Right now when one uses the REST POST /seed/create API, a directory is created within /var/some/path/here which is create if you are working locally with the Nutch server e.g. on one machine. It is however not suitable for using the REST API in distributed deployments where seeds needs to be present within HDFS. More documentation on this topic is available at
There are also various mailing list threads regarding use of the REST and this injector url issue described above needs to be addressed.
Sujen Shah CC for context.