In the current version of EnvFilter, the directive [span{field=}] does not work as expected.
The directive [span{field}] filter for all spans span that have a field field while the directive [{field=a}] filters for all spans span where the field field has the value a. In contrast, the directive [span{field=}] filters only for spans span. IMHO this is unexpected behavior.
Solution
Digging into the code for parsing Directives the regex for field matches didn't consider the field= case. This PR changes the regex so that field= is interpreted as a match on an empty string.
With regex enabled this means that now field= behaves like field.
Alternative solution
Instead of accepting the field= directive, it could trigger an error instead invalidating the whole directive.
Motivation
In the current version of
EnvFilter, the directive[span{field=}]does not work as expected.The directive
[span{field}]filter for all spansspanthat have a fieldfieldwhile the directive[{field=a}]filters for all spansspanwhere the fieldfieldhas the valuea. In contrast, the directive[span{field=}]filters only for spansspan. IMHO this is unexpected behavior.Solution
Digging into the code for parsing
Directives the regex for field matches didn't consider thefield=case. This PR changes the regex so thatfield=is interpreted as a match on an empty string.With regex enabled this means that now
field=behaves likefield.Alternative solution
Instead of accepting the
field=directive, it could trigger an error instead invalidating the whole directive.