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;
};

Tracing

Wraps modules & functions, providing AWS XRay tracing for trace execution. You may also provide a recognizable name for the module to be traced, in addition to custom metadata, annotations and captured functions as subsegments.

Note, functions wrapped with captureFunc or captureFuncSync should have a withTracing higher in their call stack; otherwise XRay will throw an error, as no namespace, segment or context has been configured.

Async module tracing with

import { captureFunc } from '@aerofer/utils/tools/tracing';
import someRemoteOperation from 'some-other-module';

const OPERATION = 'Some Remote Operation';

const metadata = {
  version: '0.0.1',
};

// capture arguments and add as annotations
const capture = (a, b) => ({ a, b });

const handler = async (a, b) => {
  const { body } = await someRemoteOperation(a, b);
  return body;
}

export default captureFunc(OPERATION, { metadata, capture })(handler);

Runtime sync tracing with annotations

import { captureFuncSync } from '@aerofer/utils/tools/tracing';
import captureSync from 'some-other-module';

const CAPTURE = 'Capture';

const handler = (customerId, amount) => {
  const annotations = { customerId };
  const capture = captureFuncSync(CAPTURE, { annotations })(captureSync);
  return capture(customerId, amount);
};

export default handler;

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);
    }
  }
};