Serverless Middleware

A helper for writing APIs using AWS Lambda functions.

Features

• Dependency injection for easy unit testing.
• Pretty JSON error output, with status codes automatically determined based on error message.
• Easy access to query strings and JSON body properties.
• Serverless warmup plugin support.
• OpenTelemetry support and additional span attributes, for use with opentelemetry-lambda.

Installation

yarn add @includable/serverless-middleware

Example usage

import { middleware, auth } from "@includable/serverless-middleware";

const dependencies = {
  // dependencies for the dependency injector
};

export const app = async (
  { query, path, body },
  { currentUser /* dependences */ },
) => {
  // if `auth` is included in the second param of `middleware`, currentUser
  // will be an object in the form of `{ id, groups, email, ... }`

  // your business logic goes here

  return {
    success: true,
    text: "Hello, world!",
  };
};

export const handler = middleware(app, [auth]).register(dependencies);

Options

Warmup support

Out of the box this middleware setup supports the serverless-plugin-warmup serverless plugin.

Simply install the serverless plugin, no other changes to your code necessary. The middleware will automatically prevent code execution on warmup requests.

OpenTelemetry span enrichment

If an active OpenTelemetry span is detected, event and response properties will automatically be added.