Add additional tag/log to rules Manager Eval trace span.

[cstyan]

Adds a tag to the span that says whether the evaluation succeeded, and a log line to the span with the error message in the result of failure.

Signed-off-by: Callum Styan callumstyan@gmail.com

[roidelapluie]

should we simply set the "standard" error=true on failed evaluations?

[cstyan]

Fine by me, the name of the tag isn't support important to me and if there's a standard I'm not aware of it. However I do need both the status (failed/succeeded) and the error message log.

[roidelapluie]

Fine by me, the name of the tag isn't support important to me and if there's a standard I'm not aware of it. However I do need both the status (failed/succeeded) and the error message log.

As the jaeger UI offers error=true in its UI exemples by default I have always assumed it was kinda standard

[roidelapluie]

error=true is detected by jaeger ui as well and displayed with a red tag.

[cstyan]

error=true is detected by jaeger ui as well and displayed with a red tag. yep, you're right, I only just learned about this the day I opened this PR, @roidelapluie PTAL