cyclic import on ServerlessAppPlugin with 1.60.0

[alexrashed]

Description

With the release of 1.60.0, it is not possible anymore to import from samtranslator.plugins.application.serverless_app_plugin due to a cyclic import introduced with be58556.

Steps to reproduce

I used the following script to verify my tests (and to identify the commit which introduced the issue using it as a run script for git bisect):

#!/bin/bash
set -eo pipefail
rm -rf .venv
python -m venv .venv
source .venv/bin/activate
pip install -e .
python -c "from samtranslator.plugins.application.serverless_app_plugin import ServerlessAppPlugin"

Observed result

This script mentioned above fails on the v1.60.0 tag, as well as on the latest commit on develop, with the following error:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/home/localstack/Repos/serverless-application-model/samtranslator/plugins/application/serverless_app_plugin.py", line 11, in <module>
    from samtranslator.intrinsics.actions import FindInMapAction
  File "/home/localstack/Repos/serverless-application-model/samtranslator/intrinsics/actions.py", line 5, in <module>
    from samtranslator.model.exceptions import InvalidDocumentException, InvalidTemplateException
  File "/home/localstack/Repos/serverless-application-model/samtranslator/model/__init__.py", line 7, in <module>
    from samtranslator.intrinsics.resolver import IntrinsicsResolver
  File "/home/localstack/Repos/serverless-application-model/samtranslator/intrinsics/resolver.py", line 4, in <module>
    from samtranslator.intrinsics.actions import Action, GetAttAction, RefAction, SubAction
ImportError: cannot import name 'Action' from partially initialized module 'samtranslator.intrinsics.actions' (most likely due to a circular import) (/home/localstack/Repos/serverless-application-model/samtranslator/intrinsics/actions.py)

Expected result

With b3b6c79, the import does not fail (which I would expect).

Additional environment details

1. OS: Ubuntu 22.04, Python 3.10
2. If using the SAM CLI, sam --version: -
3. AWS region: -

[aahung]

Thanks for reporting. Looks like when we added type hints, it reveals that .models and .intrinsics are importing from each other. This should be avoided as .models.__init__ needs to focus on models not other behavior.

It isn't an issue if samtranslator.translator is directly imported. (as long as samtranslator.intrinsics.resolver is imported first it is not an issue).

[aahung]

List of modules that cannot be imported alone:

[aahung]

Fixed in https://github.com/aws/serverless-application-model/releases/tag/v1.60.1