[Puppet Users] YAML as File resource template Error , "can't convert Hash to String"

Using exported resources I'm trying to have a host export a File resource
generated from a yaml template, to another host. The host that gets the
exported resource is throwing errors like this

err: Failed to apply catalog: Parameter content failed: Munging failed for
value {"parameters"=>{"macaddress_p2p1"=>"00:15:17:80:5A:3E",
"macaddress_p2p2"=>"00:15:17:80:5A:3F",
"macaddress_eth0"=>"00:1E:C9:55:12:C7",
"macaddress_eth1"=>"00:1E:C9:55:12:C9", "operatingsystem"=>"CentOS",
"serialnumber"=>"", "interfaces"=>"eth0,eth1,lo,p2p1,p2p2",
"fqdn"=>"<snip>", "ipaddress_p2p1"=>"", "ipaddress_p2p2"=>"", "uuid"=>"",
"ipaddress_eth0"=>"", "ipaddress_eth1"=>"<snip>", "productname"=>"",
"operatingsystemrelease"=>"6.3"}, "name"=>"<snip>"} in class content: can't
convert Hash into String

Here is the parts of the module...

class racktables::export (
$site,
$yamls_dir = 'UNSET'
) inherits racktables::params {

$yamls_dir_REAL = $yamls_dir ? {
'UNSET' => "${conf_dir}/${site}/yamls",
default => $yamls_dir,
}

@@file { "racktables_host_${::hostname}.yaml":
content => template('racktables/host.yaml.erb'),
path => "${yamls_dir_REAL}/${::hostname}.yaml",
tag => "host_yaml_for_${site}",
}

}

define racktables::instance (
...
) {
<snip>

File <<| tag == "host_yaml_for_${name}" |>> {
require => File[$yaml_exports_REAL],
}

<snip>
}

Template...

# cat templates/host.yaml.erb
---
name: "<%= scope.lookupvar('::hostname') %>"
parameters:
interfaces: "<%= scope.lookupvar('::interfaces') %>"
fqdn: "<%= scope.lookupvar('::fqdn') %>"
operatingsystemrelease: "<%= scope.lookupvar('::operatingsystemrelease')
%>"
operatingsystem: "<%= scope.lookupvar('::operatingsystem') %>"
productname: ""
uuid: ""
serialnumber: ""
<% scope.lookupvar('::interfaces').split(',').each do |interface| -%>
<% unless interface.eql? "lo" -%>
ipaddress_<%= interface %>: "<%=
scope.lookupvar("::ipaddress_#{interface}") %>"
macaddress_<%= interface %>: "<%=
scope.lookupvar("::macaddress_#{interface}") %>"
<% end -%>
<% end -%>


Is there some catch to using a YAML file for the template content? Would
it be better to use Ruby DSL for the racktables::export class and generate
a hash -> sort -> to_yaml and have that be set as the content?

Thanks
- Trey