Extract the logic of managing SAM cloudformation stack from the the S…

[elbayaaa]

Extract the logic of managing SAM CloudFormation stack to a utility module

Which issue(s) does this change fix?

NA

Why is this change necessary?

SAM bootstrap creates/manages a S3 bucket via a CFN stack("aws-sam-cli-managed-default"). This change is to decoupl the logic of managing a SAM CFN stack from this particular "aws-sam-cli-managed-default" stack so that the logic can be reused to manage any other SAM CFN stacks.

How does it address the issue?

What side effects does this change have?

Nothing, this refactor doesn't cause any behavior change.

Checklist

• Add input/output type hints to new functions/methods
• Write design document (Do I need to write a design document?)
• Write unit tests
• Write/update functional tests
• Write/update integration tests
• make pr passes
• make update-reproducible-reqs if dependencies were changed
• Write documentation

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[elbayaaa]

this is a new logic but doesn't not result in any behavior change as the method caller(see bootstrap.py) always pass profile=None (which how it used to be)

[moelasmar]

I think we should not create a new session, the session is handled here

aws-sam-cli/samcli/cli/context.py

Lines 169 to 186 in f084cf2

	def _refresh_session(self):
	"""
	Update boto3's default session by creating a new session based on values set in the context. Some properties of
	the Boto3's session object are read-only. Therefore when Click parses new AWS session related properties (like
	region & profile), it will call this method to create a new session with latest values for these properties.
	"""
	try:
	botocore_session = botocore.session.get_session()
	boto3.setup_default_session(
	botocore_session=botocore_session, region_name=self._aws_region, profile_name=self._aws_profile
	)
	# get botocore session and setup caching for MFA based credentials
	botocore_session.get_component("credential_provider").get_provider(
	"assume-role"
	).cache = credentials.JSONFileCache()
	except botocore.exceptions.ProfileNotFound as ex:
	raise CredentialsError(str(ex)) from ex

so whenever we need to apply any changes to the AWS services session we can do it from this location only, like if we need to use specific services endpoints, so we can change in the default session, and we are sure that it will be applied to all AWS services connections

[elbayaaa]

This use case is different. The one you are referring to is for the --profile option where we execute a SAM CLI command against one AWS account. But for this use case we want to deploy a CFN template to multiple AWS accounts so we don't manage the AWS account through this --profile option.

[elbayaaa]

setting profile to None as the existing code didn't use this param anywhere

[elbayaaa]

this is a new logic but doesn't not result in any behavior change as the method caller(see bootstrap.py) always pass profile=None (which how it used to be) so this ProfileNotFoundexception will never be raised