(core): Python package aws-cdk-lib is missing the __version__ attribute

[mwebber]

Describe the bug

The normal convention in the Python world is for pip-installed packages to report their version number via the __version__ attribute. However, aws_cdk does not currently support this, so code cannot introspect its environment to check whether, for example, the expected version of aws_cdk is being used.

Expected Behavior

I expected it to work in the same was as most other Python packages, e.g

# this works
>>> import boto3
>>> boto3.__version__
'1.34.3'

Thus, I should be able to do

# this doesn't work, but should
>>> import aws_cdk
>>> aws_cdk.__version__
'2.113.0'

Current Behavior

# current behavior
>>> import aws_cdk
>>> aws_cdk.__version__
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: module 'aws_cdk' has no attribute '__version__'

Reproduction Steps

This can be tested in a stand-alone environment easily enough

Show that version not defined

python3
import aws_cdk
print(aws_cdk.__version__)
# AttributeError thrown here
exit()

The version is available in the package metadata, it's just not exposed as a python attribute

pip show aws-cdk-lib
Name: aws-cdk-lib
Version: 2.113.0
Summary: Version 2 of the AWS Cloud Development Kit library
Home-page: https://github.com/aws/aws-cdk
Author: Amazon Web Services
Author-email:
License: Apache-2.0
Location: /xxx/.venv/lib/python3.11/site-packages
Requires: aws-cdk.asset-awscli-v1, aws-cdk.asset-kubectl-v20, aws-cdk.asset-node-proxy-agent-v6, constructs, jsii, publication, typeguard

Possible Solution

No response

Additional Information/Context

The following workaround can be used to get what appears to be the CDK version, but it's clearly an irregular approach.

from aws_cdk._jsii import __jsii_assembly__ as jsii_assembly
print("*** have", jsii_assembly.version)

CDK CLI Version

2.113.0 (build ccd534a)

Framework Version

No response

Node.js Version

v20.10.0

OS

macOS 13.4.1

Language

Python

Language Version

Python (3.11.6)

Other information

No response

[pahud]

Makes sense. Thank you for the feature request.

[mwebber]

@pahud After further investigation, I found pallets/flask#5230, which suggests that __version__ is superseded by importlib.metadata..

This already works:

from importlib import metadata
[x.version for x in metadata.distributions() if x.name=='aws-cdk-lib'][0]
'2.113.0'

so maybe this ticket can be closed as unnecessary.

[github-actions]

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