Lemme Check That

A crude html resource change checker that's a pleasure to deploy.

Looks for changes in an html resource at a given url. Checks if the number of elements matching a given css selector in the html has changed. If there's been a change, sends email to that effect to a set of recipients.

All the inputs are given via environment variables. They are:

• BEANSTALK_URL: The url to connect to beanstalkd with. The schema should be beanstalk, so something like beanstalk://localhost:33333/.
• CHECK_URL: The url to check for changes in. Must point to an html resource.
• CHECK_SELECTOR: The css selector to look for changes in.
• NOTIFY_RECIPIENTS: A json formatted list of recipients for notification when there's a change. Something like ["[email protected]", "[email protected]"]
• SMTP_HOST: The host to connect to for sending email notification
• SMTP_PORT: The port for that same purpose.
• FROM_ADDRESS: The address the notification emails should say they're from.

All of these inputs are required.

Implementation Details

Uses Clockwork to schedule periodic checks. Beanstalk is used as a message queue. A python worker listens for Clockwork's messages and performs the checks.

This's meant to be deployed in a Heroku Cedar like environment, but isn't actually deployable to Heroku as far as I know, because of the mix of Python and Ruby. For now, I just use foreman locally and in a tiny prod deployment.