Re: [Fab-user] external role definitions

[Morgan Goose]

Sounds cool, you have it up anywhere (gihub/bitbucket/googlecode/etc)?

goose

On Thu, Nov 18, 2010 at 10:04:26PM +0000, Michael Gliwinski wrote:
> Hello fab(ulous) people!
> 
> I've been using Fabric for a while now but am new to the list.  I'm just 
> catching up with archives and I've noticed that the question of loading roles 
> from external sources sometimes pops up.
> 
> I have this class which I use in my fabfiles that I thought could be useful 
> to 
> some, and if it would, I can submit a patch to put it in contrib or even 
> directly in fabric.state.
> 
> Basically, the class inherits from the builtin dict and behaves like a normal 
> dictionary with additional option to load data from external source.  A list 
> of sources can be passed to load_from method and the first available (i.e. 
> first one which returns without raising exception) will be used.
> 
> A source can be a local path to file, a URL or a callable which should return 
> a mapping of roles to host lists.
> 
> In my implementation data from file or URL is expected to be in YAML format, 
> but since this would mean additional dependency I can change it to something 
> else.
> 
> In any case the source_loader attribute can also be reassigned to a custom 
> function that loads other formats.
> 
> For example, given a file 'roles.yml' with contents: 'foo: [bar, baz]\n':
> 
>   >>> r = RoleDefs()
>   >>> r.load_from(['nonexistent.yml', 'roles.yml'])
>   >>> r['foo']
>   ['bar', 'baz']
> 
> The source is loaded "lazily" - only when the first missing key is accessed 
> which means an instance of RoleDefs can be assigned to env.roledefs without 
> causing delay on every fab invocation.
> 
> My usecase for this is that I usually export the roles (or access them 
> directly) from Spacewalk/Cobbler, but sometimes e.g. when I'm working over 
> VPN 
> I have to connect through SSH tunnels (port redirs) through a gateway, so I 
> have a local file with some roles redefined in terms of those redirections.
> 
> Anyways, if you're interested I can do something about getting that into 
> Fabric.  Let me know sure.
> 
> Thanks for the great work!
> 
> Michael
> 
> 
> -- 
> Michael Gliwinski
> Henderson Group Information Services
> 9-11 Hightown Avenue, Newtownabby, BT36 4RT
> Phone: 028 9034 3319
> 
> -- 
> Michael Gliwinski
> Henderson Group Information Services
> 9-11 Hightown Avenue, Newtownabby, BT36 4RT
> Phone: 028 9034 3319
> 
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