improv(tracer): set AWS_XRAY_CONTEXT_MISSING to IGNORE_ERROR when no value is set

[dreamorosi]

Summary

Changes

Please provide a summary of what's being changed

This PR updates the Tracer utility to set the AWS_XRAY_CONTEXT_MISSING environment variable to IGNORE_ERROR by default.

This change has been made in response to customers adopting features that rely on top-level await and finding the error logs produced by X-Ray SDK not useful.

The X-Ray SDK for Node.js was not designed with this feature in mind, and by default it logs an error when a code path attempts to send trace data outside of the context of a request.

This is because without the request context, there's no X-Ray Trace ID, and so the SDK is unable to establish the lineage of a segment/span.

In many cases this is a desired behavior (although I'd have preferred it was a warning rather than an error log), however now that making async operations during the init phase is possible, it's not uncommon to make outbound http requests or use the AWS SDK to retrieve data or perform setup operations.

In those cases, the auto instrumentation features of Tracer (& the underlying X-Ray SDK) attempt to create a segment for these operations but don't find one because these tasks are run during the init phase, and thus outside of the context of a request.

The change has been made with backwards compatibility in mind, to an extent. Before setting the value we check if the env variable is already set and if so, we leave it as-is.

I believe this is a good middle ground between furthering our features and maintaining flexibility.

Please add the issue number below, if no issue is present the PR might get blocked and not be reviewed

Issue number: closes #2406

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[leandrodamascena]

For more coverage and to make sure that if there are any changes in the future, they will be detected, you should add a test (EnvVarTest) or is this too much? WDYT?

Requesting changes to hear from you.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[dreamorosi]

Yea good point - I added it elsewhere because that one you linked is for reading from the env var, but I think it's the same.