Moesif AWS Lambda Middleware

Middleware (NodeJS) to automatically log incoming API requests/responses from AWS Lambda functions and send to Moesif for error analysis. Designed for APIs that are hosted on AWS Lambda and using Amazon API Gateway as a trigger.

This middleware expects the Lambda proxy integration type. If you're using AWS Lambda with API Gateway, you are most likely using the proxy integration type.

Source Code on GitHub

Package on NPMJS

How to install

npm install --save moesif-aws-lambda

How to use

The following shows how import the controllers and use:

1. Import the module:

// 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
    }
};
 
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);
 
 

2. Enter Moesif Application Id.

You can find your Application Id from Moesif Dashboard -> Top Right Menu -> App Setup

Repo file structure

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

Configuration options

identifyUser

Type: (event, context) => String identifyUser is a function that takes AWS lambda event and context objects as arguments and returns a userId. This helps us attribute requests to unique users. Even though Moesif can automatically retrieve the userId without this, this is highly recommended to ensure accurate attribution.

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

getSessionToken

Type: (event, context) => String getSessionToken a function that takes AWS lambda event and context objects as arguments and returns a session token (i.e. such as an API key).

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

getTags

Type: (event, context) => String getTags is a function that takes AWS lambda event and context objects as arguments and returns a comma-separated string containing a list of tags. See Moesif documentation for full list of tags.

options.getTags = function (event, context) {
  // your code here. must return a comma-separated string.
  if (event.path.startsWith('/users') && event.httpMethod == 'GET'){
    return 'user'
  }
  return 'random_tag_1, random_tag2'
}

getApiVersion

Type: (event, context) => String getApiVersion is 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'
}

skip

Type: (event, context) => Boolean skip is a function that takes AWS lambda event and context objects as arguments and returns true if the event should be skipped (i.e. not logged)
The default is shown below and 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

Type: MoesifEventModel => MoesifEventModel maskContent is a function that takes the final Moesif event model (rather than the AWS lambda event/context objects) as an argument before being sent 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;
}

EventModel format:

{
  "request": {
    "time": "2016-09-09T04:45:42.914",
    "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": "2016-09-09T04:45:42.914",
    "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": "mndug437f43",
  "session_token":"end_user_session_token",
  "tags": "tag1, tag2"
}
 

For more documentation regarding what fields and meaning, see below or the Moesif Node API Documentation.

updateUser method

A method is attached to the moesif middleware object to update the users profile or metadata.

'use strict'
const moesif = require('moesif-aws-lambda');
 
const moesifOptions = {
    applicationId: 'Your Moesif application_id',
 
};
var moesifMiddleware = moesif(options);
var user = {
  userId: 'your user id',  // required.
  metadata: {
    email: 'user@email.com',
    name: 'George'
  }
}
 
moesifMiddleware.updateUser(user, callback);
 

The metadata field can be any custom data you want to set on the user. The userId field is required.

Other integrations

To view more more documentation on integration options, please visit the Integration Options Documentation.