A billing system for OpenStack to register products of a public cloud and periodically charge the tenants.

1. Dough:
OpenStack
Billing Project
Folsom Design Summit
2012-04-16
Luo, Zhongyue
lzyeval@gmail.com

2. TODO
Intro
Design concepts
Architecture
Example
RPCs
RDBMS model
Billing logic
Discussions
2

3. Intro
What to expect from Dough
Keep track of billing info to charge tenants
Flexible customization of payment policies
How much/often to charge for resource unit
Handles prepaid or pay-as-you-go
What Dough does not do
Keep track of tenant’s resource usage
Needs a monitoring/metering system
Deduct money from account
DIY using database as a queue
3

4. Design concepts
Highly configurable
Billing frequency, unit of measure
Asynchronous
All events are asynchronous
Independent
Pluggable clients to access other projects
Scalability
Handle billing of many users
Nova conventions
Message protocol 4

5. RPC
Architecture Database
Client
Compute
Network RDBMS Dashboard
Storage
Monitoring
Billing
(Metering)
NoSQL 5

6. RPC
Architecture Database
Client
Compute
Network RDBMS Dashboard
Storage
Collector
Monitoring
Farmer API daemon
(Metering)
Dispatch jobs Subscribe or
Collector unsubscribe
products /
Query info
Check status /
Retrieve usage /
Create purchases 6

7. Example: creating an instance
Compute
Network RDBMS Dashboard
Storage
2
Create subscription
record
Collector
{'method': 'subscribe_item',
1
'args': {
Monitoring '62a8a396d9f44ef4a655ec1d7bd3801b',
'user_id': Farmer API daemon
(Metering) '864bbc5d23ea47799ae2a702927920e9',
'tenant_id':
'region': 'deafult',
'item': 'instance',
'item_type': 'm1.tiny', Collector
'payment_type': 'hourly',
'resource_uuid': 'uuidofinstance',
'resource_name': 'nameofinstance',
}}
7

8. Example: creating an instance
Compute
Network RDBMS Dashboard
Storage
Retrieve expired
subscriptions
2
Collector
1
Request for
Monitoring charge Farmer API daemon
(Metering)
Dispatch jobs
Collector
Check status /
Retrieve usage /
Create purchases 8

9. Example: creating an instance
Compute
Network RDBMS Dashboard
Check instance
Storage status
5
3 Create purchase record /
Update subscription
Collector status and expiring
4 datetime
Retrieve instance
Monitoring usage quantity Farmer API daemon
(Metering)
Collector
9

10. Example: creating an instance
Compute
Network RDBMS 2 Dashboard
Storage
RDBMS model
1
Collector
RPCs
Monitoring
Farmer API daemon
(Metering)
Collector
3
Billing logic
10

11. RPCs
subscribe_item
Creates a subscription of a product
Subscription status: ”creating”
unsubscribe_item
Updates the status of a subscription
Subscription status: ”deleting”
query_payment_types
query_product_price
query_usage_report
11

12. RDBMS model
Created by...
Regions → region name
Items → resource name
ItemTypes → resource type name
Admin
PaymentTypes → name, interval_unit,
interval_size, is_prepaid
Products
region, item, item_type, payment_type
order_unit, order_size, price, currency
Subscriptions → product, tenant, status User
expires_at, resource_uuid
Purchases → subscription, quantity, Collector
line_total 12

13. Billing logic: Subscription states
Creation
successful Unsubscribe
creating verified
Item error
Creation error
error deleting
Deletion
error
Manually by admin
Deletion successful
terminated
13

14. Billing logic: Purchase creation
For each non-deleted expired subscription:
Status == ”creating”:
Check if item finished creation(client)
If product is prepaid:
Create purchase*
Extend expires_at**
Verify subscription
Status == ”deleting”:
Check if item finished deletion(client)
If product is not prepaid:
Create purchase*
Terminate subscription 14

15. Billing logic: Purchase creation
For each non-deleted expired subscription:
Status == ”verified”:
Check if item is valid(client)
Create purchase*
Extend expires_at**
(*)Create purchase
Insert purchase where
line_total=quantity(from monitoring )*price/unit_size
(**)Extend expires_at
+= dateutil.relativedelta(interval_unit=interval_size)
15

16. Discussions
Is this worth looking at?
Any design problems?
More requirements?
https://github.com/lzyeval/talk-OSDS-2012
16