Add support for adding request contextual data to configuration objects.

mig/shared/conf.py

@@ -32,6 +32,7 @@
 import os
 import sys
 
+from mig.shared.configuration import RuntimeConfiguration
 from mig.shared.defaults import MIG_ENV
 from mig.shared.fileio import unpickle
 
@@ -42,7 +43,6 @@ def get_configuration_object(config_file=None, skip_log=False,
     and disable_auth_log arguments are passed on to allow skipping the default
     log initialization and disabling auth log for unit tests.
     """
-    from mig.shared.configuration import Configuration
     if config_file:
         _config_file = config_file
     elif os.environ.get('MIG_CONF', None):
@@ -63,7 +63,7 @@ def get_configuration_object(config_file=None, skip_log=False,
         skip_log = True
         disable_auth_log = True
 
-    configuration = Configuration(_config_file, False, skip_log,
+    configuration = RuntimeConfiguration(_config_file, False, skip_log,
                                   disable_auth_log)
     return configuration
 

mig/shared/configuration.py

@@ -1,3 +1,3 @@
 #!/usr/bin/python
 # -*- coding: utf-8 -*-
 #
@@ -2851,6 +2851,47 @@
         return peers_dict
 
 
+class RuntimeConfiguration(Configuration):
+    """A more specific version of the Configuration which additionally supports
+    the notion of a context.
+
+    Contextual information that is relevant to the duration of a request is
+    required in certain cases e.g. to support templating. Given Configuration
+    objects are threaded into and throough almost all the necessary codepaths
+    to make this information available, they are an attractive place to put
+    this - but a Configuration is currently loaded from static per-site data.
+
+    Resolv this ambiguity with this subclass - a raw Confioguration will
+    continute to represent the static data while a specialised but entirely
+    compatible object is handed to request processing codepaths.
+    """
+
+    def __init__(self, config_file, verbose=False, skip_log=False,
+                 disable_auth_log=False):
+        super().__init__(config_file, verbose, skip_log, disable_auth_log)
+        self._context = None
+
+    def context(self, namespace=None):
+        """Retrieve the context or a previously registered namespace.
+        """
+
+        if self._context is None:
+            self._context = {}
+        if namespace is None:
+            return self._context
+        # allow the KeyError to escape if the registered namespace is missing
+        return self._context[namespace]
+
+    def context_set(self, value, namespace=None):
+        """Attach a value as named namespace within the active congifuration.
+        """
+        assert namespace is not None
+
+        context = self.context()
+        context[namespace] = value
+        return value
+
+
 if '__main__' == __name__:
     conf = Configuration(os.path.expanduser('~/mig/server/MiGserver.conf'),
                          True)

tests/test_mig_shared_configuration.py

@@ -1,3 +1,3 @@
 # -*- coding: utf-8 -*-
 #
 # --- BEGIN_HEADER ---
@@ -42,7 +42,7 @@
 
 def _to_dict(obj):
     return {k: v for k, v in inspect.getmembers(obj)
-            if not (k.startswith('__') or _is_method(v))}
+            if not (k.startswith('_') or _is_method(v))}
 
 
 class MigSharedConfiguration(MigTestCase):