Microservice Utilities

Utilities supporting authorization, request logging and other often required parts of microservices.

Using this library

Install the library.

npm install microservice-utilities

Request Logger

Logger which takes care of truncating Bearer tokens and safe JSON stringification. While it logs to console by default, it also supports a custom logging function. By default it is also configured to extend the Error object using error-object-polyfill.js, which enables stringification of Error objects to JSON. That enables the error message and stack traces to appear in logs.

const { RequestLogger } = require('microservice-utilities');
const defaultConfiguration = { logFunction: console.log, extendErrorObjects: true };

let requestLogger = new RequestLogger(defaultConfiguration);
requestLogger.log({ title: 'Message title', level: 'WARN', error: 'Error'});

Authorizer

Authorizer to be used with AWS API Gateway. It also adds the caller's JWT to the API Gateway authorizer request context.

Example usage with OpenAPI Factory.

npm install openapi-factory

const Api = require('openapi-factory');
const { Authorizer, RequestLogger } = require('microservice-utilities');
const configuration = {
  // URL to get jwk keys to verify token
  jwkKeyListUrl: 'https://example.com/.well-known/jwks.json',
  // custom resolver that returns additional context form the AWS Lambda authorizer
  authorizerContextResolver: (identity, token) => ({
    authorizerContextResult: 'my context'
  }),
  // optional AWS API Gateway usage plan
  // See details at https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-api-usage-plans.html
  usagePlan: 'usage-plan-id',
  // jwtVerifyOptions that are passed into jsonwebtoken
  // see https://github.com/auth0/node-jsonwebtoken#jwtverifytoken-secretorpublickey-options-callback
  // defaults to { algorithms: ['RS256'] }
  jwtVerifyOptions: { algorithms: ['RS256'], audience: 'my-audience' }
};

let requestLogger = new RequestLogger();
let authorizer = new Authorizer(msg => requestLogger.log(msg), configuration);
let api = new Api();

api.setAuthorizer(async request => {
  return await authorizer.getPolicy(request);
});

api.get('/v1/item', async request => {
  // JWT added by authorizer
  let jwt = request.requestContext.authorizer.jwt;

  // JWT included in the request will be automatically truncated by the RequestLogger
  requestLogger.log({ title: 'GET /v1/item', level: 'INFO', request: request });
});

Service Token Provider

Token provider which can be used to retrieve service access tokens. These can be used to call other services on behalf of the clientId specified in the configuration. It uses AWS KMS to decrypt the client secret.

const axios = require('axios');
const { ServiceTokenProvider } = require('microservice-utilities');
const configuration = {
  clientId: 'CLIENT_ID',
  encryptedClientSecret: 'BASE64_KMS_ENCRYPTED_CLIENT_SECRET',
  audience: 'https://example.com/',
  tokenEndpoint: 'https://example.com/oauth/token'
};

let kmsClient = new aws.KMS({ region: 'eu-west-1' });
let serviceTokenProvider = new ServiceTokenProvider(axios.create(), kmsClient, configuration);

// recommended way to retrieve token (utilizes caching and takes care of token expiration)
let accessToken = await serviceTokenProvider.getToken();

// or bypass caching and get new token
accessToken = await serviceTokenProvider.getTokenWithoutCache();

Platform Client

Http client wrapper providing convenient get, post, put methods with extended logging. It supports custom Bearer token resolvers and uses them to set the Authorization header properly.

const { PlatformClient, RequestLogger } = require('microservice-utilities');

let requestLogger = new RequestLogger();
let tokenResolver = () => "exampleAccessToken";
let platformClient = new PlatformClient(msg => requestLogger.log(msg), tokenResolver);

let headers = {};
let dataObject = { exampleProperty: 'exampleValue' };

let getResponse = await platformClient.get('VALID_URL', headers);
let postResponse = await platformClient.post('VALID_URL', dataObject, headers);
let putResponse = await platformClient.put('VALID_URL', dataObject, headers);

If you wish to override Http client defaults and/or add your own interceptors, provide an options object containing an axios client as the third parameter when creating PlatformClient.

const axios = require('axios');
let axiosClient = axios.create({ timeout: 3000 });
new PlatformClient(msg => requestLogger.log(msg), tokenResolver, { client: axiosClient });

Contribution

We value your input as part of direct feedback to us, by filing issues, or preferably by directly contributing improvements:

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