puppet functions exec windows command line - windows

Question

Currently i am trying to automate the start mode in windows server services. i tried to use puppetlabs registry but realized that the module didn't work as i expected.
Basically i have list of windows services that i need to update on each server but on some servers, the services might not exist, but puppetlabs registry will just create the new key if it's not exist which is not the expected behaviour. By right, it should work as mentioned below:
Check whether the service is in the servers or not
If it does, then update the start mode as mentioned inside the manifest/hiera
If not exist, just do nothing and skip to the next service immediately
Based from what i knew, it seems the only way to check whether the service key exist or not is by using custom function. So i already tried to write some custom function using win32/registry, but was unsuccessful by getting some error such as Win32API not supported. Another way i can think of is using the reg command line to check whether the key exist or not. Here is the puppet code functions:
module Puppet::Parser::Functions
newfunction(:check_winservice_exist, :type => :rvalue) do |args|
service_name = args[0]
unless args.length > 0 then
raise Puppet::ParseError, ("check_winservice_exist(): wrong number of arguments (#{args.length}; must be > 0)")
end
command = "reg query HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\Services\\#{service_name} /f DisplayName"
result = system command
return result
#if result == true
# return result
#else
# return result
#end
end
end
When i run the simplified ruby scripts in command line, it works and return the expected value. But when i used above scripts as puppet custom functions, it always return empty.
This is my first time to write a puppet custom functions so i am not sure what i did wrong here. Please advise whether there are another alternative that i can use to resolve the issue or maybe advise on what i did wrong on the functions script

Answer 1

I managed to resolve this issue by using custom facter as suggested by Matt. Just sharing the custom facter scripts that i used. It might not be perfect as i am still not really proficient in using ruby.
require 'win32/registry'
Facter.add(:winservices) do
confine :kernel => "windows"
setcode do
keyname= 'SYSTEM\CurrentControlSet\Services'
access = Win32::Registry::KEY_ALL_ACCESS
arr = []
winservices_list = []
Win32::Registry::HKEY_LOCAL_MACHINE.open(keyname, access) do |reg|
service_lists = (reg.each_key { |key, wtime| arr.push key })
arr.each do |service|
service_key = "SYSTEM\\CurrentControlSet\\Services\\#{service}"
begin
Win32::Registry::HKEY_LOCAL_MACHINE.open(service_key, access) do |reg|
value = reg['Start']
winservices_list.push service
end
rescue
end
end
winservices_list
end
end
end
And it simply works just by adding simply checking whether the service name is in the array or not
if $service_name in $facts['winservices'] {
service { "${service_name}":
provider => 'windows',
enable => $start_real,
}
}