CloudFormation is Amazon Web Service's tool for creating and managing "stacks" of other AWS resources as code. Cumulus is a tool we wrote at catchoftheday.com.au to help you manage your stacks in CloudFormation and build bigger logical stacks from multiple cloudformation stacks. https://github.com/cotdsa/cumulus.

1. AWS Infrastructure
as code
CloudFormation and Cumulus

2. Who we are
 Ash Caire
WebOps Lead at Catch Group
 Peter Hall
WebOps Engineer at Catch Group
Twitter: @peterkh

3. Catch Group
 catchoftheday.com.au
 scoopon.com.au
 groceryrun.com.au
 eatnow.com.au
 mumgo.com.au

4. AWS CloudFormation
“... an easy way to create and manage a collection of
related AWS resources ... ”
- http://aws.amazon.com/cloudformation/
Uses JSON templates to describe “stacks” of resources

5. Full CloudFormation Example

6. Simple CloudFormation Example

7. Simple CloudFormation Example

8. Simple CloudFormation Example

9. Simple CloudFormation Example

10. Simple CloudFormation Example

11. Simple CloudFormation Example

12. So basically…
 Create almost any AWS resources with one API call
 Once created, stacks can be updated or deleted
 Templates are re-usable and can be used to create
multiple stacks simultaneously. Resources are assigned
dynamic names
 Resources are tagged throughout the stack, with stackname, stack-id and logical-id (name of template
resource)

13. CloudFormation Demo

14. It works great! …except
 Templates are JSON files. No comments. Not the easiest
format for humans to write
 Templates are standalone and complete. No inclusion of
other templates
 Creation of stacks requires manual specification of
template parameters

15. …which leads to
Very large template files with a “data centre” worth of
resources in it
or
Smaller templates with lots of manual parameters to feed
each one
or…

16. Stack resources in templates
 It is possible to create a CloudFormation stack inside a
stack
 Once created, cannot update the parameters of an
inside stack by updating the outside stack template
(update of outside stack will fail)
 Template for inside stack needs to be uploaded to an S3
bucket before stack creation
We wanted a better way!

17. Cumulus
 Python command line tool to add extra awesome to
CloudFormation
 Concept of a mega stack, made up of multiple
CloudFormation stacks.
 Adds an extra mega-stack yaml file on top of
Cloudformation JSON templates
 Written by CatchOfTheDay WebOps team

18. What does this give us?
 Keep CloudFormation template files small and re-usable
 Single file for a mega stack, including all its parameters
 Stacks can be dependent on each other and have
dynamic parameter values from other stack
resources
 More time writing YAML, less time writing JSON
 Watch stack events in near real-time

19. Cumulus YAML file example
 See:
https://github.com/cotdsa/cumulus/blob/master/exam
ples/cumulus_example_stack.yaml

20. Cumulus Demo

22. Future improvements
 Handle larger templates by using S3 upload
 Find a way to show meaningful diffs between running
stacks and local templates before doing an update
 Abstract away JSON templates altogether?
 Generally more robust code, better error handling and
writing tests

23. Please use and improve
Open to pull requests, issues and ideas
or even just let us know you are getting value from it...
https://github.com/cotdsa/cumulus

24. Questions?