On Thu, Nov 11, 2010 at 12:50:02PM -0800, Eric Snow wrote:
> How do you dynamically create classes?
You don't. 2.6 has parameterized classes but that's not quite what you
mean.
>
> For instance, I have a bunch of users to make. I have all their
> usernames. Each is the same as the others except for the username and
> one other value. I don't want to have to spell out a User for each,
> but would rather set up them up dynamically, in a much cleaner way
> (and more maintainable).
You can use resource defaults to take out most of the drudgery
User {
managed => true,
shell = '/bin/bash'
}
Then you only need type out the varying properties of each user.
>
> It looks like parameterized classes would mostly do it, but is the
> syntax for including a parameterized class the same everywhere? Can a
> parameterized class be virtual?
No. Resources can be virtual but not classes.
If you were hoping to be able to create all of these users by iterating
through a hash, or something similar, then Puppet really doesn't support
that. Puppet's DSL is declaritive and can't be treated like some OO
language (I wish Luke had chosen a name other than "class" for Puppet's
classes; it only confuses people).
Have you noticed that Puppet has arrays and hashes but doesn't have a
keys() function? You *could* have a hash of users and their properties
$users = { john => { shell => '/bin/bash', uid => '501' }, david => {
shell => '/bin/tcsh', uid = '501' }
and have a define which consulted that hash, as in
define hash_user ( $user_hash ) {
user { $name:
ensure => 'present',
managed => true,
shell => $users[$name][shell],
uid => $user_hash[$name][uid]
}
}
But since there is no keys function, you can't do
hash_user { [ keys($users) ]: user_hash => $users }
You have to do
hash_user { [ 'john', 'david' ]: user_hash => $users }
which isn't really saving you a lot.
Bluntly, Puppet wants you to declare your resources explicitly.
> As well, I was hoping to set up some defines in the dynamically
> created user so that they could be used from the class's namespace.
> The alternative is to do them separately and pass in the same
> information that I already passed in to the class, which seems messier
> than just providing them from the class's namespace.
I think there may be a misplaced word in there; it doesn't seem to make
entire sense.
--
Bruce
Get thee behind me, Stan: for it is written, thou hast gotten me into
another fine mess. -- Oliver 4:8
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