP Server in Rust. This MCP Server is then built and deployed to AWS Lambda and validated locally with Gemini CLI.

Even More MCP Demos?

MCP is the Sham-wow of the AI-Verse.

Why not just use Python?

Python has traditionally been the main coding language for ML and AI tools. One of the strengths of the MCP protocol is that the actual implementation details are independent of the development language. The reality is that not every project is coded in Python- and MCP allows you to use the latest AI appt roaches with other coding languages.

What is this Tutorial Trying to Do?

Building on previous tutorials, the goal is to extend a Rust MCP server with basic support for deployment to AWS.

What is Rust?

Rust is a high performance, memory safe, compiled language:

Rust

Rust provides memory safe operations beyond C/C++ and also can provide exceptional performance gains as it is compiled directly to native binaries.

So is this the Real Deal (tm)?

So what is different about this lab compared to all the others out there?

This is one of the first deep dives into deploying a Rust based MCP server hosted on AWS. The Amazon Fargate service was targeted for ease of setup and deployment.

Rust Setup

Instructions to install Rust are available here:

Getting started

For a Linux like environment the command looks like this:

curl — proto ‘=https’ — tlsv1.2 -sSf https://sh.rustup.rs | sh

Rust also depends on a working C compiler and OpenSSL setup. For a Debian 12 system — install the basic tools for development:

sudo apt install build-essential
sudo apt install libssl-dev
sudo apt install pkg-config
sudo apt-get install libudev-dev
sudo apt install make
sudo apt install git

Gemini CLI

If not pre-installed you can download the Gemini CLI to interact with the source files and provide real-time assistance:

npm install -g @google/gemini-cli

Testing the Gemini CLI Environment

Once you have all the tools and the correct Node.js version in place- you can test the startup of Gemini CLI. You will need to authenticate with a Key or your Google Account:

▝▜▄ Gemini CLI v0.33.1
    ▝▜▄
   ▗▟▀ Logged in with Google /auth
  ▝▀ Gemini Code Assist Standard /upgrade no sandbox (see /docs) /model Auto (Gemini 3) | 239.8 MB

AWS CLI

The AWS CLI provides a command line tool to directly access AWS services from your current environment. Full details on the CLI are available here:

Install Docker, AWS CLI, and the Lightsail Control plugin for containers

You can version check the tool after installation:

xbill@penguin:~/gemini-cli-aws/mcp-lightsai-rust-aws$ aws --version
aws-cli/2.34.43 Python/3.14.4 Linux/6.6.99-09128-g14e87a8a9b71 exe/x86_64.debian.12

Amazon Lambda

AWS Lambda is a serverless, event-driven compute service that enables users to run code without provisioning or managing servers. With Lambda, developers can focus solely on their code (functions), while AWS handles all underlying infrastructure management, including capacity provisioning, automatic scaling, and operating system maintenance.

Full details are here:

Serverless Computing Service - Free AWS Lambda - AWS

Setup the Basic Environment

At this point you should have a working Rust environment and a working Gemini CLI installation. All of the relevant code examples and documentation is available in GitHub.

The next step is to clone the GitHub repository to your local environment:

cd ~
git clone https://github.com/xbill9/gemini-cli-aws

Then run init.sh from the cloned directory.

The script will attempt to determine your shell environment and set the correct variables:

source init.sh

If your session times out or you need to re-authenticate- you can run the set_env.sh script to reset your environment variables:

source set_env.sh

Variables like PROJECT_ID need to be setup for use in the various build scripts- so the set_env script can be used to reset the environment if you time-out.

Refresh the AWS credentials:

xbill@penguin:~/gemini-cli-aws/mcp-lambda-rust-aws$ aws login --remote
Browser will not be automatically opened.

xbill@penguin:~/gemini-cli-aws/mcp-lambda-rust-aws$ source save-aws-creds.sh 
Exporting AWS credentials...
Successfully saved credentials to .aws_creds
The Makefile will now automatically use these for deployments.

Finally install the packages and dependencies:

~/gemini-cli-aws/mcp-lambda-rust-aws

Build The Rust MCP Server

Some background information on building and configuring a Rust MCP server is here:

Building a Secure HTTP Transport MCP Server with Rust, and Gemini CLI

The mcp-lambda-rust-aws subdirectory has the complete Rust MCP server in one subdirectory.

Minimal System Information Tool Build

The first step is to build the basic tool directly with Rust. This allows the tool to be debugged and tested locally before adding the MCP layer.

First build the tool locally:

xbill@penguin:~/gemini-cli-aws/mcp-lambda-rust-aws$ make
Building the Rust project...
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.33s
xbill@penguin:~/gemini-cli-aws/mcp-lambda-rust-aws$ 

then lint check the code:

xbill@penguin:~/gemini-cli-aws/mcp-lambda-rust-aws$ make lint
Linting code...
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.22s
xbill@penguin:~/gemini-cli-aws/mcp-lambda-rust-aws$ 

and run local tests:

xbill@penguin:~/gemini-cli-aws/mcp-lambda-rust-aws$ make test
Running tests...
    Finished `test` profile [unoptimized + debuginfo] target(s) in 0.30s
     Running unittests src/main.rs (target/debug/deps/mcp_ebs_rust_aws-0a683fe2cbff5a44)

running 2 tests
test tests::test_greeting ... ok
test tests::test_greet ... ok

test result: ok. 2 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

xbill@penguin:~/gemini-cli-aws/mcp-lambda-rust-aws$

The last step is to build the production version:

xbill@penguin:~/gemini-cli-aws/mcp-lambda-rust-aws$ make release
Building Release...
    Finished `release` profile [optimized] target(s) in 0.24s
xbill@penguin:~/gemini-cli-aws/mcp-lambda-rust-aws$ 

The MCP server can be started locally:

xbill@penguin:~/gemini-cli-aws/mcp-lambda-rust-aws$ make start
Building Release...
    Finished `release` profile [optimized] target(s) in 0.07s
Starting the MCP server...
Server started with PID 17599

The MCP tool can then be tested:

/mcp list
> mcp_local-rust_greeting local

╭────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╮
│ Action Required │
│ │
│ ? greeting (local-rust MCP Server) {"message":"local"} │
│ │
│ MCP Server: local-rust │
│ Tool: greeting │
│ │
│ MCP Tool Details: │
│ (press Ctrl+O to expand MCP tool details) │
│ Allow execution of MCP tool "greeting" from server "local-rust"? │
│ │
│ 1. Allow once │
│ 2. Allow tool for this session │
│ 3. Allow all server tools for this session │
│ ● 4. Allow tool for all future sessions ~/.gemini/policies/auto-saved.toml │
│ 5. No, suggest changes (esc) │
╰────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╯

✦ The mcp_local-rust_greeting tool was executed with the message "local", returning:
  "Hello World MCP! local"

Deploy To AWS Lambda

A basic Dockerfile is used to build an image for deployment:

xbill@penguin:~/gemini-cli-aws/mcp-lambda-rust-aws$ make deploy
Ensuring IAM role McpLambdaExecutionRole exists...
Ensuring AWSLambdaBasicExecutionRole is attached...
Checking if ECR repository exists...
Logging in to Amazon ECR...

Check the Status:

xbill@penguin:~/gemini-cli-aws/mcp-lambda-rust-aws$ make status
-------------------------------------------------------------------
| GetFunction |
+-------------------------------+-----------------------+---------+
| LastModified | Name | Status |
+-------------------------------+-----------------------+---------+
| 2026-05-13T01:55:43.000+0000 | mcp-lambda-rust-aws | Active |
+-------------------------------+-----------------------+---------+
xbill@penguin:~/gemini-cli-aws/mcp-lambda-rust-aws$ 

Get the Endpoint:

xbill@penguin:~/gemini-cli-aws/mcp-lambda-rust-aws$ make endpoint
https://vry3auzzqvt7jigvdpy4xnkryq0fukjw.lambda-url.us-east-1.on.aws/

Check Gemini MCP settings:

{
  "mcpServers": {
    "aws-lambda-rust": {
      "httpUrl": "https://vry3auzzqvt7jigvdpy4xnkryq0fukjw.lambda-url.us-east-1.on.aws/mcp"
    },
    "local-rust": {
      "httpUrl": "http://127.0.0.1:8080/mcp"
    }
  }
}

The service will be visible on the AWS console:

Final Test

Start up Gemini CLI and check the MCP server status:

🟢 aws-lambda-rust - Ready (1 tool)
  Tools:
  - mcp_aws-lambda-rust_greeting

                                                                                                                                                     
 > mcp_aws-lambda-rust_greeting Hello Lambda!

╭───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╮
│ ✓ greeting (aws-lambda-rust MCP Server) {"message":"Hello Lambda!"} │
│ │
│ Hello World MCP! Hello Lambda! │
╰───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╯

✦ Hello World MCP! Hello Lambda!

Summary

A complete HTTP transport MCP server was built using Rust. This application was tested locally with Gemini CLI. Then, the entire solution was deployed to AWS Lambda. The remote MCP server was validated with Gemini CLI locally.