Enable doctrine cache in production?

[jrjohnson]

Currently we have the cache section commented out:
https://github.com/ilios/ilios/blob/master/app/config/config_prod.yml#L9

Mainly because we were not sure what to require. We could make this configurable or we can just require a specific cache be installed (APC).

Thoughts @stopfstedt @thecoolestguy

[thecoolestguy]

So, Zend OpCache was available out the gate in PHP 5.5, but has builds available through PECL for php v5.2 - v5.4. If we're going to go force caching for everyone, I say we either bump Ilios' PHP version requirement to 5.5 or add one of those awesome dagger characters (†) to the PHP 5.4 spec requirement and mention that Zend OpCache needs to be installed if you happen to be going with 5.4... It doesn't make a lot of sense to force people to use APC when it is or is about to be deprecated.

[jrjohnson]

It looks to me like cent OS 7 has php 5.4 and I couldn't find a better version in the EPEL repos. I think the installation for us of the zend cache was a simple yum install. Was that because of our additional repositories? If it is easy to add and keep updated on a RHEL system then I'm ok with requiring php 5.4 and recommending 5.5 with the Zend cache.

[jrjohnson]

@thecoolestguy can you investigate the difficulty of installing php 5.5 on RHEL / CentOS 7? If it is a supported stack then we can go with it, otherwise I think we need to wait and stick on 5.4.

[jrjohnson]

Turns out this is a moot point as doctrine seems to only have APC support:
http://doctrine-orm.readthedocs.org/en/latest/reference/caching.html

Lets go with APC for now.