Cloudformation template in SSM Document using AWS::Include

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We are interested in storing Cloudformation templates in SSM Documents instead of S3. However, the SSM document size limit of 64kB is small and one of our templates is larger.

It would make sense to use AWS::Include and manage some parts of the large template as sub-templates, also stored as SSM Documents. According to the documentation of AWS::Include it only supports S3 URIs. It seems like an unfortunate omission given that SSM Documents have the 64kB limit.

Any plans to support ssm-doc in AWS::Include or is there some other workaround to recommend?

Thanks

asked 6 months ago399 views
1 Answer
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Hi,

You have a simpler optiony breaking your big template into a set of smaller templates (each stored as SSM document) and share the info that you need via outputs that you export into a namespace that you define. Then you read those exported values from your other templates that need those values.

Re. exports, see https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/outputs-section-structure.html

The optimal way is to organize your new templates by "layers" of resources corresponding to the dependencies between all of them.

That is what I personally use very often in similar situations.

Best,

Didier

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answered 6 months ago
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reviewed 6 months ago
  • Thanks for the suggestion!

    We already have "layered" templates using export/import as well as SSM Parameters. However, the initial template is fairly large because it is the only one that requires IAM capability during create/update (very important for the delegation of permissions).

    If we did break this template into smaller templates, we would need to perform multiple "Create Application" operations in Application Manager (or Cfn UI / CLI) for the same end result. Seems unfortunate but storing templates in SSM Documents brings important value.

    Thanks, Thomas Å.

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