Make jinja complain if variable is undefined

Author: DoubleMalt

metacompose/cli/main.py

@@ -1,7 +1,7 @@
 import sys
 import os
 import yaml
-from jinja2 import Environment, FileSystemLoader
+from jinja2 import Environment, FileSystemLoader, StrictUndefined
 
 def env_override(value, key):
   return os.getenv(key, value)
@@ -11,7 +11,8 @@ def main():
     template_file_name = "meta-compose.yml"
     data_file_name = "meta-compose-data.yml"
 
-    jinja = Environment(loader=FileSystemLoader("."))
+    jinja = Environment(loader=FileSystemLoader("."), undefined=StrictUndefined)
+
     jinja.filters['env'] = env_override
 
     template = jinja.get_template(template_file_name)