Changed the behavior of environment variables

Environment variables used to be overrides, now they are defaults. They
are only used if the resource does not supply its own value for the
given parameter.

Author: Carlos Konstanski

examples/nagios_.jinja2

@@ -3,25 +3,28 @@
 {% set object_name = resource_type[7:] %}
 {% set named_object = object_name in named_objects %}
 {% for resource in resources %}
+{% set envs_to_ignore = [] %}
 {% if resource.exported %}
 {% if "only-cross-site" not in resource.tags or localsite == "false" %}
-define {{object_name}} {
+define {{ object_name }} {
     {% if named_object %}
-    {{object_name}}_name {{resource.name}}
+    {{ object_name }}_name {{ resource.name }}
     {% endif %}
-    {% for key,value in resource.parameters.items() %}
-    {% set name_key = (object_name ~ '_' ~ key)|upper %}
+    {% for key, value in resource.parameters.items() %}
     {% if key not in metaparams or key in allowed_metaparams %}
     {% if value is iterable and value is not string %}
-    {{key}} {{value|join(", ")}}
+    {{ key }} {{ value|join(", ") }}
     {% else %}
-    {% if name_key in env %}
-    {{key}} {{env[name_key]}}
-    {% elif key|upper in env %}
-    {{key}} {{env[key|upper]}}
-    {% else %}
-    {{key}} {{value}}
+    {{ key }} {{ value }}
+    {% set _ = envs_to_ignore.append((object_name ~ '_' ~ key)|upper) %}
+    {% endif %}
     {% endif %}
+    {% endfor %}
+    {% for name in env %}
+    {% set nameparts = name.split('_') %}
+    {% if nameparts[0]|lower == object_name %}
+    {% if name not in envs_to_ignore %}
+    {{ name }} {{ env[name] }}
     {% endif %}
     {% endif %}
     {% endfor %}