istio: Mismatch of istio_build gauge metrics description

Is this the right place to submit this?

• This is not a security vulnerability or a crashing bug
• This is not a question about how to use Istio

Bug Description

The istio_build gauge metric is being reported by various Istio components.

With 1.18 we sometimes experience errors collecting these metrics by a prometheus exporter because of a mismatch of the existence/empty of the HELP text for the metric (gauge has help "Istio component build info" but should have "") in different components. I think we hit this error in cases when the metric is first collected (and therefore initialized) from the sidecars.

Specifically istiod reports something like:

# HELP istio_build Istio component build info
# TYPE istio_build gauge
istio_build{component="pilot",tag="1.18.1-30-gba3555469c05"} 1

while the stats filter of the sidecars reports the metric without HELP text:

# TYPE istio_build gauge
istio_build{component="proxy",tag="1.18-dev"} 1

We experienced this issue with 1.18.0-1.18.3 but I think it can potentially appear in 1.19+ as well.

Version

1.18.3

Additional Information

No response