Garance Buricatu

Posted on Nov 1 • Edited on Nov 4

How to Deploy Your Rig App on AWS Lambda: A Step-by-Step Guide

#rust #aws #llm #devops

TL;DR

A step-by-step walkthrough on deploying a simple AI Agent built with Rig, a fullstack agent framework, on AWS Lambda using the cargo lambda CLI.
Comparison of performance metrics (memory usage, execution time, and cold starts) with a similar deployed Agent built with LangChain.
Stats: Rig Agent on AWS Lmabda :
1. Low memory usage (26MB average)
2. Fast cold starts (90.9ms)
3. Consistent performance across memory configurations
Stats: LangChain Agent on AWS Lmabda:
1. Higher memory usage (112-130MB)
2. Slower cold starts (1,898.52ms)
3. Performance improves with more memory allocation

How to Deploy Your Rig App on AWS Lambda: A Step-by-Step Guide

Introduction

Welcome to the series Deploy Your Rig Application!
Apps built with Rig can vary in complexity across three core dimensions: LLM usage, knowledge bases for RAG, and the compute infrastructure where the application is deployed. In this series, we’ll explore how different combinations of these dimensions can be configured for production use.

Today, we’ll start with a simple Rig agent that uses the OpenAI model GPT-4-turbo, does not rely on a vector store (ie.: no RAGing), and will be deployed on AWS Lambda.

This blog will provide a step-by-step deployment guide for the simple Rig app, showcase performance metrics of the Rig app running on AWS Lambda, and compare these metrics with those of a LangChain app on the same platform.

💡 If you're new to Rig and want to start from the beginning or are looking for additional tutorials, check out our blog series.

Let’s dive in!

Prerequisites

Before we begin building, ensure you have the following:

A clone of the rig-entertainer-lambda crate (or your own Rig application).
An AWS account
An Open AI api key

AWS Lambda Quick Overview

You might deploy your Rust application on AWS lambda if it’s a task that can execute in under 15 mins or if your app is a REST API backend.

AWS 🤝 Rust

AWS Lambda supports Rust through the use of the OS-only runtime Amazon Linux 2023 (a lambda runtime) in conjunction with the Rust runtime client, a rust crate.

REST API backend

Use the lambda-http crate (from the runtime client) to write your function’s entrypoint.
Then, route traffic to your lambda via AWS API services like Api Gateway, App Sync, VPC lattice, etc ...
If your lambda handles multiple endpoints of your API, the crate axum facilitates the routing within the lambda.

Event based task (15 mins max.)

Your lambda function is invoked by some event with the event passed as the payload. For example, configure your S3 bucket to trigger the lambda function when a new object is added to the bucket. The function will receive the new object in the payload and can further process it.
Use the lambda_runtime crate with lambda_events (from the runtime client) to write your function’s entrypoint.
Then, invoke your function either via lambda invoke command or with integrated AWS triggers (ie. S3 UploadObject trigger).

For both cases, the crate tokio must also be added to your project as the lambda runtime client uses tokio to handle asynchronous calls.

Rig Entertainer Agent App 🤡

The crate rig-entertainer-lambda implements a simple Rust program that is executed via the lambda_runtime. It invokes a Rig agent using the OpenAI API, to entertain users with jokes. It is an event-based task that I will execute with the lambda invoke command.

The main takeaway here is that the app's Cargo.toml file must include the following dependencies:

rig-core (our rig crate)
lambda_runtime
tokio

Now let's deploy it!

There are many ways to deploy Rust lambdas to AWS. Some out of the box options include the AWS CLI, the cargo lambda CLI, the AWS SAM CLI, the AWS CDK, and more. You can also decide to create a Dockerfile for your app and use that container image in your Lambda function instead. See some useful examples here.

In this blog, we'll use the cargo lambda CLI option to deploy the code in rig-entertainer-rust from your local machine to an AWS lambda:

# Add your AWS credentials to my terminal
# Create an AWS Lambda function named ‘rig-entertainer’ with architecture x86_64.

function_name='rig-entertainer'

cd rig-entertainer-lambda
cargo lambda build --release # Can define different architectures here with --arm64 for example
cargo lambda deploy $function_name # Since the name of the crate is the same as the the lambda function name, no need to specify a binary file

Metrics on the cloud ☁️

Deployment package

This is the code configuration of the rig-entertainer function in AWS. The function’s code package (bundled code and dependencies required for lambda to run) includes the single rust binary called bootstrap, which is 3.2 MB.

Memory, CPU, and runtime

The image below gives metrics on memory usage and execution time of the function. Each row represents a single execution of the function. In yellow is the total memory used, in red is the amount of memory allocated, and in blue is the runtime.
Although the lambda has many configuration options for the memory ranging from 128MB to 1024MB, we can see that the average memory used by our app is 26MB.

Let's get more information on the metrics above by spamming the function and calculating averages. I invoked rig-entertainer 50 times for each memory configuration of 128MB, 256MB, 512MB, 1024MB using the power tuner tool and the result of those invocations are displayed in the chart below.

The x-axis is the memory allocation, and the y-axis is the average runtime over the 50 executions of rig-entertainer.

Q. We know that the function uses on average only 26MB per execution (which is less than the minimum memory allocation of 128MB) so why should we test higher memory configurations?

A. vCPUs are added to the lambda in proportion to memory so adding memory could still affect the performance.

However, we can see that adding memory to the function (and therefore adding computational power) does not affect its performance at all. Since the cost of a lambda execution is calculated in GB-seconds, we get the most efficient lambda for the lowest price!

Cold starts ❄️

Cold starts occur when the lambda function's execution environment needs to be booted up from scratch. This includes setting up the actual compute that the lambda function is running on, and downloading the lambda function code and dependencies in that environment.

Cold start latency doesn't affect all function executions because once the lambda environment has been setup, it will be reused by subsequent executions of the same lambda.

In the lambda cloudwatch logs, if a function execution requires a cold start, we see the Init Duration metric at the end of the execution.

For rig-entertainer, we can see that the average cold start time is 90.9ms:

Note that the function was affected by cold starts 9 times out of the 245 times it was executed, so 0.036% of the time.

Langchain Entertainer Agent App 🐍

I replicated the OpenAI entertainer agent using the langchain python library in this mini python app which I also deployed to AWS Lambda in a function called langchain-entertainer.

Let's compare the metrics outlined above.