This Apache NiFi tempalate show how to execute a python script with the NiFi flow. More importantly, it shows how to capture the input and output flowFile metadata. This has been tested within NiFi 1.0.0.
Here's the NiFi flow:
1.) Read data.json file
2.) Use the ExecuteScript processor to parse json and perform arbitrary python processing.
3.) Write attributes to json
4.) From here, the results can be saved to a simple .json file, to HDFS, sent to Kafka, Solr, etc.