Introduction

Welcome to Holp!

What is Holp?

Holp is a library that simplifies common AWS Lambda patterns, reducing boilerplate code and promoting best practices. It facilitates consistent error handling and wraps our handler using a higher-order function approach. The name "holp" stands for "Higher-Order Lambda Proxies" drawing inspiration from the concept of Higher-Order Components (HOC) in React. Think of holp as a HOC for Lambda handlers, streamlining response management and error handling for more efficient and consistent serverless development.

A quick example

import { APIGatewayEvent } from "aws-lambda";
import { withApiGateway, ApiGatewayParsedEvent } from "holp";
import { BadRequestError } from "holp/errors";
import logger from 'my-logging-library';
 
interface MyEvent extends ApiGatewayParsedEvent {
  body: {
    someParam: string,
  },
  queryStringParameters: {
    someQueryParam: string,
  }
};
 
export const myLambdaFunction = async (event: MyEvent) => {
  const someParam = event.body.someParam;
  const someQueryParam = event.queryStringParameters.someQueryParam;
  logger.info('Some insightful log message.')
  const result = await someAsyncTask(someParam, someQueryParam);
  if (result.length === 0) {
    throw new BadRequestError("Result does not exist.");
  }
  return { result }
}
 
export const Handler = withAPIGateway(myLambdaFunction, { logger });

Why?

One of the main strengths of serverless and AWS Lambda is that, from a developer perspective, your focus is mostly shifted toward implementing business logic. Anyway, when you are writing a handler, you still have to deal with some common technical concerns outside business logic, like input parsing and validation, output serialization, error handling, etc. Very often, all this necessary code ends up polluting the pure business logic code in your handlers, making the code harder to read and to maintain. Holp aims to solve this problem in a simple and elegant way, by providing a set of opinionated tools that can be used to wrap your handlers, so that you can focus on the business logic and let Holp take care of the rest.