Sanitize inputs in apache recipe.

Avoid Nonetype-related errors.

slapos/recipe/apache_frontend/__init__.py

@@ -85,8 +85,20 @@ class Recipe(BaseSlapRecipe):
     domain_dict = {}
 
     for slave_instance in slave_instance_list:
+      # Sanitize inputs
       backend_url = slave_instance.get("url", None)
       reference = slave_instance.get("slave_reference")
+
+      if slave_instance.haskey("enable_cache"):
+        enable_cache = slave_instance.get("enable_cache", "").upper() in ('1', 'TRUE')
+      else:
+        enable_cache = False
+
+      if slave_instance.haskey("type"):
+        slave_type = slave_instance.get("type", "").lower()
+      else:
+        slave_type = None
+
       # Set scheme (http? https?)
       # Future work may allow to choose between http and https (or both?)
       scheme = 'http://'
@@ -120,7 +132,7 @@ class Recipe(BaseSlapRecipe):
       slave_dict[reference] = "%s%s/" % (scheme, domain)
 
       # Check if we want varnish+stunnel cache.
-      if slave_instance.get("enable_cache", "").upper() in ('1', 'TRUE'):
+      if enable_cache:
         # XXX-Cedric : need to refactor to clean code? (to many variables)
         rewrite_rule = self.configureVarnishSlave(
             base_varnish_port, backend_url, reference, service_dict, domain)
@@ -134,8 +146,7 @@ class Recipe(BaseSlapRecipe):
         # rule structure.
         # So we will have one RewriteMap for normal websites, and one
         # RewriteMap for Zope Virtual Host Monster websites.
-        if slave_instance.get("type") is not None and \
-            slave_instance.get("type", "").lower() in ['zope']:
+        if slave_type in ['zope']:
           rewrite_rule_zope_list.append(rewrite_rule)
           # For Zope, we have another dict containing the path e.g '/erp5/...
           rewrite_rule_path = "%s %s" % (domain, slave_instance.get('path', ''))