introduce configobj as configuration backend

config.py

@@ -0,0 +1,48 @@
+"""
+Interface to access:
+ - local configuration
+ - shared configuration
+ - shared runtime state
+
+All configuration is stored in a single ini-file and
+persistent state is pickle-dumped into a binary file.
+
+TODO: check lock safety
+TODO: manage persistent state in configobj
+"""
+import json
+import logging
+import sys
+from configobj import ConfigObj
+from validate import Validator
+
+__initialized = False
+__config_store = ConfigObj('local_config.ini', configspec='local_config.ini.spec')
+
+validator = Validator()
+result = __config_store.validate(validator)
+
+if not result:
+    print('Config file validation failed!')
+    sys.exit(1)
+else:
+    __initialized = True
+    __config_store.write()
+
+
+def get(key):
+    if not __initialized:
+        raise RuntimeError("not __initialized")
+    try:
+        return __config_store[key]
+    except KeyError as e:
+        logger = logging.getLogger(__name__)
+        logger.warn('conf(): unknown key ' + str(key))
+        print(json.dumps(__config_store, indent=2))
+        raise
+
+
+def set(key, val):
+    __config_store[key] = val
+    __config_store.write()
+    return None