🐛 fix: fully bypass CloudFormation when -skip-cloudformation-creation is set

[SAY-5]

What type of PR is this?

/kind bug

What this PR does / why we need it:

-skip-cloudformation-creation only guarded the createCloudFormationStack call. Two follow-on calls assumed the stack existed in the current region:

• ensureStackTags (suite.go:155) calls CloudFormation:DescribeStacks and fails with ValidationError: Stack ... does not exist when the stack lives in a different region (CloudFormation is regional).
• newUserAccessKey (aws.go:877) calls IAM:ListAccessKeys for the bootstrap user. If the existing stack was deployed without BootstrapUser.Enable = true, the user does not exist; the error from ListAccessKeys was being silently discarded (keyOuts, _ := ...) and the next loop iteration nil-derefs keyOuts.AccessKeyMetadata.

This PR moves both calls inside the existing if !SkipCloudFormationCreation guard. When skipping, it derives BootstrapAccessKey from the calling session's resolved credentials so downstream consumers (encodeCredentials, BootstrapUserAWSSession, EnsureServiceQuotas, etc.) keep working. It also surfaces the previously discarded ListAccessKeys error so any future failure produces a real diagnostic instead of a nil-pointer panic.

Which issue(s) this PR fixes:
Fixes #5944

Special notes for your reviewer:

The skip path assumes the calling session uses long-lived IAM credentials (which is the typical setup when the CF stack has been pre-deployed). iamtypes.AccessKey has no SessionToken field, so STS temporary credentials would lose their token; this matches the behavior of NewAWSSessionWithKey already in the file.

AI Usage:

Claude Code (Sonnet/Opus) assisted with locating the affected call sites and drafting the patch. I reviewed every line before commit, validated the control flow against the issue reporter's repro, and confirmed go build -tags=e2e ./test/e2e/shared/... and go vet pass cleanly.

Checklist:

• squashed commits
• includes documentation
• includes AI generated content
• includes emoji in title
• adds unit tests
• adds or updates e2e tests

Release note:

Fix `-skip-cloudformation-creation` so it also bypasses the CloudFormation `DescribeStacks` tag check and the bootstrap user access-key creation, allowing e2e tests to run against a pre-deployed stack in a different region or one without `BootstrapUser` enabled. Also surface a previously discarded `ListAccessKeys` error that masked the real failure as a nil-pointer panic.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: SAY-5 / name: Sai Asish Y (1ff67fe, 28482fa)
• ✅ login: raykrueger / name: Ray Krueger (28482fa)

[k8s-ci-robot]

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[k8s-ci-robot]

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[k8s-ci-robot]

Hi @SAY-5. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work.

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[SAY-5]

CLA pending, will link the commit email to the GitHub account shortly to clear EasyCLA.

[richardcase]

/ok-to-test

[raykrueger]

I opened this issue, and I do actually have code for this you can grab from as neeed.
https://github.com/raykrueger/cluster-api-provider-aws/tree/fix/skip-cloudformation-credential-fallback

I never opened the PR because I've been using it as a local cherry-pick patch, and haven't sat down to make it into a PR

[SAY-5]

@raykrueger thanks, pulled the runtime iamUserExists probe and the SessionToken-preserving credential encode from your branch (credited in the commit message). Switched my flag-based fallback over to the runtime check so the path also works when -skip-cloudformation-creation is set but the bootstrap user happens to exist.

[richardcase]

/retest

[richardcase]

/test ?

[richardcase]

/test pull-cluster-api-provider-aws-e2e-eks
/test pull-cluster-api-provider-aws-e2e

[SAY-5]

The eks job failed on a 40 minute provision timeout in the upgrade-policy spec (WaitForClusterToProvision), not in the bootstrap path this PR touches; the suite setup and the other 12 specs passed. Looks like an infra flake.

/retest

[damdo]

/test pull-cluster-api-provider-aws-e2e-eks

[k8s-ci-robot]

@SAY-5: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-cluster-api-provider-aws-e2e-eks	28482fa	link	false	/test pull-cluster-api-provider-aws-e2e-eks

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

Details

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository. I understand the commands that are listed here.