Fix Kubernetes config provider for recent changes in Kub API

Kubernetes secret volumes are now mounted as read-only, so we have to write the files *only* via the Kub API

Fixes https://jira.coreos.com/browse/QUAY-911

util/config/provider/basefileprovider.py

@@ -0,0 +1,70 @@
+import os
+import logging
+
+from util.config.provider.baseprovider import (BaseProvider, import_yaml, export_yaml,
+                                               CannotWriteConfigException)
+
+logger = logging.getLogger(__name__)
+
+class BaseFileProvider(BaseProvider):
+  """ Base implementation of the config provider that reads the data from the file system. """
+  def __init__(self, config_volume, yaml_filename, py_filename):
+    self.config_volume = config_volume
+    self.yaml_filename = yaml_filename
+    self.py_filename = py_filename
+
+    self.yaml_path = os.path.join(config_volume, yaml_filename)
+    self.py_path = os.path.join(config_volume, py_filename)
+
+  def update_app_config(self, app_config):
+    if os.path.exists(self.py_path):
+      logger.debug('Applying config file: %s', self.py_path)
+      app_config.from_pyfile(self.py_path)
+
+    if os.path.exists(self.yaml_path):
+      logger.debug('Applying config file: %s', self.yaml_path)
+      import_yaml(app_config, self.yaml_path)
+
+  def get_config(self):
+    if not self.config_exists():
+      return None
+
+    config_obj = {}
+    import_yaml(config_obj, self.yaml_path)
+    return config_obj
+
+  def config_exists(self):
+    return self.volume_file_exists(self.yaml_filename)
+
+  def volume_exists(self):
+    return os.path.exists(self.config_volume)
+
+  def volume_file_exists(self, filename):
+    return os.path.exists(os.path.join(self.config_volume, filename))
+
+  def get_volume_file(self, filename, mode='r'):
+    return open(os.path.join(self.config_volume, filename), mode=mode)
+
+  def get_volume_path(self, directory, filename):
+    return os.path.join(directory, filename)
+
+  def list_volume_directory(self, path):
+    dirpath = os.path.join(self.config_volume, path)
+    if not os.path.exists(dirpath):
+      return None
+
+    if not os.path.isdir(dirpath):
+      return None
+
+    return os.listdir(dirpath)
+
+  def requires_restart(self, app_config):
+    file_config = self.get_config()
+    if not file_config:
+      return False
+
+    for key in file_config:
+      if app_config.get(key) != file_config[key]:
+        return True
+
+    return False