feat(ecs): warning when creating a service with the default minHealthyPercent

[MarrickLip]

Issue

Closes #31705

Reason for this change

CDK overrides the default value of 100% used by CloudFormation's AWS::ECS::Service and the CreateService API. This allows the number of running tasks to drop by up to 50% during deployments and Fargate maintenance etc.

This is an unsafe default for services which must support a consistent load e.g. handle web traffic via an ALB.

Description of changes

A warning appears when the default value is implicitly used. CloudFormation's default is overridden in three different places so multiple warnings are added:

• BaseService emits @aws-cdk/aws-ecs:minHealthyPercent when minHealthyPercent is undefined
• Ec2Service emits @aws-cdk/aws-ecs:minHealthyPercentDaemon when daemon is true and minHealthyPercent is undefined
• ExternalService emits @aws-cdk/aws-ecs:minHealthyPercentExternal when minHealthyPercent is undefined

At most one warning appears due to the way the CloudFormation's default is overidden.

README.md has been updated for aws_ecs and aws_ecs_patterns to ensure these examples don't trigger this warning.

Description of how you validated changes

Unit tests have been added to ensure the warnings appear are there when they should be and not when they shouldn't.

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.

[MarrickLip]

The pull request linter fails with the following errors:

❌ Features must contain a change to an integration test file and the resulting snapshot.

PRs must pass status checks before we can provide a meaningful review.

If you would like to request an exemption from the status checks or clarification on feedback, please leave a comment on this PR containing Exemption Request and/or Clarification Request.

Exemption Request: warning doesn't change synthesized CloudFormation stacks so new integration tests not required.

[godwingrs22]

@MarrickLip Thanks for your contribution. LGTM.

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

[mergify]

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[godwingrs22]

@mergify update

[mergify]

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Pull request has been modified.

[aws-cdk-automation]

AWS CodeBuild CI Report

• CodeBuild project: AutoBuildv2Project1C6BFA3F-wQm2hXv2jqQv
• Commit ID: a50f5b3
• Result: SUCCEEDED
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[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).

[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).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.52%. Comparing base (c57debb) to head (a50f5b3).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #31738   +/-   ##
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  Coverage   81.52%   81.52%           
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  Files         222      222           
  Lines       13715    13715           
  Branches     2417     2417           
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  Hits        11181    11181           
  Misses       2254     2254           
  Partials      280      280           

Flag	Coverage Δ
suite.unit	81.52% <ø> (ø)

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

Components	Coverage Δ
packages/aws-cdk	80.97% <ø> (ø)
packages/aws-cdk-lib/core	82.09% <ø> (ø)

[godwingrs22]

@Mergifyio update

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update

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