@noths/cloud-utils

Cloud Utilities

A collection of helpful Node.JS utility functions which are used across Lambda (and other) serverless functions.

Secrets

Wraps function execution with encrypted secrets from AWS SSM Parameter Store using a specific key, provided that the executing IAM Role has sufficient privileges to do so.

import { withParameters } from '@noths/cloud-utils';

const SECRET_KEY = '/path/to/ssm/encrypted/secret';

const ALIAS = 'SUPER_SECRET_KEY';

const myFn = async ({ [ALIAS]: key }, a, b) => {
  return thirdPartyApi(key).someOperation(a, b);
};

export default withParameters({ [ALIAS]: SECRET_KEY })(myFn);

Elsewhere in the application, this function can be consumed as:

import myFn from './some-file';

const handler = async (a, b, ...other) => {
  const { result } = await myFn(a, b);
  return result;
};

---

Errors

Provides a helpful utility for optionally wrapping low-level, native error objects from libraries with application errors which can be:

• Serialized and surfaced to consumer applications.
• Filtered inside logs using JSONPath to provide custom application error metrics.

import { withProperties } from '@noths/cloud-utils/tools/errors';

export const FOOBAR_ERROR = 'FoobarError';

const errors = {
  ...(withProperties(FOOBAR_ERROR, { statusCode: 400, message: 'A foobar error occurred' })),
};

export default errors;

When you need to throw an error of this type inside your application, you can instantiate it like so:

import Errors, { FOOBAR_ERROR } from './errors';

const { [FOOBAR_ERROR]: LogicalError } = Errors;

const fn = (cb) => {
  someOperation((err, data) => {
    if (err) {
      throw new LogicalError('overrides default message', err);
    } else {
      cb(data);
    }
  })
};

---

Logger

Simple logger for serializing objects and application errors into JSON lines for inspection and JSONPath filtering.

import Logger from '@noths/cloud-utils/tools/logger';

const TIME_TAKEN = 'ExecutionTimeTaken';

const reporter = (time) => ({ time, type: TIME_TAKEN });

const handler = async () => {
  const start = +new Date();
  const data = await processor();
  const end = +new Date();
  Logger.info(reporter(end - start));
  return data;
};

There are two environment variables you can set, in-order to control the logger:

• LOG_LEVEL - The level of logging to produce output for.

---

Responders

HTTP Responders wrap response objects from Lambda Proxy functions (or any other mechanism), enabling the easy serialization of Javascript objects whether it is a success or failure.

import { success, failure } from '@noths/cloud-utils/tools/responders';

// Object containing security HTTP headers & CORS
import headers from './headers';

export const handler = async (event, context, cb) => {
  try {
    const result = await processor(event);
    const response = success({ code: 201, headers, body: result });
    cb(null, response);
  } catch (err) {
    if (err.statusCode) {
      // application error
      cb(null, failure(event, err));
    } else {
      // native error
      cb(err);
    }
  }
};