Moesif AWS Lambda Middleware for Node.js documentation

by Moesif, the API analytics and API monetization platform.

With Moesif Node.js middleware for AWS Lambda, you can automatically log API calls and send them to Moesif for API analytics and monitoring. This middleware allows you to integrate Moesif's API analytics and API monetization features into your Node.js applications with minimal configuration.

If you're new to Moesif, see our Getting Started resources to quickly get up and running.

Who This Middleware is For

We've designed Moesif Node.js middleware for AWS Lambda for APIs that you host on AWS Lambda using Amazon API Gateway or Application Load Balancer as a trigger. The middleware works with REST APIs, GraphQL APIs (such as with apollo-server-lambda), and more.

If you're running a Node.js framework like Express.js on AWS Lambda and prefer to not have any AWS-specific dependencies, Moesif also has a Node.js middleware available. The Node.js middleware supports all Node.js frameworks, including Express.js. However, the Node.js middleware doesn't capture Lambda-specific context like trade ID.

Prerequisites

Before using this middleware, make sure you have the following:

• An active Moesif account
• A Moesif Application ID

Get Your Moesif Application ID

After you log into Moesif Portal, you can get your Moesif Application ID during the onboarding steps. You can always access the Application ID any time by following these steps from Moesif Portal after logging in:

1. Select the account icon to bring up the settings menu.
2. Select Installation or API Keys.
3. Copy your Moesif Application ID from the Collector Application ID field.

Install the middleware

In your project directory, install the middleware as a project dependency:

npm install --save moesif-aws-lambda

Configure the Middleware

See the available configuration options to learn how to configure the middleware for your use case.

How to use

1. Import the Module and Initialize

// Import Modules
'use strict'
const moesif = require('moesif-aws-lambda');

const moesifOptions = {
    applicationId: 'YOUR_MOESIF_APPLICATION_ID',

    identifyUser: function (event, context) {
        return event.requestContext.identity.cognitoIdentityId
    },
    identifyCompany: function (event, context) {
        return '5678'
    }
};

exports.handler = function (event, context, callback) {
    callback(null, {
        statusCode: '200',
        body: JSON.stringify({key: 'hello world'}),
        headers: {
            'Content-Type': 'application/json',
        },
    });
};

exports.handler = moesif(moesifOptions, exports.handler);

Replace YOUR_MOESIF_APPLICATION_ID with your Moesif Application ID.

Depends on the version of Node.js, you can also import directly:

import moesif from 'moesif-aws-lambda'

If you are using ECMAScript modules (ES modules) or later version of ES modules, try the following method:

const moesifImportWrapper = await import('moesif-aws-lambda');
const moesif = moesifImportWrapper.default;

2. Enter Your Moesif Application ID

The middleware expects your Moesif Application ID in the applicationId key of the Moesif initialization options object.

For instructions on how to obtain your Application ID, see Get your Moesif Application ID.

You can hardcode your Moesif Application ID value in applicationId. But we highly recommend that you use a more secure option like environment variables to store your Application ID. If you set the environment variable as MOESIF_APPLICATION_ID, Moesif automatically picks it up without you having to explicitly specify it in the applicationId key.

3. Call Your API

Finally, grab the URL to your API Gateway or Application Load Balancer and make some HTTP requests using a tool like Postman or cURL.

In order for your events to log to Moesif, you must test using the Amazon API Gateway trigger. Do not invoke your Lambda directly using AWS Console as the payload won't contain a valid HTTP payload.

Troubleshoot

For a general troubleshooting guide that can help you solve common problems, see Server Troubleshooting Guide.

Other troubleshooting supports:

• FAQ
• Moesif support email

Repository Structure

.
├── app.js
├── images/
├── lib/
├── LICENSE
├── package.json
├── package-lock.json
├── README.md
└── tests/

These are the most important files:

• lib/index.js: the middleware library
• app.js: sample AWS Lambda function using the middleware

Configuration Options

The following sections describe the available configuration options for this middleware. You can set these options in the Moesif initialization options object. See the sample AWS Lambda middleware function code for an example.

logBody

Data type	Default
Boolean	true

Whether to log request and response body to Moesif.

identifyUser

Data type	Parameters	Return type
Function	(event, context)	String

A function that takes AWS lambda event and context objects as arguments and returns a user ID. This allows Moesif to attribute API requests to individual unique users so you can understand who is calling your API. You can use this simultaneously with identifyCompany to track both individual customers and the companies they are a part of.

options.identifyUser = function (event, context) {
  // your code here, must return a string
  return event.requestContext.identity.cognitoIdentityId
}

identifyCompany

Data type	Parameters	Return type
Function	(event, context)	String

A function that takes AWS lambda event and context objects as arguments and returns a company ID. If you have a B2B business, this allows Moesif to attribute API requests to specific companies or organizations so you can understand which accounts are calling your API. You can use this simultaneously with identifyUser to track both individual customers and the companies they are a part of.

options.identifyCompany = function (event, context) {
  // your code here, must return a string
  return '5678'
}

getSessionToken

Data type	Parameters	Return type
Function	(event, context)	String

A function that takes AWS lambda event and context objects as arguments and returns a session token such as an API key.

options.getSessionToken = function (event, context) {
  // your code here, must return a string.
  return event.headers['Authorization'];
}

getApiVersion

Data type	Parameters	Return type
Function	(event, context)	String

A function that takes AWS lambda event and context objects as arguments and returns a string to tag requests with a specific version of your API.

options.getApiVersion = function (event, context) {
  // your code here. must return a string.
  return '1.0.5'
}

getMetadata

Data type	Parameters	Return type
Function	(event, context)	Object

A function that takes AWS lambda event and context objects as arguments and returns an object.

This function allows you to add custom metadata that Moesif can associate with the request. The metadata must be a simple JavaScript object that can be converted to JSON.

For example, you may want to save a virtual machine instance ID, a trace ID, or a tenant ID with the request.

options.getMetadata = function (event, context)  {
  // your code here:
  return {
    foo: 'custom data',
    bar: 'another custom data'
  };
}

skip

Data type	Parameters	Return type
Function	(event, context)	Boolean

A function that takes AWS lambda event and context objects as arguments and returns true if you want to skip the event. Skipping an event means Moesif doesn't log the event.

The following example skips requests to the root path /:

options.skip = function (event, context) {
  // your code here. must return a boolean.
  if (event.path === '/') {
    // Skip probes to home page.
    return true;
  }
  return false
}

maskContent

Data type	Parameters	Return type
Function	(MoesifEventModel)	MoesifEventModel

A function that takes the final Moesif event model, rather than the AWS lambda event or context objects, as an argument before the middleware sends the event model object to Moesif.

With maskContent, you can make modifications to headers or body such as removing certain header or body fields.

options.maskContent = function(moesifEvent) {
  // remove any field that you don't want to be sent to Moesif.
  return moesifEvent;
}

Moesif's event model format looks like this:

{
  "request": {
    "time": "2019-08-08T04:45:42.914",
    "uri": "https://api.acmeinc.com/items/83738/reviews/",
    "verb": "POST",
    "api_version": "1.1.0",
    "ip_address": "61.48.220.123",
    "headers": {
      "Host": "api.acmeinc.com",
      "Accept": "*/*",
      "Connection": "Keep-Alive",
      "Content-Type": "application/json",
      "Content-Length": "126",
      "Accept-Encoding": "gzip"
    },
    "body": {
      "items": [
        {
          "direction_type": 1,
          "item_id": "fwdsfrf",
          "liked": false
        },
        {
          "direction_type": 2,
          "item_id": "d43d3f",
          "liked": true
        }
      ]
    }
  },
  "response": {
    "time": "2019-08-08T04:45:42.924",
    "status": 500,
    "headers": {
      "Vary": "Accept-Encoding",
      "Pragma": "no-cache",
      "Expires": "-1",
      "Content-Type": "application/json; charset=utf-8",
      "Cache-Control": "no-cache"
    },
    "body": {
      "Error": "InvalidArgumentException",
      "Message": "Missing field location"
    }
  },
  "user_id": "my_user_id",
  "company_id": "my_company_id",
  "session_token":"end_user_session_token",
  "tags": "tag1, tag2"
}

For more information about the different fields of Moesif's event model, see the following table or the Moesif Node.js API documentation.

Name	Required	Description
request	Yes	The object that specifies the API request.
request.time	Yes	Timestamp for the request in ISO 8601 format.
request.uri	Yes	Full URI such as https://api.com/?query=string including host, query string, and so on.
request.verb	Yes	The HTTP method—for example, GET and POST.
request.api_version	No	API Version you want to tag this request with such as 1.0.0.
request.ip_address	No	IP address of the client. If not set, Moesif uses the IP address of your logging API calls.
request.headers	Yes	Headers of the request as a Map<string, string> object. Multiple headers with the same key name should be combined together such that the values are joined by a comma. For more information, see HTTP Header Protocol on w3.org
request.body	No	Body of the request in JSON format or base64 encoded binary data. To specify the transfer encoding, use request.transfer_encoding.
request.transfer_encoding	No	A string that specifies the transfer encoding of the request body sent to Moesif. If not specified, Moesif assumes the request body assumed to be JSON or text. Only supported value is base64 for sending binary data like protocol buffers.
response	No	The object that specifies the response message. If not set, it implies a null response such as a timeout.
response.time	Yes	Timestamp for the response in ISO 8601 format.
response.status	Yes	HTTP response status code number such as 200 OK or 500 Internal Server Error.
response.ip_address	No	IP address of the responding server.
response.headers	Yes	Headers of the response as a Map<string, string> object. Multiple headers with the same key name should be combined together such that the values are joined by a comma. For more information, see HTTP Header Protocol on w3.org
response.body	No	Body of the response in JSON format or base64 encoded binary data. To specify the transfer encoding, use response.transfer_encoding
response.transfer_encoding	No	A string that specifies the transfer encoding of the request body sent to Moesif. If not specified, Moesif assumes the body to be JSON or text. Only supported value is base64 for sending binary data like protocol buffers.
session_token	Recommended	The end user session token such as a JWT or API key, which may or may not be temporary. Moesif automatically detects the session token if not set.
user_id	Recommended	Identifies this API call to a permanent user ID.
metadata	No	A JSON Object consisting of any custom metadata to be stored with this event.

debug

Data type	Default
Boolean	undefined

Set to true to print debug logs if you're having integration issues.

Capture Outgoing API Calls

If you want to capture all outgoing API calls from your Node.js app to third parties like Stripe or to your own dependencies, call startCaptureOutgoing() to start capturing.

const moesif = require('moesif-aws-lambda');
var moesifMiddleware = moesif(options);
moesifMiddleware.startCaptureOutgoing();

The same set of options also applies to outgoing API calls, with a few key differences:

There are several configuration option functions that take request and response object as arguments. The request and response objects passed into those functions are not Express or Node.js request or response objects when the request is outgoing, but Moesif mocks some of the fields for convenience.

Only a subset of the Node.js request or response fields are available, specifically the following:

mo_mocked

Data type	Description
Boolean	Set to true if it is a mocked request or response object, for example, outgoing API call.

headers

Data type	Description
Object	A mapping of header names to header values. Case sensitive.

url

Data type	Description
String	The full request URL.

method

Data type	Description
String	The HTTP method such as GET or POST.

statusCode

Data type	Description
Number	The HTTP response status code number.

getHeader

Data type	Parameters	Return type	Description
Function	(String)	String	Reads out a header on the request. Name is case insensitive

get

Data type	Parameters	Return type	Description
Function	(String)	String	Reads out a header on the request. Name is case insensitive

body

Data type	Description
JSON object	The request body as sent to Moesif.

Examples

See the example AWS Lambda function that uses this middleware.

The following examples demonstrate how to add and update customer information.

Update a Single User

To create or update a user profile in Moesif, use the updateUser() function.

var moesifMiddleware = moesif(options);

// Only userId is required.
// Campaign object is optional, but useful if you want to track ROI of acquisition channels
// See https://www.moesif.com/docs/api#users for campaign schema
// metadata can be any custom object
var user = {
  userId: '12345',
  companyId: '67890', // If set, associate user with a company object
  campaign: {
    utmSource: 'google',
    utmMedium: 'cpc',
    utmCampaign: 'adwords',
    utmTerm: 'api+tooling',
    utmContent: 'landing'
  },
  metadata: {
    email: 'john@acmeinc.com',
    firstName: 'John',
    lastName: 'Doe',
    title: 'Software Engineer',
    salesInfo: {
        stage: 'Customer',
        lifetimeValue: 24000,
        accountOwner: 'mary@contoso.com'
    }
  }
};

moesifMiddleware.updateUser(user, callback);

The metadata field can contain any customer demographic or other info you want to store. Moesif only requires the userId field.

This method is a convenient helper that calls the Moesif API library. For more information, see the function documentation in Moesif Node.js API reference.

Update Users in Batch

To update a list of users in one batch, use the updateUsersBatch() function.

var moesifMiddleware = moesif(options);

// Only userId is required.
// Campaign object is optional, but useful if you want to track ROI of acquisition channels
// See https://www.moesif.com/docs/api#users for campaign schema
//
// Define the users. 
var user = {
  userId: '12345',
  companyId: '67890', // If set, associate user with a company object
  campaign: {
    utmSource: 'google',
    utmMedium: 'cpc',
    utmCampaign: 'adwords',
    utmTerm: 'api+tooling',
    utmContent: 'landing'
  },
  // Metadata can be any custom object
  metadata: {
    email: 'john@acmeinc.com',
    firstName: 'John',
    lastName: 'Doe',
    title: 'Software Engineer',
    salesInfo: {
        stage: 'Customer',
        lifetimeValue: 24000,
        accountOwner: 'mary@contoso.com'
    }
  }
};

// Put the users you inside an array.
var users = [user]

// Call the function with the list of users.
moesifMiddleware.updateUsersBatch(users, callback);

The metadata field can contain any customer demographic or other info you want to store. MOesif only requires the userId field.

This method is a convenient helper that calls the Moesif API library. For more information, see the function documentation in Moesif Node.js API reference.

Update a Single Company

To update a single company, use the updateCompany() function.

var moesifMiddleware = moesif(options);

// Only companyId is required.
// Campaign object is optional, but useful if you want to track ROI of acquisition channels
// See https://www.moesif.com/docs/api#update-a-company for campaign schema
// metadata can be any custom object
var company = {
  companyId: '67890',
  companyDomain: 'acmeinc.com', // If domain is set, Moesif will enrich your profiles with publicly available info
  campaign: {
    utmSource: 'google',
    utmMedium: 'cpc',
    utmCampaign: 'adwords',
    utmTerm: 'api+tooling',
    utmContent: 'landing'
  },
  metadata: {
    orgName: 'Acme, Inc',
    planName: 'Free Plan',
    dealStage: 'Lead',
    mrr: 24000,
    demographics: {
      alexaRanking: 500000,
      employeeCount: 47
    }
  }
};

moesifMiddleware.updateCompany(company, callback);

The metadata field can contain any company demographic or other information you want to store. Moesif only requires the companyId field.

This method is a convenient helper that calls the Moesif API library. For more information, see the function documentation in Moesif Node.js API reference.

Update Companies in Batch

To update a list of companies in one batch, use the updateCompaniesBatch() function.

var moesifMiddleware = moesif(options);

// Only companyId is required.
// Campaign object is optional, but useful if you want to track ROI of acquisition channels
// See https://www.moesif.com/docs/api#update-a-company for campaign schema
//
// Define your companies.
var company = {
  companyId: '67890',
  companyDomain: 'acmeinc.com', // If domain is set, Moesif will enrich your profiles with publicly available info
  campaign: {
    utmSource: 'google',
    utmMedium: 'cpc',
    utmCampaign: 'adwords',
    utmTerm: 'api+tooling',
    utmContent: 'landing'
  },
  // Metadata can be any custom object
  metadata: {
    orgName: 'Acme, Inc',
    planName: 'Free Plan',
    dealStage: 'Lead',
    mrr: 24000,
    demographics: {
      alexaRanking: 500000,
      employeeCount: 47
    }
  }
};

// Put the companies inside an array.
var companies = [company]

// Call the function with the list of companies.
moesifMiddleware.updateCompaniesBatch(companies, callback);

The metadata field can contain any company demographic or other information you want to store. Moesif only requires the companyId field.

This method is a convenient helper that calls the Moesif API library. For more information, see the function documentation in Moesif Node.js API reference.

Additional Documentation

For more information and examples, see the following:

• REST API Example: an AWS Lambda REST API built with Express.js.
• Apollo GraphQL Example: an AWS Lambda GraphQL API built with Apollo.
• Moesif, Middy, and Serverless Example: an example showcasing how to use this middleware with Middy and Serverless Framework.

How to Get Help

If you face any issues using this middleware, try the troubheshooting guidelines. For further assistance, reach out to our support team.

Explore Other Integrations

Explore other integration options from Moesif:

• Server integration options documentation
• Client integration options documentation