I was vexed by this error when setting up a host with Puppet 3.6.2 on FreeBSD 9.2 recently:

Error: Could not set 'present' on ensure: uninitialized class variable @@lock in Object at 52:/usr/local/etc/puppet/modules/ldap/manifests/init.pp
Error: Could not set 'present' on ensure: uninitialized class variable @@lock in Object at 52:/usr/local/etc/puppet/modules/ldap/manifests/init.pp
Wrapped exception:
uninitialized class variable @@lock in Object
Error: /Stage[main]/Ldap/Package[net/nss_ldap]/ensure: change from absent to present failed: Could not set 'present' on ensure: uninitialized class variable @@lock in Object at 52:/usr/local/etc/puppet/modules/ldap/manifests/init.pp

The line it referred to was trying to install the net/nss_ldap package. I had run pkg2ng on the host and included the pkgng module in the node’s manifest.

When I searched for @@lock in the Puppet source code, the only references I found were from the freebsd package provider. That provider uses the deprecated pkg_ commands and for some reason is included in Puppet while pkgng is not.

[longb4-local@testdb /usr/ports/sysutils/puppet]$ sudo make fetch extract patch configure
[longb4-local@testdb /usr/ports/sysutils/puppet]$ cd work/puppet-3.6.2/
[longb4-local@testdb /usr/ports/sysutils/puppet/work/puppet-3.6.2]$ find . -exec grep -HnsiI '@@lock' {} \;                                                                                                                                                                       
./lib/puppet/provider/package/freebsd.rb:18:  class_variable_set(:@@lock, Mutex.new)
./lib/puppet/provider/package/freebsd.rb:73:    @@lock.synchronize do

Solution

Since Puppet was trying to use the non-working pkg_ commands, I made it use the pkgng package provider when installing packages on the affected node by adding this to the node manifest:

Package {
    provider => pkgng,
}

After that, Puppet runs completed successfully.