Incompatibility between the W3C Baggage spec version used in the Resource spec and the Baggage spec

[lgfa29]

What are you trying to achieve?

When defining the value for the OTEL_RESOURCE_ATTRIBUTES environment variable, the resource specification links to the version fdc7a5c4f4a31ba2a36717541055e551c2b032e4 of the W3C Baggage format, while the OpenTelemetry Baggage specification doesn't specify any particular version.

This causes an incompatibly in how baggage values are handled between the two specifications because the latest W3C Baggage spec defines that:

Any characters outside of the baggage-octet range of characters MUST be percent-encoded.
https://w3c.github.io/baggage/#value

But the version used by the Resource spec doesn't have this requirement.

The effect of this difference is that, when using a library that follows the OpenTelemetry Baggage spec (such as go.opentelemetry.io/otel/baggage) to generate the value for the OTEL_RESOURCE_ATTRIBUTES environment variable, the baggage values will be encoded by the library but not decoded by the SDK.

Additional context.

@MrAlias noticed this difference in open-telemetry/opentelemetry-go#2963.

[jsuereth]

It looks like we should take the time to update our specification to account for changes in the Baggage specification. Feel free to open a PR to address this.

[lgfa29]

Thank you @jsuereth, I opened #2670 to update the spec 🙂