saucepoint / rust-lambda-api

Template repo for quickly creating an HTTP API with Rust hosted on AWS Lambda

rust-lambda-api

🦀 Create HTTP APIs with Rust, hosted on AWS Lambda (serverless compute) 🦀

Lightweight, fast, and preorganized

The template includes examples for routing, query parameters, request bodies, and response serialization, which are absent from cargo-lambda

All of the AWS infrastructure is created & handled with Terraform. What are you waiting for, anon?

---

Setup & Dependencies

1. Configure AWS CLI

2. Install Rust & cargo-lambda

   • cargo install cargo-lambda

3. Install terraform

4. Prepare an initial .zip for Terraform to upload to AWS

   cd lambda-api/
   cargo lambda build --output-format zip
   cd ..

5. Use terraform to spin up AWS infrastructure

   cd terraform/
   terraform init
   terraform apply
   // read the changes reported by terraform
   // type yes and hit Enter
   // Successful infra deployment will return:
   // Apply complete! Resources: 3 added, 0 changed, 0 destroyed.
   

   Note: The initial creation of the Lambda will take up to 1 min to process. If you attempt a cargo lambda deploy shortly after resource-creation, it will fail if the Lambda has an in-progress update

Configuration

Adding Routes:

1. Create a new file such as lambda-api/src/api/foo.rs

   • Add GET/POST handlers, Request/Response structs, similar to src/api/hello.rs

2. Register the route in lambda-api/src/main.rs similar to this

   "/foo" => {
       match method {
           Method::POST => api::foo::post(event),
           Method::GET => api::foo::get(event),
           _ => api::errors::handle_405(),
       }
   }

Rename the function:

1. lambda-api/Cargo.toml

   • name = "lambda-api" --> NEW_FUNCTION_NAME

2. terraform/main.tf

   • function_name = "lambda-api" --> NEW_FUNCTION_NAME
   • filename = "../lambda-api/target/lambda/lambda-api/bootstrap.zip" --> "../lambda-api/target/lambda/NEW_FUNCTION_NAME/bootstrap.zip"

3. Apply changes

   cd lambda-api/
   cargo lambda build
   cd ../terraform/
   terraform apply

You can use terraform or AWS console to attach additional infrastructure

Local Development

In a new terminal:

cd lambda-api/

cargo lambda watch

Testing:

The base URL will be 127.0.0.1:9000/lambda-url/lambda-api

GET 127.0.0.1:9000/lambda-url/lambda-api/hello?name=saucepoint&number=100

POST 127.0.0.1:9000/lambda-url/lambda-api/hello
// with raw JSON body:
{
    "name": "saucepoint",
    "number": 100
}

Note: when deployed to Lambda, your route will not have /lambda-url/lambda-api prefix:

https://RANDOM_HASH.lambda-url.REGION.on.aws/hello

Deploying

Please see cargo-lambda for additional flags (such as environment variables)

This is my preferred deployment call:

Get your IAM Role's ARN from the AWS web console

cargo lambda build --release && cargo lambda deploy --enable-function-url --iam-role arn:aws:iam::<AWS_ACCOUNT_NUMBER>:role/rust-lambda-api 

---

Disclaimer

This template repo is intended for hobbyists and experiments. The following bits will need to be modified & enhanced before it can be considered production-ready:

🚩 Tests - this repo totally lacks automated tests

🚩 Modularized Terraform - the current files will collide with resources of the same name. The files should be better organized & more configurable such that it can tap into existing infrastructure (VPCs)

🚩 AWS API Gateway Trigger - Typical Lambda REST APIs sit behind API Gateway. It didn't stop me from getting this prototype functional, so I didn't really bother

🚩 API authentication - this repo offers no examples around auth-required APIs

Feel free to submit PRs!

---

I'm tinkering outside of my 9-5, with plans to launch something, eventually

Find me on twitter @saucepoint