PyScripts rating module

PyScripts rating module

The PyScripts module allows you to create your own rating module. A script is supposed to process the given data and to set the different prices.

CAUTION: If you add several PyScripts, the order in which they will be executed is not guaranteed.

Custom module example

Price definitions

import decimal

# Price for each flavor. These are equivalent to hashmap field mappings.
flavors = {
    'm1.micro': decimal.Decimal(0.65),
    'm1.nano': decimal.Decimal(0.35),
    'm1.large': decimal.Decimal(2.67)

# Price per MB / GB for images and volumes. These are equivalent to
# hashmap service mappings.
image_mb_price = decimal.Decimal(0.002)
volume_gb_price = decimal.Decimal(0.35)

Price calculation functions

# These functions return the price of a service usage on a collect period.
# The price is always equivalent to the price per unit multiplied by
# the quantity.
def get_compute_price(item):
    if not item['desc']['flavor'] in flavors:
        return 0
        return (decimal.Decimal(item['vol']['qty'])
               * flavors[item['desc']['flavor']])

def get_image_price(item):
    if not item['vol']['qty']:
        return 0
        return decimal.Decimal(item['vol']['qty']) * image_mb_price

def get_volume_price(item):
    if not item['vol']['qty']:
        return 0
        return decimal.Decimal(item['vol']['qty']) * volume_gb_price

# Mapping each service to its price calculation function
services = {
    'compute': get_compute_price,
    'volume': get_volume_price,
    'image': get_image_price

Processing the data

def process(data):
    # The 'data' parameter is a list of dictionaries containing a
    # "usage" and a "period" field
    for d in data:
        usage = d['usage']
        for service_name, service_data in usage.items():
            # Do not calculate the price if the service has no
            # price calculation function
            if service_name in services.keys():
                # A service can have several items. For example,
                # each running instance is an item of the compute service
                for item in service_data:
                    item['rating'] = {'price': services[service_name](item)}
    return data

# 'data' is passed as a global variable. The script is supposed to set the
# 'rating' element of each item in each service
data = process(data)

Using your Script for rating

Enabling the PyScripts module

To use you script for rating, you will need to enable the pyscripts module

$ cloudkitty module-enable -n pyscripts
| Module    | Enabled |
| pyscripts | True    |

Adding the script to CloudKitty

Create the script and specify its name.

$ cloudkitty pyscripts-script-create -n my_awesome_script -f
| Property  | Value                                        |
| checksum  | 7650349ba3a913cef526dfb953575042ec3332e1     |
| data      | from __future__ import print_function        |
|           | from cloudkitty import rating                |
|           |                                              |
|           | import decimal                               |
|           |                                              |
|           |       {...}                                  |
|           |                                              |
|           | data = process(data)                         |
|           |                                              |
| name      | my_awesome_script                            |
| script_id | 93de054f-9d6f-40b0-8e4f-9b8fee8cad04         |
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