Question

Is it possible to force Heroku to clear out the Varnish cache from within an application (i.e. without pushing a new repository)?

Answer 1

Though this Heroku mailing list message is a year old, I haven’t found anything to contradict it.

No, there’s no official way to
manually expire your cache on Varnish.
If you need more control over your
cache (ie setting when it expires is
not enough) I’d recommend using
Memcache instead.

I doubt this has changed. Since Varnish is run outside the context of the Rails app, there probably isn’t a Varnish class or anything like that, so no method that would purge the cache. Looks like you’re on your own.