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Have the global Propagators default to a no-op instance. #721

12 changes: 7 additions & 5 deletions specification/context/api-propagators.md
Original file line number Diff line number Diff line change
Expand Up @@ -249,11 +249,13 @@ Required arguments:
Implementations MAY provide global `Propagator`s for
each supported `Propagator` type.

If offered, the global `Propagator`s should default to a composite `Propagator`
containing the W3C Trace Context Propagator and the Correlation Context `Propagator`
specified in [api-correlationcontext.md](../correlationcontext/api.md#serialization),
in order to provide propagation even in the presence of no-op
OpenTelemetry implementations.
If offered, the global `Propagator`s MUST default to a no-op instance.
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@carlosalberto in this PR are you advocating for code cleanliness or scenario? This may be the root of the misunderstanding. I think myself, @yurishkuro and @bogdandrutu all advocating for a long term goal of having context ambiently propagated everywhere. It may be that the extensions you mentioned below would be the mechanism of this enablement, but I believe this context should be everywhere.

For example, to explain better what happens in .NET. - there is no context propagation when nothing is enabled. But even smaller level of logging enablement (which is default) will enable context propagation. We clearly recognize some people want to turn it off, But default is ON.

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Sorry for the lack of context. A week ago, in the Specification SIG call (at least @bogdandrutu was there), we came to an agreement on having the API with no-op Propagators by default (.Net will keep its current behavior, given the specific needs of how it's used in the .Net framework and how things are instrumented by default).

But even smaller level of logging enablement (which is default) will enable context propagation

Oh, actually this is what I tried to convey when I mentioned OpenTelemetry extensions (same in spirit, although not quite the same).

cc @bogdandrutu @yurishkuro

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In order to override the default value, an call to
[Set Global Propagator](#set-global-propagator) MUST be done
by either SDK implementations, OpenTelemetry extensions or final application code.
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Note: OpenTelemetry .NET is an exception to this rule as his global
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`Propagator`s default to a set of specific `Propagator`s, including `TraceContext`.
Comment on lines +277 to +278
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It would be nice to reference the .NET documentation giving more details on that.

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@reyang @SergeyKanzhelev Any 'official' documentation we could mention here for the .NET case?

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### Get Global Propagator

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