Caching/Headers question

[Rob Miller]

On 23 Nov 2011, at 18:17, Jo Galara wrote:

> On 11/21/2011 07:11 PM, Hugo Cisneiros (Eitch) wrote:
> 
>> Other way is to cache like forever and let the back-end notify varnish
>> to ban the object from the cache. It's a very efficient method for not
>> having varnish download the file from back-end unnecessarily :)
> 
> How can I do that?



When faced with the same issue, I wrote a Ruby script that includes functionality for purging and refreshing an entire domain:

https://github.com/robmiller/Varnish-Toolkit

It supports things like purging a page along with all its external assets, purging a whole domain, and purging and then spidering a whole domain. 

We often use it when we make a change to, say, the header or footer of a website that has a very slow backend (as some of our Magento ecommerce sites do); that way, our spider gets all of the slow requests and our end users get none.

Using this, we don't generally worry about TTLs; we cache everything for a really long time, then purge when we know we need to (either automatically, when a new piece of content goes live, or manually when we make a change to a stylesheet or template file).

You probably shouldn't use it unless you write lurker-friendly bans,[1] though.

Rob

[1]: http://kristianlyng.wordpress.com/2010/07/28/smart-bans-with-varnish/

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