Honor DD_MERGE_XRAY_TRACES from Function Environment

BlissfulDarkness commented 2 years ago

What does this PR do?

When using the default values, if X-Ray Tracing is being managed separately from the DataDog Serverless Macro, keep the existing value.

This at least partially resolves #69 by keeping the Environment Variable from the template if you ONLY enable DataDog Tracking through the Macro, leaving X-Ray Tracing to be unaffected

Motivation

This is blocking our use of the newer version of the Datadog Serverless Macro

Testing Guidelines

Updated tracing.spec.ts with an example resource based on the actual resource generated in CloudFormation. Added unit test for this specific scenario.

Additional Notes

Types of changes

[ ] Bug fix
[ ] New feature
[ ] Breaking change
[ ] Misc (docs, refactoring, dependency upgrade, etc.)

Check all that apply

[ ] This PR's description is comprehensive
[ ] This PR contains breaking changes that are documented in the description
[ ] This PR introduces new APIs or parameters that are documented and unlikely to change in the foreseeable future
[ ] This PR impacts documentation, and it has been updated (or a ticket has been logged)
[X] This PR's changes are covered by the automated tests
[ ] This PR collects user input/sensitive content into Datadog

tianchu commented 2 years ago

See https://github.com/DataDog/datadog-cloudformation-macro/issues/69#issuecomment-1155708407

tianchu commented 2 years ago

Closing in favor of what's proposed in https://github.com/DataDog/datadog-cloudformation-macro/issues/69#issuecomment-1155708407.

DataDog / datadog-cloudformation-macro