Example Kubernetes port annotation does not use port number

[bboreham]

In this line which is given as an example of annotation usage,

- source_labels: [__address__, __meta_kubernetes_service_annotation_example_io_scrape_port]
  action: replace
  regex: ([^:]+)(?::\d+)?;(\d+)
  replacement: $1:$2
  target_label: __address__

I am puzzled that the replacement is $1:$2; I expect it to be $1:$3 so that the port number specified in the annotation is used.

For instance I see a similar line matching my expectation here.

[simonpasquier]

This is because the second group ((?::\d+)) isn't captured (eg it starts with (?:).

[bboreham]

Ooh. TIL.