Version number does not appear in metrics

[MiniPierre]

Hello,

When querying the exporter metrics, it seems that there is a metric with build information but the version number is empty:

% curl -s http://xxx:xxx/metrics|grep unbound_exporter_build_info
# HELP unbound_exporter_build_info A metric with a constant '1' value labeled by version, revision, branch, goversion from which unbound_exporter was built, and the goos and goarch for the build.
# TYPE unbound_exporter_build_info gauge
unbound_exporter_build_info{branch="",goarch="amd64",goos="linux",goversion="go1.24.0",revision="unknown",tags="unknown",version=""} 1

Could you please have a look ?

Regards

[jsha]

The version field comes from here: https://github.com/prometheus/client_golang/blob/8179a560819f2c64ef6ade70e6ae4c73aecaca3c/prometheus/collectors/version/version.go#L36

Which gets it from here: https://github.com/prometheus/common/blob/v0.67.3/version/info.go#L27

The comment there says that those variables are filled at build time, but at least for Version I don't see how that happens.

Want to say more about your use case and why it's important to get the unbound_exporter version here? Are you perhaps looking for the unbound version?

[mcpherrinm]

I think the other users of this package set it via ldflags:

https://github.com/prometheus/node_exporter/blob/819c3705973b179c03896c2ab4d9af0bd7c35575/.promu.yml#L10-L15

So while we can get the vcs revision automatically, this code doesn't set the version.