POC/WIP: Swift metadata header middleware

Middleware for Swift to add a header value which can be used by other middleware to tag entries, for example proxy_logging or Ceilometer.

Installation

1. Install metadataheaders middleware:

   sudo python setup.py install

2. Add a filter entry for metadataheaders to your proxy-server.conf and configure which metadata entries should be included as a header value:

   [filter:metadataheaders] use = egg:metadataheaders#metadataheaders header_container_metadata = log-to, header_object_metadata = sensible-object-log

3. Alter your proxy-server.conf pipeline and add the metadataheaders middleware:

   [pipeline:main] pipeline = catch_errors healthcheck cache tempauth metadataheaders proxy-logging proxy-server

4. Restart your proxy server:

   swift-init proxy reload