WP 4.6 Compat: set WP_HOME/SITEURL directly

[swalkinshaw]

WordPress/WordPress@905f4ec
changed email address handling with PHPMailer. It's not validating email
addresses. This was failing since Trellis was using string interpolation
with the HTTP_HOST constant. It wasn't being evaluated in that
context.

The solution is to set these values directly with the first canonical
site host eliminating the need for the magic constant and string
interpolation.

[runofthemill]

Continuing the conversation from #646 - Ansible provides easy access to system facts that can be used here and elsewhere: http://docs.ansible.com/ansible/playbooks_variables.html#information-discovered-from-systems-facts

I think it may be good to use {{ ansible_fqdn }} instead of a filter - I think it was in this video where Jeff talks about the idea that Ansible roles/playbooks shouldn't attempt to use Ansible as a programming language (i.e. using lots of complex logic, filters, etc.) and as a whole Trellis could probably benefit from a reduction in complexity - this (IMO) is a good place to take advantage of that!

[thisolivier]

@runofthemill Since ansible_fqdn relies on an external lookup, this could result in some very strange behaviour, see here.- I'm imagining if you're deploying the production version while the domain is still in use elsewhere. My apologies if that's not relevant here.

[fullyint]

Suppose a user setting up a new DO droplet doesn't customize the hostname to be the fqdn, leaving some default value like this:

Then hostname --fqdn and ansible_fqdn are both ubuntu-512mb-sfo1-01. Trellis could add a task to set the hostname, but I'd be inclined to stick with {{ site_hosts_canonical | first }}.

[runofthemill]

@thisolivier @fullyint I see your points - I was using it with vagrant in the context of the local dev server, which I mentioned in the other post (but not here); my only other thought is I'd just suggest leaving wp_siteurl as "${WP_HOME}/wp" to keep things DRY.