cloudformations 4.1 spec

• Description
• Tracking
• Analysis
• Use Cases
  • Create Stack
  • Delete Stack
  • Update Stack
  • Cancel Update Stack
  • Describe/List Stack
  • Describe/List Stack Resource(s)
  • Describe Stack Events
  • Validate Template
    • TODO: Do we need to enumerate handling all different resource types?
• Elements
  • Cloud Formation Service
  • Template Parser
  • Function Evaluator
  • Stack Entity Manager
  • Stack Resource Entity Manager
  • Stack Event Entity Manager
  • Dependency Manager
  • Resource Manager
  • Workflow Manager
• Workflows & Coordination
• Interactions
• Abstractions
• Behaviours
• References
• Notes

Description

As a cloud user, I would like to use AWS Cloudformation templates in the system, so I don't have to repeatedly create multi-layered applications by hand.

As a cloud user, I would like support for additional Cloudformation resource types than were done in 4.0, including S3 Resources, and whatever resources are necessary to enable AWS::CloudFormation::CloudInit (AWS::Cloudformation::WaitCondition)

As a cloud user, I would like to be able to delete a stack that is being created.

Tracking

PRD-93 JIRA (eucalyptus.atlassian.net)

PRD-94 JIRA (eucalyptus.atlassian.net)

ARCH-69 JIRA (eucalyptus.atlassian.net)

Analysis

TODO

Use Cases

Create Stack

A user initiates a Create Stack request based on a template and other input parameters.

Delete Stack

A user initiates a Delete Stack request.

Update Stack

A user initiates an Update Stack request based on a template and other input parameters.

Cancel Update Stack

A user initiates an Cancel Update Stack request

Describe/List Stack

A user initiates a describe request for Stack information. (API calls are DescribeStack or ListStack)

Describe/List Stack Resource(s)

A user initiates a describe request for Resource information about a given stack.. (API calls are DescribeStackResource, DescribeStackResources or ListStackResources)

Describe Stack Events

A user initiates a describe request for events related to a given stack.

Validate Template

A user initiates a request to validate a template.

TODO: Do we need to enumerate handling all different resource types?

Elements

Cloud Formation Service

A REST/Query API implementation of the AWS Cloud Formation API. Responsible for user initiated Stack CRUD operations. (Create/Update/DeleteStack and List/Describe)(Stack)* operations, as well as validate template).

Template Parser

Parses JSON templates, converts them into appropriate object representation.

Function Evaluator

Determines whether a given JSON object represents a Cloud Formation "function", validates argument types where possible, and evaluates the function, given resource, parameter, and system data as inputs.

Stack Entity Manager

Manages CRUD operations for Stack Entity objects, which represent the state of stacks as a whole.

Stack Resource Entity Manager

Manages CRUD operations for Stack Resource Entity objects, which represent the state of resources within a stack.

Stack Event Entity Manager

Manages CRUD operations for Stack Event Entity objects, which represent the events that have occurred during the lifetime of a stack. (Stack and Stack Resource state values)

Dependency Manager

Given a series of resource dependencies, perform a topological sort to determine the correct creation order of events. May need to reverse the order during delete or rollback.

Resource Manager

Manages CRUD operations for an actual Resource (such as Instance, Volume, etc). Each Resource Type will need to implement several classes for the Resource Manager to act on.

Workflow Manager

Manages current running workflows which perform Stack CRUD operations. Each workflow in SWF should have an id which can be used for cancellation, for example.

TODO: Missing: Resource breakdown into Properties (ResourceProperties) Actions (SWF Activities for create/delete/update, etc) (ResourceActions), and everything else (function "outputs" if you will (ResourceAttributes) and things like whether or not it supports Snapshots, possibly update info)

TODO: Also missing details of template parsing, and serialization of objects)

Workflows & Coordination

Interactions

EC2 User -> Cloud Formation Service : Cloud Formation API actions

Cloud Formation Service -> Template Parser: Parses template before stack modification operations occur.

Cloud Formation Service -> Workflow Manager: Kicks off workflows for stack creation, deletion, update, or cancellation.

Template Parser -> Function Evaluator: Evaluates functions as part of template evaluation

Template Parser -> Dependency Manager : Determines resource order once dependency order is determined.

Resource Manager-> Function Evaluator : Once other resources are created, resource properties are recomputed with function references to other resources.

Function Evaluator-> Stack Resource Entity Manager : Function evaluation may require resource properties to evaluate the 'Ref' function.

Stack Entity Manager -> Entities : perform CRUD operations

Stack Resource Entity Manager -> Entities : perform CRUD operations

Stack Event Entity Manager -> Entities : perform CRUD operations

Workflow Manager -> Stack Entity Manager : Update stack state during Stack CRUD operations.

Workflow Manager -> Stack Event Entity Manager : Create new events during stack or resource state change.

Resource Manager -> Stack Resource Entity Manager: Update resource state during Resource CRUD operations

Resource Manager -> External MSGS service or AWS SDK client to send CRUD commands for Resources.

Workflow Manager -> Resource Manager: Create resources one at a time during Stack Create, delete during delete, etc.

Abstractions

Behaviours

References

Notes

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tag:confluence tag:rls-4.1 tag:cloudformations