Contents

---
title: "Stack Policies"
category: "dsl"
weight: 8
anchors:
  - title: "Template Usage"
    url: "#template-usage"
  - title: "Library Usage"
    url: "#library-usage"
---

## Stack Policies

AWS CloudFormation includes support for stack policies. These
policies add an extra layer of control that restricts or allows
actions to be taken on specific resources within a stack.
SparkleFormation includes support for extracting inline stack
policy information from SparkleFormation templates which can
then be applied to stacks.

* [AWS CFN Stack Policies](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/protect-stack-resources.html)

### Template Usage

Resource policies can be defined within a SparkleFormation
template. This allows for policies to be programatically generated
in the same manner as the stack template itself.

~~~ruby
template = SparkleFormation.new(:test) do
  resources.my_resource do
    policy do
      allow 'Modify'
      deny 'Replace'
    end
  end
end
~~~

### Library Usage

SparkleFormation can extract stack policies from a template after
it has been compiled. Once extracted, the policy can be applied
to the stack as dictated by the API.

~~~ruby
template = SparkleFormation.new(:test) do
  resources.my_resource do
    policy do
      allow 'Modify'
      deny 'Replace'
    end
  end
end

policy = template.generate_policy
~~~

This generates a policy data structure:

~~~ruby
{
  "Statement" => [
    {
      "Effect" => "Allow",
      "Action" => [
        "Update:*"
      ],
      "Resource" => "*",
      "Principal" => "*"
    },
    {
      "Effect" => "Allow",
      "Action" => [
        "Update:Modify"
      ],
      "Resource" => "LogicalResourceId/MyResource",
      "Principal" => "*"
    },
    {
      "Effect" => "Deny",
      "Action" => [
        "Update:Replace"
      ],
      "Resource" => "LogicalResourceId/MyResource",
      "Principal" => "*"
    }
  ]
}
~~~

Version data entries

5 entries across 5 versions & 1 rubygems

Version	Path
sparkle_formation-1.1.8	docs/stack-policies.md
sparkle_formation-1.1.6	docs/stack-policies.md
sparkle_formation-1.1.4	docs/stack-policies.md
sparkle_formation-1.1.2	docs/stack-policies.md
sparkle_formation-1.1.0	docs/stack-policies.md