fix(ec2): prevent deduplication of init command args

[Leo10Gama]

Issue # (if applicable)

Closes #26221

Reason for this change

Previously, using ec2.InitCommand.argvCommand() would remove some duplicate strings in the input array. This produces an incorrect command in the template, leading to unexpected behaviour.

Description of changes

An additional line was added to the deepMerge function that is called in the InitConfig.bindForType() method, which checks the key of the input array, preventing it from becoming a set (removing duplicates) if it is a list of commands.

Description of how you validated changes

A unit test was added to generate an AWS::CloudFormation::Init resource identical to the one reproduced in the issue. The test was run and failed before the changes were made, and following the changes in cfn-init.ts, the test passed.

Checklist

• My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

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

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[scanlonp]

Looking good with a couple small comments:

1. Let's switch the logic flow. It will be easier to understand with the specific cases handled first.
2. Do we have any current unit tests that test for de-duplication on non-command uses of the deep merge? If yes then we are all set. If not, we should probably put that case in to verify that this change stays scoped to the individual function we are targeting.

[Leo10Gama]

2. Do we have any current unit tests that test for de-duplication on non-command uses of the deep merge? If yes then we are all set. If not, we should probably put that case in to verify that this change stays scoped to the individual function we are targeting.

From what it seems like, this specific deepMerge is only used in this file by the bind functions, and it doesn't seem like it's used outside of this context. The only other deepMerge tests I can find are for a separate util that doesn't have to do with this function. But that is a good catch, I'll include tests to make sure the de-duping stays consistent.

[scanlonp]

My comments are addressed. I am good with the PR. Going to wait for a second review for approval.

[comcalvi]

can you make this:

ec2.InitSource.fromUrl('/tmp/foo', 'https://amazon.com/foo.zip'),
ec2.InitSource.fromUrl('/tmp/foo', 'https://amazon.com/foo.zip'),
ec2.InitSource.fromUrl('/tmp/foo', 'https://amazon.com/bar.zip'),
ec2.InitSource.fromUrl('/tmp/foo', 'https://amazon.com/bar.zip'),
ec2.InitSource.fromUrl('/tmp/bar', 'https://amazon.com/bar.zip'),
ec2.InitSource.fromUrl('/tmp/bar', 'https://amazon.com/bar.zip'),
ec2.InitSource.fromUrl('/tmp/bar', 'https://amazon.com/foobar.zip'),
ec2.InitSource.fromUrl('/tmp/bar', 'https://amazon.com/foobar.zip'),

or something like this so we can see whether the dedeup logic applies to both the first parameter and the second, or if it's just the second?

[Leo10Gama]

Good catch, will include some more dedup test values.

[comcalvi]

I approve of the 👻

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AWS CodeBuild CI Report

• CodeBuild project: AutoBuildv2Project1C6BFA3F-wQm2hXv2jqQv
• Commit ID: ce048a0
• Result: SUCCEEDED
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