I'm trying to use InvokeHTTP to write to webhdfs via Knox (into a kerberos secured cluster). Knox is using a self-signed certificate and that is not likely to change. If I use curl with the -k param to allow self-signed certs I can successfully write to HDFS. When using InvokeHTTP though, it barfs on the self-signed cert ("unable to find valid certification path to requested target"). I'm using Apachie NiFi 1.0 (though same problem with 0.7) with HDP 2.2 cluster. Any ideas?