free_port: updates recipe to use getValueFromPreviousRun from GenericBaseRecipe

slapos/recipe/free_port.py

@@ -25,12 +25,13 @@
 #
 ##############################################################################
 
-import ConfigParser
 import os
 import netaddr
 import socket
 
-class Recipe(object):
+from slapos.recipe.librecipe.generic import GenericBaseRecipe
+
+class Recipe(GenericBaseRecipe):
   """
   Uses the socket python standard library to get an unused port.
 
@@ -48,11 +49,7 @@ class Recipe(object):
     # If this check isn't done, a new port would be picked for every upgrade
     # of the software release
     try:
-      parser = ConfigParser.RawConfigParser()
-      if os.path.exists(buildout['buildout']['installed']):
-        with open(buildout['buildout']['installed']) as config_file:
-          parser.readfp(config_file)
-        port = parser.get(name, 'port')
+      port = self.getValueFromPreviousRun(name, 'port')
       # Port can be 0 in case of upgrade: some old service still runs on port,
       # so 0 is returned by default. Then, on next run, this recipe is processed
       # again until a correct value is returned