Hi all,
a recurring problem with the namevars are resources that do not have a
natural unique single-property key. For example, mysql users are defined
by their username and the host(-pattern) they are connection from.
Traditionally, this was solved by ugly hackery in the type. In the
windows session at the puppetcamp, Markus and I developed the idea of
associating a set of patterns/syntaxes with the namevar to automatically
parse such multi-key titles and automatically put them into proper
parameters, which can then be validated, munged and used without needing
to know about the actual syntax elsewhere in the type/provider.
I'll start with an example, of how this could look like:
Puppet::Type.newtype(:mysql_user) do
@doc = "Manage a mysql database user."
ensurable
newtitle do
pattern "([...@]+)@([...@]+)", :user, :host
pattern "([...@]+)", :user
end
newparam(:user) do
desc "The username."
end
newparam(:host) do
desc "The host, the users connects from. This may be a pattern
using '%' and '_'."
defaultto "%"
end
Patterns would be tried in order and match groups assigned to the
specified parameters. Having no pattern match woul
This could be used in the following ways:
mysql_user {
"foo": ;
"f...@%": ; # both 'f...@%'
"bar": host => "localhost";
"b...@localhost": ; # both 'b...@localhost'
}
Mysql_user { host => "webserver" }
mysql_user { [ "frob", "frub" ]: }
# expands to 'f...@webserver' and 'f...@webserver'
mysql_user {
"frob": host => "web1";
"frob": host => "web2";
"frob": host => "web3";
}
The last stanza shows how this can be used to confusing effects. This
could be mitigated by allowing using arrays in parameters. For example
creating four users:
mysql_user {
[ "frob", "frub" ]:
host => [ "web1", "web2" ]
}
Here are some illegal constructs:
# Setting a property twice
mysql_user {
"foo": user => "bar";
"f...@%": host => "localhost";
}
# redefine resources
mysql_user {
"frob": ;
"f...@%": ;
"foo": host => "localhost";
"f...@localhost": ;
}
# pattern match fails:
mysql_user {
[ "", "@", "foo@", "@localhost", "f...@bar@localhost" ]: ;
}
For more flexibility when parsing, the list-of-paramnames could be
replaced by blocks:
pattern "complicated_regexp" do
# insert disgusting hack here
end
The block would have to return true or false to accept or reject the title.
By substituting the param names into the patterns, puppet could
automatically create documentation like this:
Patterns:
1) u...@host:
user must be [...@]+
host must be [...@]+
2) user:
user must be [...@]+
user: The username.
host: The host, the users connects from. This may be a pattern using
'%' and '_'.
This could be enhanced by specifying additional docstrings with the
patterns.
Of course, this is currently vapour-ware, as it'll need some changes in
the puppet core to handle the new uniqueness, but I hope to accelerate
the development by providing a good spec/discussion of how the
"user-facing" side should look like.
Looking forward to your feedback,
Best Regards, David
--
dasz.at OG Tel: +43 (0)664 2602670 Web: http://dasz.at
Klosterneuburg UID: ATU64260999
FB-Nr.: FN 309285 g FB-Gericht: LG Korneuburg
--
You received this message because you are subscribed to the Google Groups "Puppet
Developers" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/puppet-dev?hl=en.
