Invert `regexp` operator

[IgnacioHeredia]

Proposal

I want to have a constraint that makes the job avoid clients with batch (substring) in their metadata tags (string) field.
The issue is loosely related to #6610.

test, batch, demo --> avoid
test, demo --> fine

Attempted Solutions

1. I've tried this:

     constraint {
       attribute = "${meta.tags}"
       operator  = "regexp"
       value     = "^(?!.*batch).*$"
     }

   But it looks the Go engine does not support negative lookaheads for performance reasons (ref).

2. One option would be to negate the regexp operator, but regexp_not does not seem to exist in Nomad.

Is there any way to achieve this in Nomad? I've ended up moving batch to a different individual metadata field, but I would like to know if it's possible just in case for next time.

Thanks!

[jrasell]

Hi @IgnacioHeredia and thanks for raising this issue. I can see how useful a feature in this area could be, so I'll mark this for roadmapping.