do_export.py

#!/bin/env python
import json
import requests
import sys
from requests.auth import HTTPBasicAuth
from pprint import pprint

def fetch_metadata(fl):
  with open(fl, "r") as content:
    data = json.load(content)
    return data

def do_export(cvv_id, from_history_id = None):
  url = "http://localhost:3000/katello/api/content_exports/export" 
  post_json = {'destination_server':"downstream.example.com", 'content_view_version_id': cvv_id}
  if from_history_id:
    post_json['from_history_id'] = from_history_id
  return requests.post(url, auth=HTTPBasicAuth('admin', 'changeme'), json = post_json)

if len(sys.argv) == 1:
  print("usage: ", sys.argv[0], '<Content View Version Id> <from_history_id>')
  sys.exit(-1)
pprint(do_export(*sys.argv[1:]).json())