Moesif Node.js Middleware Documentation

by Moesif, the API analytics and API monetization platform.

Moesif Node.js middleware automatically logs incoming and outgoing API calls and sends 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.

Notes

• Previously, this NPM package was called moesif-express. In version 3.0, it has been renamed to moesif-nodejs to reflect support for any Node.js app.
• The library can capture both incoming and outgoing API Calls depending on how you configure the SDK. For more information, see the examples.
• To make sure the SDK captures request body, if you use a body parser middleware like body-parser, apply Moesif middleware after it.

Who This Middleware is For

The middleware works with REST APIs, GraphQL APIs (such as with Apollo), and more.

This SDK supports any Node.js framework including Express, Koa, and Nest.js. See the examples for more information.

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-nodejs

Configure the Middleware

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

How to Use

The following step shows how to import Moesif for an example app using Express.js.

1. Import the Module

// 1. Import Modules
var express = require('express');
var app = express();
var moesif = require('moesif-nodejs');

// 2. Set the options, the only required field is applicationId.
var options = {

  applicationId: 'YOUR_MOESIF_APPLICATION_ID',

  logBody: true,

  identifyUser: function (req, res) {
    if (req.user) {
      return req.user.id;
    }
    return undefined;
  },

  getSessionToken: function (req, res) {
    return req.headers['Authorization'];
  }
};

// 3. Initialize the middleware object with options
var moesifMiddleware = moesif(options);


// 4a. Start capturing outgoing API Calls to 3rd parties like Stripe
// Skip this step if you don't want to capture outgoing API calls
moesifMiddleware.startCaptureOutgoing();

// 4b. Use the Moesif middleware to start capturing incoming API Calls
// If you have a body parser middleware, apply Moesif middleware after any body parsers.
// Skip this step if you don't want to capture incoming API calls
app.use(moesifMiddleware);

Replace YOUR_MOESIF_APPLICATION_ID with your Moesif Application ID.

If you are using babel or newer versions of Node.js, you can using more modern syntax for importing—for example, import moesif from 'moesif-nodejs'; . If you are using ECMAScript modules (ES modules), you can try the following method:

const moesifImported = await import('moesif-nodejs');
const moesif = moesifImported.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.

var moesif = require('moesif-nodejs');
const http = require('http');

var options = {
  applicationId: 'YOUR_MOESIF_APPLICATION_ID',
  logBody: true,
};

var server = http.createServer(function (req, res) {
  moesif(options)(req, res, function () {
    // Callback
  });

  req.on('end', function () {

    res.write(JSON.stringify({
      message: "hello world!",
      id: 2
    }));
    res.end();
  });
});

server.listen(8080);

Replace YOUR_MOESIF_APPLICATION_ID with your Moesif Application ID.

3. Call your API

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

Troubleshoot

For a general troubleshooting guide that can help you solve common problems, see Server Troubleshooting Guide. For troubleshooting issues with capturing outgoing API calls, see Troubleshoot Capturing Outgoing API Calls

Other troubleshooting supports:

• FAQ
• Moesif support email

Troubleshoot Capturing Outgoing API Calls

For instrumenting or capturing outgoing API calls, it instruments standard HTTP or HTTPs from Node.js core. However, some third party SDKS may use customized HTTP clients to make API calls, which may interfere with instrumentation.

Here are some tips:

• Some SDKS, like the Stripe Node.js SDK, even though they have a very customized http client, lets you swap out to a more standard HTTP client like node-fetch.

  import fetch from 'node-fetch'; // you may have to add by `npm install node-fetch` or yarn equivalent.
  import Stripe from 'stripe';
  
  const stripeClient = Stripe('your secret key', {
    // basically you are using node fetch as the httpClient.
    httpClient: Stripe.createFetchHttpClient(fetch),
  });

• Turn outgoingPatch flag to true in configuration options to make an attempt to cover non-standard HTTP client usage. However, it may not cover all cases.

  {
  const moesifOptions = {
    // ... other options,
    outgoingPatch: true
  };

Repository Structure

.
├── app.js
├── dist/
├── eslint.config.mjs
├── images/
├── lib/
├── LICENSE
├── package.json
├── package-lock.json
├── README.md
├── test/
└── tsconfig.json

Configuration Options

Note: If you're using Koa, you can access the state object through request.state.

The following sections describe the available configuration options for this middleware. You can set these options in the Moesif initialization options object. See the example Express.js application 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	(req, res)	String

A function that takes Express.js Request and Response 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.

var options = {
  identifyUser: function (req, res) {
    // your code here must return the user id as a string. Example Below
    return req.user ? req.user.id : undefined;
  }
}

identifyCompany

Data type	Parameters	Return type
Function	(req, res)	String

A function that takes Express.js Request and Response 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.

var options = {
  identifyCompany: function (req, res) {
    // your code here must return the company id as a string. Example Below
    return req.headers['X-Organization-Id']
  }
}

getSessionToken

Data type	Parameters	Return type
Function	(req, res)	String

A function that takes Express.js Request and Response objects as arguments and returns a session token such as an API key.

var options = {
  getSessionToken: function (req, res) {
    // your code here must return a string. Example Below
    return req.headers['Authorization'];
  }
}

getApiVersion

Data type	Parameters	Return type
Function	(req, res)	String

A function that takes Express.js Request and Response objects as arguments and returns a string to tag requests with a specific version of your API.

var options = {
  getApiVersion: function (req, res) {
    // your code here must return a string. Example Below
    return req.headers['X-Api-Version']
  }
}

getMetadata

Data type	Parameters	Return type
Function	(req, res)	Object

A function that takes Express.js Request and Response 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.

var options = {
  getMetadata: function (req, res) {
    // your code here:
    return {
      foo: 'custom data',
      bar: 'another custom data'
    };
  }
}

skip

Data type	Parameters	Return type
Function	(req, res)	Boolean

A function that takes Express.js Request and Response 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 /:

var options = {
  skip: function (req, res) {
    // your code here must return a boolean. Example Below
    if (req.path === '/' || req.path === '/health') {
      // Skip logging traffic to root path or health probe.
      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 Express request or response 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.

import _ from 'lodash';

var options = {
  maskContent: function(event) {
    // remove any field that you don't want to be sent to Moesif.
    const newEvent = _.omit(event, ['request.headers.Authorization', 'event.response.body.sensitive_field'])
    return newEvent;
  }
};

Moesif's event model format looks like this:

{
  "request": {
    "time": "2022-08-08T04:45:42.914",
    "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": "2022-08-08T04:45:42.924",
    "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.

noAutoHideSensitive

Data type	Default
Boolean	false

Before sending any data for analysis, automatically checks the data (headers and body) and one way hash strings or numbers that look like a credit card numbers or passwords. Set to true if you want to implement your specific maskContent function or you want to send all data to be analyzed.

callback

Data type	Parameters	Return type
Function	(error)	null

For for internal errors. For example, if there has been an error sending events to Moesif or network issue, you can use this to check for any issues with integration.

disableBatching

Data type	Default
Boolean	false

By default, Moesif Express batches the events. Set to true if you want to send the API events one by one.

batchSize

Data type	Default
Number	200

If batching is enabled, this defines the batch size of API events that triggers flushing of queue and sending the data to Moesif. The value of the batch size must be greater than one.

batchMaxTime

Data type	Default
Number	2000

If batching is enabled, this defines the maximum wait time (approximately) in milliseconds before triggering flushing of the queue and sending to Moesif. The value must be greater than 500 milliseconds.

retry

Data type	Default
Number	1

The number of times to retry the middleware fails to send data to Moesif. The value must be a number between 0 and 3.

requestMaxBodySize

Data type	Default
Number	100000

The maximum request body size in bytes to log when sending the data to Moesif.

responseMaxBodySize

Data type	Default
Number	100000

The maximum response body size in bytes to log when sending the data to Moesif.

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.

var moesifMiddleware = moesif(options);
moesifMiddleware.startCaptureOutgoing();

You can use this method to capture outgoing API calls even if you are not using the Express middleware or having any incoming API calls.

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

There are several configuration option functions that take request and response objects 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.

Koa Support

Several of the Moesif configuration options take a Node.js request ane response objects as arguments. You can access the Koa state object through req.state.

As an example, many Koa auth middleware save the authenticated user on ctx.state.user. You can access it through Moesif options like identifyUser:

  identifyUser: function (req, res) {
    if (req.state && req.state.user) {
      return req.state.user.sub;
    }
    return undefined;
  },

Examples

• View example app with Express.js.
• View example app with Koa.
• View example app with Apollo.js GraphQL.
• View example app with Express GraphQL.
• View example app with Next.js
• View example app with Fastify

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
  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
// metadata can be any custom object
var user = {
  userId: '12345',
  companyId: '67890', // If set, associate user with a company object
  metadata: {
    email: 'john@acmeinc.com',
    firstName: 'John',
    lastName: 'Doe',
    title: 'Software Engineer',
    salesInfo: {
        stage: 'Customer',
        lifetimeValue: 24000,
        accountOwner: 'mary@contoso.com'
    }
  }
};

var users = [user]

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
  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
// 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
  metadata: {
    orgName: 'Acme, Inc',
    planName: 'Free Plan',
    dealStage: 'Lead',
    mrr: 24000,
    demographics: {
      alexaRanking: 500000,
      employeeCount: 47
    }
  }
};

var companies = [company]

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.

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