Service hooks for third-party integration in Errorception
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Errorception Service Hooks

What is this?

Errorception is a service that collects and reports JavaScript errors as they occur in your users' browsers. You might want real-time notifications about such errors as they happen. There could be several ways in which you might prefer to receive these notifications, maybe even using third-party tools and services. This repo houses a collection of such notification integrations – the service hooks.

Want your favorite service on Errorception? Create an issue, or even better, send a pull request. Contributions highly encouraged.

How does it work?

  1. All client-side JS errors that occur are dumped into a queue to be picked up by the service hooks application running on Errorception's servers.
  2. If a project on Errorception has service hooks set up, the configuration settings of those services are passed on to this library, along with the error, so that the service call can be made.
  3. The actual implementation of making the service call – the very guts of the service hook application – is handled by this library.

Anatomy of a service hook

The hooks are ridiculously easy to implement. A typical hook implementation is just one function (onError) with very few lines of code (usually just making an HTTP call). For example, the following code is a complete WebHooks implementation:

exports.onError = function(error, settings, done) {
		url: settings.url,
		method: "post",
		body: JSON.stringify(error)
	}, done);

Check it out – the actual WebHook code in production use at Errorception isn't too different from this.

The error argument

The error argument contains information about the error, quite unsurprisingly. A typical error object looks as follows:

    isInline: true,
    message: "\"_WidgetManager\" is undefined",
    userAgent: "Mozilla/5.0 (Linux; U; Android 4.1.2; en-us; GT-I9100G Build/JZO54K) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30",
    when: "after",
    scriptPath: null,
    page: "",
    date: "2012-11-12T15:31:02.576Z",
    isFirstOccurrence: true,
    webUrl: "",
    apiUrl: ""

Depending on the service, different fields might be interesting. Probably the most interesting of the lot is the webUrl key in the object, since it's a link to the error's details page in Errorception.

The settings argument

The settings argument contains configuration settings for the service. These settings are configured at the time of enabling the service in Errorception's settings.

The settings object's specific keys and values depends on the service that's being implemented. For example, in the WebHook implementation, a service.url key is available for use. The service.url is populated by Errorception's settings UI. You would typically use settings for things like API keys or security tokens – stuff that's different for each project and that you don't want to share publicly.

Currently, the settings UI (and consecutively the keys in the settings object) is managed manually. That is, if you want to integrate a service hook, you'll have to send me a pull request, and I'll make the necessary UI to ensure that the settings object has the keys you want. Details below.

The settings object's values are pre-validated so that the hook code can be minimal. The hooks neither need to validate the presence of keys nor the preferred format of their values.

The done argument

done is just a function that should be called when the job of making the service hook call is complete. This is the standard node.js style of notifying the caller that the function's task is complete.

Steps to contribute a service hook

Service hook contributions will be accepted for:

  • Production web applications
  • Popular Internet protocols (IRC, Email, Jabber, etc.)
  • Self-hosted open-source projects (Jira, Bugzilla, etc.)

If you want a hook for a home-grown internal application that no one else might be interested in, you probably just want to use a WebHook.

Prerequisites: You will need to have git installed on your computer (get it here), and will need a GitHub account. You will also need a recent version of node.js (get it here).

  1. Fork this repo.
  2. Create a directory with an approprate name, in hooks/, for your hook code.
  3. Create an index.js file in this hooks/service-name directory. Use the following template to get started:
    var request = require("request");
    exports.serviceName = "MyServiceName";	// Replace this with an appropriate value = {
    	// Fill in as many fields as you can
    	name: "Your name",
    	email: "",
    	github: "yourGithubHandle",
    	twitter: "yourTwitterHandle"
    exports.onError = function(error, settings, done) {
    	// Your code for the hook implementation goes here
    Your personal details are required so that credit can be given where it's due, and so that there's a way to contact you in case the need arises.
  4. Install dependencies by running npm install in the root of your clone directory.
  5. Avoid installing additional dependencies. The request module is already available as a dependency, so all your HTTP needs are covered. You usually won't need more than this. If you must install a dependency, make sure it's lightweight, minimal, reliable, well tested, and from a trusted source. If you are unsure, get in touch and I'll help you. Install your dependency by using npm install --save <dependancy-name>.
  6. Create a file in hooks/service-name with detailed documentation about your service hook. This file is used to render documentation in Errorception's UI when a user is enabling the service hook, so should consist of documentation of the fields that are needed to make the hook work.
  7. Send a pull request to this repo.

Once your pull request has been accepted and merged in, I'll manually make the UI for collecting the data you'd want in your copy of the settings object. Once that's done, your hook will be live on Errorception. This process will only take a day or two.

Testing your service hook

You can use the simulate-hook.js script from the command-line to simulate a service hook call. The usage is as follows:

$ node simulate-hook.js <service-name> '{"json": "settings"}'
  • service-name is the name of the directory you've created in hooks/.
  • The last argument should be a valid JSON. This object will be passed into onError as the settings object.
  • The error object is picked up automatically from error-payload.json.

For example, when I was developing the webhook service hook, I was using the following command.

$ node simulate-hook.js webhook '{"url": "http://localhost:5555/hook"}'

Combine that with nc -l 5555 on a different shell, and I could see the WebHook's HTTP POST coming to my settings.url. Easy peasy!