Error when trying to ensure non-existent services are stopped

When managing the `ensure` state for a service, the provider queries the
service status to determine if it's running or not. However, if the
service doesn't exist, then it returns that the service is `stopped`.

When trying to ensure a non-existent service is stopped, puppet thinks
the service is "insync", so returns exit code 0.

This commit updates the systemd provider's enable method to return
either :running, :stopped or :absent. To differentiate between `stopped`
vs `absent`, the provider first checks if the service exists.

This adds `absent` as a valid value for the `ensure` property, however,
it can't be set on a provider, since we don't want to remove services:

    puppet resource service ufw ensure=absent
    Error: The systemd provider can not handle attribute ensure

lib/puppet/application/resource.rb

@@ -234,8 +234,10 @@ def find_or_save_resources(type, name, params)
           resource = Puppet::Resource.new( type, name, :parameters => params )
 
           # save returns [resource that was saved, transaction log from applying the resource]
-          save_result = Puppet::Resource.indirection.save(resource, key)
-          [ save_result.first ]
+          save_result, report = Puppet::Resource.indirection.save(resource, key)
+          status = report.resource_statuses[resource.ref]
+          raise "Failed to manage resource #{resource.ref}" if status&.failed?
+          [ save_result ]
         end
       else
         if type == "file"

lib/puppet/provider/service/systemd.rb

@@ -159,6 +159,20 @@ def daemon_reload?
     end
   end
 
+  # override base#status
+  def status
+    if exist?
+      status = service_command(:status, false)
+      if status.exitstatus == 0
+        return :running
+      else
+        return :stopped
+      end
+    else
+      return :absent
+    end
+  end
+
   def enable
     self.unmask
     systemctl_change_enable(:enable)

lib/puppet/type/service.rb

@@ -110,6 +110,8 @@ def insync?(current)
         provider.start
       end
 
+      newvalue(:absent)
+
       aliasvalue(:false, :stopped)
       aliasvalue(:true, :running)