builtin functions: added virt_check function and support expansion in include

The virt_check builtin function expands to the first argument if
running inside virtual machine, otherwise it expands to the second
argument (when on bare metal or in case of error). It uses virt-what
as a backend.

So now the following can be used to lower fragmentation of Tuned profiles:

[main]
include=virtual-${f:virt_check:guest:host}

So it will include virtual-guest if running inside virtual machine,
otherwise it includes virtual-host.

Resolves: rhbz#1426654

Signed-off-by: Jaroslav Škarvada <jskarvad@redhat.com>

tuned/profiles/functions/function_virt_check.py

@@ -0,0 +1,22 @@
+import os
+import tuned.logs
+import base
+from tuned.utils.commands import commands
+
+class virt_check(base.Function):
+	"""
+	Checks whether running inside virtual machine (VM) or on bare metal.
+	If running inside VM expands to argument 1, otherwise expands to
+	argument 2 (even on error).
+	"""
+	def __init__(self):
+		# 2 arguments
+		super(self.__class__, self).__init__("virt_check", 2)
+
+	def execute(self, args):
+		if not super(self.__class__, self).execute(args):
+			return None
+		(ret, out) = self._cmd.execute(["virt-what"])
+		if ret == 0 and len(out) > 0:
+			return args[0]
+		return args[1]

tuned/profiles/loader.py

@@ -72,7 +72,7 @@ class Loader(object):
 			config = self._load_config_data(filename)
 			profile = self._profile_factory.create(name, config)
 			if "include" in profile.options:
-				include_name = profile.options.pop("include")
+				include_name = self._variables.expand(profile.options.pop("include"))
 				self._load_profile([include_name], profiles, processed_files)
 
 			profiles.append(profile)