EmfMetricPublisher class added

[Fred1155]

Motivation and Context

The existing CloudWatchMetricPublisher has limitations when used with AWS Lambda functions. When current implementation be applied to lambda functions, it can results in metrics being lost when the lambda function terminates before the scheduled batch upload. EMF allows metrics to be published through CloudWatch Logs using a structured JSON format, which CloudWatch automatically processes to extract and publish metrics. The proposed EMFMetricPublisher will convert SDK metric collections into EMF-formatted log entries, leveraging Lambda's as well as other execution environment that has built-in integration with cloudwatch logs such as ECS.

Modifications

Add a new metric publisher that transforms an metricCollection to a list of emf format Strings and publish it to CouldWatch using cloudwatch agents

Testing

1. Unit test covering different cases of metricCollection in convertMetricCollectionToEMF method
2. End to End test (In process)

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• I have read the CONTRIBUTING document
• Local run of mvn install succeeds
• My code follows the code style of this project
• My change requires a change to the Javadoc documentation
• I have updated the Javadoc documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed
• I have added a changelog entry. Adding a new entry must be accomplished by running the scripts/new-change script and following the instructions. Commit the new file created by the script in .changes/next-release with your changes.
• My change is to implement 1.11 parity feature and I have updated LaunchChangelog

License

• I confirm that this pull request can be released under the Apache 2 license

[zoewangg]

Left some high level comments, still reviewing the implementation

[zoewangg]

Can we try markdown for javadoc?

https://docs.oracle.com/en/java/javase/23/javadoc/using-markdown-documentation-comments.html#GUID-0E4D6135-AAE9-4641-8427-CEE7F65E4F6E

[zoewangg]

We should use @snippet for code sample for javadoc

https://github.com/aws/aws-sdk-java-v2/blob/master/docs/design/APIReference.md#style-guideline

[zoewangg]

We should use dependency injection for testing if we need to mock a dependency. eg: https://github.com/aws/aws-sdk-java-v2/blob/master/services-custom/s3-transfer-manager/src/main/java/software/amazon/awssdk/transfer/s3/internal/GenericS3TransferManager.java#L121

[zoewangg]

Consider using parameterized tests if we are just testing with different input

[sonarqubecloud]

Quality Gate failed

Failed conditions
2 Security Hotspots
3.5% Duplication on New Code (required ≤ 3%)

See analysis details on SonarQube Cloud

[zoewangg]

Is this correct? It seems this CloudWatchMetrics only has one object

[Fred1155]

I think so. In the example https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/CloudWatch_Embedded_Metric_Format_Specification.html, CloudWatchMetrics should have one object, because we only have one namespace and one set of dimensions

[zoewangg]

We don't have to change it now, but we should discuss it in API surface area review. Should we rename it to emf-metric-logger, since technically it's not publishing metrics?