templates: Disable template execution by default

User will have to enable it by enabling it in /etc/network/ifupdown2.conf
template_enable=1

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>

config/ifupdown2.conf

@@ -4,6 +4,9 @@
 # This file contains default settings for ifupdown
 #
 
+# enable templates
+template_enable=0
+
 # default template engine (only mako is currently supported)
 template_engine=mako
 

ifupdown/ifupdownmain.py

@@ -577,6 +577,7 @@ class ifupdownMain(ifupdownBase):
         nifaces = networkInterfaces(self.interfacesfile,
                         self.interfacesfileiobuf,
                         self.interfacesfileformat,
+                        template_enable=self.config.get('template_enable', 0),
                         template_engine=self.config.get('template_engine'),
                 template_lookuppath=self.config.get('template_lookuppath'))
         nifaces.subscribe('iface_found', self._save_iface)

ifupdown/networkinterfaces.py

@@ -32,7 +32,8 @@ class networkInterfaces():
 
     def __init__(self, interfacesfile='/etc/network/interfaces',
                  interfacesfileiobuf=None, interfacesfileformat='native',
-                 template_engine=None, template_lookuppath=None):
+                 template_enable='0', template_engine=None,
+                 template_lookuppath=None):
         """This member function initializes the networkinterfaces parser object.
 
         Kwargs:

ifupdown/template.py

@@ -14,12 +14,15 @@ from utils import *
 class templateEngine():
     """ provides template rendering methods """
 
-    def __init__(self, template_engine, template_lookuppath=None):
+    def __init__(self, template_engine, template_enable='0',
+                 template_lookuppath=None):
         self.logger = logging.getLogger('ifupdown.' +
                     self.__class__.__name__)
         self.tclass = None
         self.tclassargs = {}
         self.render = self._render_default
+        if template_enable == '0':
+            return
         if template_engine == 'mako':
             try:
                 self.tclass = utils.importName('mako.template', 'Template')