The lack of lookahead is a pain in Go's regexp engine, and this cascades to the various apps that use it, such as Prometheus and Kubernetes. Mainly, it means i

The lack of lookahead is a pain in Go's regexp engine, and this cascades to the various apps that use it, such as Prometheus and Kubernetes. Mainly, it means it's super awkward — arguably so awkward it's completely impractical, because the result ends up being unreadable and probably slow — to do negative matching, i.e. exclusion.