RoR – Get your exceptions notified via Slack

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Have you ever wanted to be one step ahead, and be notified of any unwanted exception before your users have to deal with it? If so, read this article to configure your rails application in just a few steps.

First, we are going to need two gems:

• Exception Notification. It provides a set of notifiers for sending notifications when errors occur in a Rack/Rails application.
• Slack-Notifier. A simple wrapper to send notifications to Slack webhooks.

Install them as you would do with any other gem. In my case, I add them to the Gemfile and then run bundle install. Setting them up is as easy as adding a few lines in our environment files, or an initializer config file:

Rails.application.config.middleware.use ExceptionNotification::Rack,       :slack {         :webhook_url = “YOUR_WEB_HOOK_URL”       }

But wait, how do I get that YOUR_SLACK_WEB_HOOK_URL?

1. Go to https://slack.com/apps/A0F7XDUAZ-incoming-webhooks
2. Once you have logged in into your team, on the left-side panel, choose “Add Configuration.”
3. Select the Slack channel where you want to get notified, and then press “Add Incoming WebHooks integration.”
4. You are going to see a Webhook URL like https://hooks.slack.com/services/XXXXXXXX/XXXXXXXXXXXXXXXXXXXXXXXX

OK, that was easy, but how can I test that it is working?

Maybe your code is so good that it doesn’t raise an exception. In that case, we can add a rails route to test this functionality. Go to your routes.rb file and add this:

# Route for testing Exception Notification configurationget “test_exception_notifier” => “application#test_exception_notifier”

Then, in your application controller:

def test_exception_notifier    raise “Test Exception. This is a test exception to make sure the exception notifier is working.” end

Finally, visit yourhost/test_exception_notifier and voila! You should receive a slack notification looking something like this:

Slack notification example

In the message, you are going to get a full detail of the exception, including a description, the host’s name, and a full backtrace.

Let us know how this worked for you in the comments!