ecr: allow `fromLookup` method to return dummy repository without error if target repository was not found

[go-to-k]

Describe the feature

The fromLookup method causes an error if the target repository was not found. However it would be also good not to cause an error and to return dummy value in that case.

Now, with the PR merged in aws-cdk-cli (aws-cdk@v2.1006.0), we can ignore errors and return dummy value with mustExist option in CC API Provider.

Use Case

If the target repository exists in the AWS account, it will be used, and if not, a new repository can be created in the stack.

Proposed Solution

• Added the mustExist option in RepositoryLookupOptions.
  • Pass it to mustExist for ContextProvider.getValue

Other Information

No response

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

CDK version used

2.187.0

Environment details (OS name and version, etc.)

Mac

[pahud]

Hi @go-to-k,

Thanks for submitting this feature request!

I understand the use case: you want Repository.fromLookup() to optionally return a dummy or placeholder object when the target ECR repository doesn't exist, instead of causing a synthesis error. This would allow for cleaner conditional logic in stacks where you might want to create a repository only if it doesn't already exist.

Your proposed solution of adding a mustExist flag to RepositoryLookupOptions seems like the right approach. As you noted, the underlying context provider mechanism in the AWS CDK CLI (CC_API_PROVIDER) was updated in aws/aws-cdk-cli#211 (v2.1006.0+) to support this mustExist behavior.

The necessary change involves updating the Repository.fromLookup implementation in packages/aws-cdk-lib/aws-ecr/lib/repository.ts to:

1. Add the mustExist option to RepositoryLookupOptions.
2. Pass this option down to the ContextProvider.getValue call.
3. Handle the potential dummy response when mustExist is false and the repository isn't found.

This looks like a valuable enhancement. I am marking this a p2 FR and we welcome your PRs as always. :)

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