Clear Memcached on Heroku Deploy

ruby-on-rails ruby-on-rails-3 heroku memcached
Solomon picture Solomon · Oct 11, 2011 · Viewed 9.5k times · Source

What is the best way to automatically clear Memcached when I deploy my rails app to Heroku?

I'm caching the home page, and when I make changes and redeploy, the page is served from the cache, and the updates aren't incorporated.

I want to have this be totally automated. I don't want to have to clear the cache in the heroku console each time I deploy.

Thanks!

Answer

Fabrice Carrega picture Fabrice Carrega · Dec 9, 2012

I deploy my applications using a bash script that automates GitHub & Heroku push, database migration, application maintenance mode activation and cache clearing action.

In this script, the command to clear the cache is : 

heroku run --app YOUR_APP_NAME rails runner -e production Rails.cache.clear

This works with Celadon Cedar with the Heroku Toolbelt package. I know this is not a Rake-based solution however it's quite efficient.

Note : be sure you set the environment / -e option of the runner command to production as it will be executed on the development one otherwise.

Edit : I have experienced issues with this command on Heroku since a few days (Rails 3.2.21). I did not have time to check the origin the issue but removing the -e production did the trick, so if the command does not succeed, please run this one instead : 

heroku run --app YOUR_APP_NAME rails runner Rails.cache.clear

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