[development] Solving the dev->staging->live problem

[Alex Barth]

On Aug 10, 2008, at 12:22 PM, Greg Dunlap wrote:
> On Sun, Aug 10, 2008 at 6:06 AM, Victor Kane <victorkane at gmail.com>  
> wrote:
>
> Alex Barth recently contact me about exactly this, having come to  
> the exact same conclusion. He has opened an issue in deploy's issue  
> queue:
>
> http://drupal.org/node/291921
>
> He himself wrote a module quite similar to Deploy called Ports which  
> is pretty interesting and abstracts import/export a bit beyond what  
> I did. Maybe he can chime in here about what he's done because I've  
> only taken really a cursory glance at it.
>

I'm happy that this discussion is coming up.

I started writing port module for generating installer profiles and  
was then pleasantly surprised to see similarities with Greg's deploy  
module.

At port module's core there is a very simple idea: provide a hook to  
let modules define a matching export and import function. Here is the  
ports hook definition for imagecache for example:

// Implementation of hook_ports()
function imagecache_ports() {
   $ports = array();
   $ports['imagecache_presets']['name'] = t('Image cache presets');
   $ports['imagecache_presets']['export callback'] =  
'imagecache_export_presets';
   $ports['imagecache_presets']['import callback'] =  
'imagecache_import_presets';
   $ports['imagecache_presets']['type'] = PORT_STRUCTURE; // not yet  
implemented
   $ports['imagecache_presets']['version'] = '1.68.2.3';  // not yet  
implemented
   return $ports;
}

This simple approach is pretty powerful, because it makes it really  
easy to generate a single export array that contains all the  
information for importing it on a target site. In its simplest  
applications, you can copy / paste this array to your target site or  
you can use it to generate install functions for an install profile   
(both operations currently supported by port module).

After doing a first proof of concept as a result of a client project,  
I saw how similar certain approaches in deploy module are and got in  
touch with Greg. I had another look at deploy module this weekend: I'm  
actually thinking that a deploy like module and a port like module  
could play very well together by port providing the structure in which  
modules should export and import configuration and deploy providing  
the XML-RPC integration, deployment functionality and the UI.

Another module that could be implemented on top of port module is the  
install profile wizard (recent discussion on a related thread: http://drupal.org/node/230059#comment-957328) 
.

That said, port is a proof of concept, this is the current status and  
limitations:

# Basic hook_ports() system defined
# UI for copy/paste deployment of export data
# UI for generating callable PHP functions
# on-behalf implementations for menus, user roles and permissions,  
module status, content types, imagecache, nodeprofile and spaces.
# while there is a flag for PORT_STRUCTURE and PORT_CONTENT I haven't  
thought deeper about content export/import - I'm just thinking that  
it's a very closely related problem
# while there's a slot for version number, port isn't handling any  
version comparisons atm
# there is no 'update' handling, no notion of mapping
# there is no way of exporting parts of a modules configuration yet.  
While modules can define more than one export / import pair, there's  
no way of exporting just a part of one export function. e. g. export  
only certain imagecache definitions, not all of them. this one should  
be easy.

Ideas for update handling in port: I'm leaning towards not dealing  
with it on this level. In the existing implementation modules would  
deal with create new vs update by themselves. I haven't thought much  
about this though and there might be a smart helper that port could  
provide so that we know on this level what's an update and what's new.

Plans for port: don't know yet. I'm in touch with Greg on deploy and I  
plan to get in touch with Boris Mann on install profile wizards. These  
are the two projects where I see overlap.

I'd be very curious to get your thoughts on port module's approach.

Check out the code here:
http://cvs.drupal.org/viewvc.py/drupal/contributions/sandbox/alex_b/port/

-

Alex Barth
http://www.developmentseed.org/blog
tel (202) 250-3633