GREsau / example-rocket-lamb-api

🚀 Example Rocket Lamb API 🐑

A simple web API written using Rocket, with two binaries:

• main, a normal application which you can run locally for testing
• lambda, written to be run as an AWS Lambda function, using Rocket Lamb

It has two endpoints defined:

• / (the root path) - returns Hello world as a plaintext response
• /rocket - returns a PNG image

Deploying to AWS Lambda

Deployment can be done using AWS CloudFormation using the Serverless Application Model. The required CloudFormation template is already set up in template.yaml.

Requirements:

• Docker
• AWS CLI
• An existing S3 bucket

# Builds the lambda binary in a Docker container and outputs the packaged zip file
docker-compose run --rm build

S3_BUCKET=my-s3-bucket-name
# Choose any name you like for the CloudFormation stack
STACK_NAME=my-rocket-api

# Uploads the CloudFormation template and zipped binary to S3
aws cloudformation package --template-file template.yaml --output-template-file packaged.yaml --s3-bucket $S3_BUCKET

# Deploys the CloudFormation stack
aws cloudformation deploy --template-file packaged.yaml --capabilities CAPABILITY_IAM --stack-name $STACK_NAME

# Outputs the API Gateway URL that you can use to call your API
aws cloudformation describe-stacks --query "Stacks[0].Outputs" --stack-name $STACK_NAME

Testing Locally

The easiest way of running the application locally is just with cargo run, which will run main.rs. This configures and launches a bog-standard Rocket server, without using Rocket Lamb.

Another way is to use the AWS SAM CLI, which can be used to spin up a fake lambda environment in Docker with a mock API Gateway. While more of a hassle to run, this will also test both the CloudFormation configuration in template.yaml, and the application's integration with Lambda and API Gateway. To run the app using the SAM CLI:

docker-compose run --rm build

sam local start-api