Improvement of k8s Deployments update

* Deployment will be updated only if service-related configuration
  was changed
* SilentUndefined handler to ignore undefined variables of jinja
  templates was added

Change-Id: Iad384ee447268cba44cbfacba81118ec44ca31c3

fuel_ccp/common/jinja_utils.py

@@ -3,13 +3,31 @@ import os
 import jinja2
 
 
+class SilentUndefined(jinja2.Undefined):
+    def _fail_with_undefined_error(self, *args, **kwargs):
+        return ''
+
+    __add__ = __radd__ = __mul__ = __rmul__ = __div__ = __rdiv__ = \
+        __truediv__ = __rtruediv__ = __floordiv__ = __rfloordiv__ = \
+        __mod__ = __rmod__ = __pos__ = __neg__ = __call__ = \
+        __getitem__ = __lt__ = __le__ = __gt__ = __ge__ = __int__ = \
+        __float__ = __complex__ = __pow__ = __rpow__ = \
+        _fail_with_undefined_error
+
+
 def str_to_bool(text):
     return text is not None and text.lower() in ['true', 'yes']
 
 
-def jinja_render(path, context, functions=()):
+def jinja_render(path, context, functions=(), ignore_undefined=False):
+    kwargs = {}
+    if ignore_undefined:
+        kwargs['undefined'] = SilentUndefined
+    else:
+        kwargs['undefined'] = jinja2.StrictUndefined
+
     env = jinja2.Environment(loader=jinja2.FileSystemLoader(
-        os.path.dirname(path)), undefined=jinja2.StrictUndefined)
+        os.path.dirname(path)), **kwargs)
     env.filters['bool'] = str_to_bool
     for func in functions:
         env.globals[func.__name__] = func