resource/aws_iot_policy: Delete oldest policy version when max number of versions is reached

[jeandek]

• This change adds a function call that deletes the oldest non-default IoT policy version when the creation of a new version would result in a breach of the max number of versions (5).
• Note that due to a bug in the Go SDK (+ CLI + Python SDK), all versions of the policy have the same creation date. Thus, I could not use it to find the oldest version (like in the aws_iam_policy resource) and I decided to use the version IDs instead.

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Closes #9540.
Closes #30314.
Closes #24979.

Release note for CHANGELOG:

resource/aws_iot_policy: Prune oldest non-default version of IoT policies when required to create a new version

Output from acceptance testing:

make testacc TEST=./aws TESTARGS='-run=TestAccAWSIoTPolicy'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./aws -v -parallel 20 -run=TestAccAWSIoTPolicy -timeout 120m
=== RUN   TestAccAWSIoTPolicy_basic
=== PAUSE TestAccAWSIoTPolicy_basic
=== RUN   TestAccAWSIoTPolicy_invalidJson
=== PAUSE TestAccAWSIoTPolicy_invalidJson
=== RUN   TestAccAWSIoTPolicy_update
=== PAUSE TestAccAWSIoTPolicy_update
=== CONT  TestAccAWSIoTPolicy_basic
=== CONT  TestAccAWSIoTPolicy_update
=== CONT  TestAccAWSIoTPolicy_invalidJson
--- PASS: TestAccAWSIoTPolicy_invalidJson (10.78s)
--- PASS: TestAccAWSIoTPolicy_basic (22.19s)
--- PASS: TestAccAWSIoTPolicy_update (109.06s)
PASS
ok      github.com/terraform-providers/terraform-provider-aws/aws       109.101s

[jeandek]

The pull request's code is now working as expected and contains a proper acceptance test. However, it's rather long to run. This is most likely due to the number of steps in the test case, since we have to update the resource 6 times to replicate the issue/fix...

If there's some way to optimize it, I'm all ears and willing to learn !

[yerida]

When is this issue released?

[jeandek]

I'm not sure. I haven't had any feedback for over 6 months...

I'm not doing IoT work anymore, so I'm in no hurry I guess.

[zhelding]

Pull request #21306 has significantly refactored the AWS Provider codebase. As a result, most PRs opened prior to the refactor now have merge conflicts that must be resolved before proceeding.

Specifically, PR #21306 relocated the code for all AWS resources and data sources from a single aws directory to a large number of separate directories in internal/service, each corresponding to a particular AWS service. This separation of code has also allowed for us to simplify the names of underlying functions -- while still avoiding namespace collisions.

We recognize that many pull requests have been open for some time without yet being addressed by our maintainers. Therefore, we want to make it clear that resolving these conflicts in no way affects the prioritization of a particular pull request. Once a pull request has been prioritized for review, the necessary changes will be made by a maintainer -- either directly or in collaboration with the pull request author.

For a more complete description of this refactor, including examples of how old filepaths and function names correspond to their new counterparts: please refer to issue #20000.

For a quick guide on how to amend your pull request to resolve the merge conflicts resulting from this refactor and bring it in line with our new code patterns: please refer to our Service Package Refactor Pull Request Guide.

[ewbankkit]

@jeandek Thanks for the contribution 🎉 👏.
This functionality has been included in #34329.

[github-actions]

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