Rich link previews can look great on Facebook. But sometimes those previews are outdated, or are missing text or images. Cachebot updates those link previews. Try it out on Facebook Messenger.
Facebook may cache a web page's open graph tags for 30 days. Sometimes it doesn't fetch the open graph tags correctly the first time, so the rich link preview looks funny.
When a user messages a URL to Cachebot, Cachebot POSTs a request to https://graph.facebook.com with two params: id (the URL) and scrape (true). This forces Facebook to re-scrape the URL's open graph tags.
Create a new Facebook app and page (if necessary). Generate a page access token; set that as the ACCESS_TOKEN environment variable. Create a random verify token and set that as the VERIFY_TOKEN environment variable.
Install the necessary gems via bundle. (You may use a .env file.)
Start a local server with rackup and open a tunnel with ngrok. In your Facebook Developer dashboard, set up webhooks. Set the callback URL to your ngrok URL and set the verify token to whatever you created earlier.
If everything's working, you can deploy this to Heroku and update the callback URL.
If you want to use Google Analytics, set the GA_TRACKING environment variable to your Google Analytics tracking ID.
Copyright 2017 Ryan Catalani
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