Integrate request/response headers and body into OpenTelemetry traces

[andreasteich]

Currently, OpenTelemetry tracing in Deno captures metadata about HTTP requests but does not include request/response headers or bodies. To improve observability and debugging, it would be useful to optionally integrate this information into traces.

Expected Behavior

• HTTP request headers should be included in traces.
• HTTP response headers should be included in traces.
• Optionally, request and response bodies should be captured (with appropriate safeguards to prevent logging sensitive data).
• Configurable filtering should be available to exclude specific headers or payloads.

Actual Behavior

• OpenTelemetry traces currently do not include request/response headers or bodies.

Use Cases

• Debugging distributed applications by providing full request/response context in traces.
• Analyzing API behavior and performance bottlenecks.
• Enhancing monitoring by correlating headers (e.g., correlation IDs) across services.

Proposed Solution

• Modify the OpenTelemetry instrumentation in Deno to capture request/response headers.
• Introduce an opt-in mechanism for capturing request/response bodies.
• Implement filtering mechanisms to prevent sensitive data exposure.
• Ensure performance impact is minimal by making body capture optional.

Would love to hear thoughts on feasibility and potential concerns regarding security and performance!