@genie-solutions/lambda-toolbelt

Genie Lambda Toolbelt

Set of reusable tools to make writing new Lambda functions a breeze.

Sample Usage

import { applyMiddleware, httpHandler, withJSONBody, HTTPEvent, HTTPContext } from 'genie-lambda-toolbelt';

const myHelloWorldFunction = async (event: HTTPEvent, context: HTTPContext): Promise<object> => {
  const { genie: { body } } = context;
  return {
    message: `Hello, ${body.name}`,
  };
};

export default applyMiddleware(httpHandler, withJSONBody)(myHelloWorldFunction);

withJWTPayload

Automatically verifies and parses the payload of a JWT token being provided via a HTTP header.

Example:

import { createParameterStore, applyMiddleware, httpHandler, withJWTPayload } from 'genie-lambda-toolbelt';

const mySuperSecretFunction = async (event: HTTPEvent, context: HTTPContext): Promise<object> => {
  const { userId, tenantId, roleId } = context.genie.jwt.role;
  return Promise.resolve('Oll Korrect (yep, that is what OK stands for)');
};

const parameterStore = createParameterStore();
const getPublicKey = () => parameterStore('JWT_PUBLIC_KEY');

export default applyMiddleware(
  httpHandler,
  withJWTPayload({
    getPublicKey,
    algorithm: 'RS256',
    headerName: 'X-GENIE-ROLES',
    payloadKey: 'role',
  }),
)(mySuperSecretFunction);

withParameters

Automatically add parameters into genie context and validate any required params.

Example:

import {
  applyMiddleware,
  httpHandler,
  withJSONBody,
  withParameters,
  HTTPEvent,
  HTTPContext
} from 'genie-lambda-toolbelt';

// These interfaces should be in type.ts, here is just quick example
interface MyPathParamsContext {
  pathParameters: {
    pathParam1: string;
  }
}

interface MyQueryStringParamsContext {
  queryStringParameters: {
    qsParam1: string;
    qsParam2: string;
  }
}

interface MyBodyContext {
  body: {
    bodyParam1: string;
    bodyParam2: number;
  }
}

type MyCustomContext = HTTPContext<MyBodyContext & MyPathParamsContext & MyQueryStringParamsContext>;

const mySuperSweetFunction = async (event: HTTPEvent, context: MyCustomContext): Promise<object> => {
  const genie = context.genie;
  const { pathParam1 } = genie.pathParameters;
  const { qsParam1, qsParam2 } = genie.queryStringParameters;
  const { bodyParam1, bodyParam2 } = genie.body;

  return {};
};

export default applyMiddleware(
  httpHandler,
  withJSONBody,
  withParameters({
    // These fields should be defined when actually required
    requiredPathParams: ['pathParam1'],
    requiredJsonBodyParams: ['bodyParam1', 'bodyParam2'],
    requiredQueryStringParams: ['qsParam1', 'qsParam2'],
  }),
)(mySuperSweetFunction);

withClientId

Automatically validate required clientId and assign to genie

Example:

import { applyMiddleware, httpHandler, withClientId, withJSONBody, HTTPContext, ClientIdContext } from 'genie-lambda-toolbelt';

// These interfaces should be in type.ts, here is just quick example
type MyCustomContext = HTTPContext<ClientIdContext>;

const mySuperSweetFunction = async (event: HTTPEvent, context: MyCustomContext): Promise<object> => {
  const { genie: { clientId } } = event;

  return {};
};

export default applyMiddleware(
  httpHandler,
  withJSONBody,
  withClientId,
)(mySuperSweetFunction);

HOW TO EXTEND HTTPContext

Many times you will want to custom your own HTTPContext and extends it with many other available Context such as ClientIdContext, JwtContext To do this, you can leverage HTTPContext<T1 & T2 & ... & TN> to mix n-contexts into One Final Interface

Example:

import {
  applyMiddleware,
  httpHandler,
  withClientId,
  withJSONBody,
  HTTPEvent,
  HTTPContext,
  JwtContext,
  ClientIdContext
} from 'genie-lambda-toolbelt';

interface MyBodyContext {
  body: {
    bodyParam1: string;
    bodyParam2: number;
  }
}

type MyCustomContext = HTTPContext<MyBodyContext & ClientIdContext & JwtContext>;

const mySuperSweetFunction = async (event: HTTPEvent, context: MyCustomContext): Promise<object> => {
  // Then you can use your Customized Context with the combined structure
  const genie = context.genie;
  const { bodyParam1, bodyParam2 } = genie.body;
  const { roles } = genie.jwt;
  const { clientId } = genie;

  return {};
};

export default applyMiddleware(
  httpHandler,
  withJSONBody,
  withClientId,
)(mySuperSweetFunction);