How do I require a resource in a Puppet definition based on an array parameter?

Question

I have a define that looks like this:

define user::sys_user($fullname, $uid, $groups, $shell='/bin/bash', $authkey, $authkey_type=rsa) {
        $username = "sys_${name}"
        group { $username:
                gid =>  $uid,
        }

        user { $username:
                require => Group[$username],
                ensure => present,
                uid => $uid,
                gid => $uid,
                groups => $groups,
                comment => $fullname,
                shell => $shell,
                managehome => true,
                allowdupe => false,
        }

        ssh_authorized_key { "${username}_authkey":
                user => $username,
                ensure => present,
                key => $authkey,
                type => $authkey_type,
        }
}

In the user resource, I am requiring the user's default group. I also want to require supplemental groups if provided by the parameter $groups.

Also, is the way I do groups => $groups going to fail if it's empty or if it's just a string (i.e., defines just one group instead of an array)?

Answer 1

Yes, groups => $groups is likely to fail. It may not fail here in particular, but this particular pattern is not safe.

Put an if statement testing whether it is set or not, and define user with and without it on the if and else bodies.