fix(cli): failure to get credentials when session token is not set

[otaviomacedo]

In Node.js, if you assign undefined to an environment variable, that variable ends up having the string "undefined".

If we are using IAM user credentials, AWS_SESSION_TOKEN should not be set, but because we were not handling this edge case, it was getting assigned an invalid value:

Welcome to Node.js v22.9.0.
Type ".help" for more information.
> process.env.AWS_SESSION_TOKEN || process.env.AMAZON_SESSION_TOKEN
undefined
> process.env.AWS_SESSION_TOKEN = process.env.AWS_SESSION_TOKEN || process.env.AMAZON_SESSION_TOKEN
undefined
> process.env.AWS_SESSION_TOKEN
'undefined'

Closes #32120.

Checklist

• My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

---

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

[aws-cdk-automation]

The pull request linter has failed. See the aws-cdk-automation comment below for failure reasons. If you believe this pull request should receive an exemption, please comment and provide a justification.

A comment requesting an exemption should contain the text Exemption Request. Additionally, if clarification is needed add Clarification Request to a comment.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.15%. Comparing base (339fed1) to head (eee2a95).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #32134   +/-   ##
=======================================
  Coverage   77.14%   77.15%           
=======================================
  Files         105      105           
  Lines        7163     7165    +2     
  Branches     1311     1312    +1     
=======================================
+ Hits         5526     5528    +2     
  Misses       1457     1457           
  Partials      180      180           

Flag	Coverage Δ
suite.unit	77.15% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
packages/aws-cdk	77.15% <100.00%> (+<0.01%)	⬆️

[rix0rrr]

Why don't we do this inside the if that checks for id and key?

Why do we need to do this at all, anyway? Is it because AMAZON_ACCESS_KEY_ID is no longer supported, and it must be AWS_ACCESS_KEY_ID?

[otaviomacedo]

Why don't we do this inside the if that checks for id and key?

Sure.

Why do we need to do this at all, anyway?

Because we want to keep it backward compatible and still support AMAZON_ACCESS_KEY_ID, but the SDK only reads from AWS_ACCESS_KEY_ID.

[aws-cdk-automation]

➡️ PR build request submitted to test-main-pipeline ⬅️

A maintainer must now check the pipeline and add the pr-linter/cli-integ-tested label once the pipeline succeeds.

✅ Updated pull request passes all PRLinter validations. Dismissing previous PRLinter review.

[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

[aws-cdk-automation]

AWS CodeBuild CI Report

• CodeBuild project: AutoBuildv2Project1C6BFA3F-wQm2hXv2jqQv
• Commit ID: eee2a95
• Result: SUCCEEDED
• Build Logs (available for 30 days)

Powered by github-codebuild-logs, available on the AWS Serverless Application Repository

[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

[github-actions]

Comments on closed issues and PRs are hard for our team to see.
If you need help, please open a new issue that references this one.