Add license checking to Quay

Based off of mjibson's changes

Fixes #499

util/config/provider/baseprovider.py

@@ -1,12 +1,18 @@
 import yaml
 import logging
 
+from util.config.provider.license import LICENSE_FILENAME, LicenseError, decode_license
+
 logger = logging.getLogger(__name__)
 
 class CannotWriteConfigException(Exception):
   """ Exception raised when the config cannot be written. """
   pass
 
+class SetupIncompleteException(Exception):
+  """ Exception raised when attempting to verify config that has not yet been setup. """
+  pass
+
 def import_yaml(config_obj, config_file):
   with open(config_file) as f:
     c = yaml.safe_load(f)
@@ -38,6 +44,8 @@ def export_yaml(config_obj, config_file):
 class BaseProvider(object):
   """ A configuration provider helps to load, save, and handle config override in the application.
   """
+  def __init__(self):
+    self.license = None
 
   @property
   def provider_id(self):
@@ -81,4 +89,26 @@ class BaseProvider(object):
     """ If true, the configuration loaded into memory for the app does not match that on disk,
         indicating that this container requires a restart.
     """
-    raise NotImplementedError
+    raise NotImplementedError
+
+  def validate_license(self, config):
+    """ Validates that the configuration matches the license file (if any). """
+    if not config.get('SETUP_COMPLETE', False):
+      raise SetupIncompleteException()
+
+    with self._get_license_file() as f:
+      license_file_contents = f.read()
+
+    self.license = decode_license(license_file_contents)
+    self.license.validate(config)
+
+  def _get_license_file(self):
+    """ Returns the contents of the license file. """
+    try:
+      return self.get_volume_file(LICENSE_FILENAME)
+    except IOError:
+      msg = 'Could not open license file. Please make sure it is in your config volume.'
+      raise LicenseError(msg)
+
+
+