Make sure the parent dir of a file path exists before writing the file

Fixes when the `extra_ca_certs` directory doesn't exist when using the new custom certs tool

util/config/provider/fileprovider.py

@@ -6,6 +6,16 @@ from util.config.provider.baseprovider import (BaseProvider, import_yaml, export
 
 logger = logging.getLogger(__name__)
 
+def _ensure_parent_dir(filepath):
+  """ Ensures that the parent directory of the given file path exists. """
+  try:
+    parentpath = os.path.abspath(os.path.join(filepath, os.pardir))
+    if not os.path.isdir(parentpath):
+      os.makedirs(parentpath)
+  except IOError as ioe:
+    raise CannotWriteConfigException(str(ioe))
+
+
 class FileConfigProvider(BaseProvider):
   """ Implementation of the config provider that reads the data from the file system. """
   def __init__(self, config_volume, yaml_filename, py_filename):
@@ -54,8 +64,13 @@ class FileConfigProvider(BaseProvider):
 
   def write_volume_file(self, filename, contents):
     filepath = os.path.join(self.config_volume, filename)
-    with open(filepath, mode='w') as f:
-      f.write(contents)
+    _ensure_parent_dir(filepath)
+
+    try:
+      with open(filepath, mode='w') as f:
+        f.write(contents)
+    except IOError as ioe:
+      raise CannotWriteConfigException(str(ioe))
 
     return filepath
 
@@ -75,6 +90,9 @@ class FileConfigProvider(BaseProvider):
 
   def save_volume_file(self, filename, flask_file):
     filepath = os.path.join(self.config_volume, filename)
+    _ensure_parent_dir(filepath)
+
+    # Write the file.
     try:
       flask_file.save(filepath)
     except IOError as ioe: