import json, sys, cdsapi

with open('/input/request.json') as req:
    request = json.load(req)

cds = cdsapi.Client(
        request.get('url'), 
        request.get('uuid') + ':' + request.get('key')
        )

cds.retrieve(
        request.get('variable'), 
        request.get('options'), 
        '/output/' +request.get('filename')
        )