feat!(exporter/blackbox): use required name attr instead label for target block

[hainenber]

PR Description

Which issue(s) this PR fixes

Fixes #5940

Notes to the Reviewer

Should this be a breaking change? I gave it some thoughts and unless we specify an interface to allow interchangeability (which is awkward, IMO), breaking change it is since label block is mandatory atm.

PR Checklist

• CHANGELOG.md updated
• Documentation added
• Tests updated
• Config converters updated

[rfratto]

I'm on PTO so I shouldn't be on GitHub, but I saw the recommendation for a breaking change in #5940 and wanted to offer an alternative:

Another way of doing this change that wouldn't be a breaking change is to have an optional attribute to override the target name, similar to the job_name attribute in prometheus.scrape:

target "my_target" { // default name: my_target 
  name = "my-target-with-custom-characters" // override default 
  ... 
}

cc @erikbaranowski

[hainenber]

Oh that's a good alternative right there. But I couldn't help but wonder if this is some kind of debt that can be cleared before v1.0.0 😄

If Erik's cool with this, I'm cool as well.

[ptodev]

If we go ahead with a breaking change, it will need to be documented in docs/sources/flow/release-notes.md, which corresponds to Release notes for Grafana Agent Flow.

My personal preference would be to just do it as a breaking change, because this seems very minor. However, we should get some team consensus on this before proceeding with a specific approach.

[erikbaranowski]

looks great, thanks for taking care of this!

I'll have a follow up PR likely to address some similar components we have identified.

[erikbaranowski]

My preference is to go with the breaking change before 1.0 instead of leaving a potential stumbling block behind. If someone uses a label they may waste time figuring out why job-name is invalid.

[erikbaranowski]

I'm poking at the go test issue to see what is going on

[hainenber]

The latest one is A-OK now, the CI complained previously since I added tab instead of spaces :D

[erikbaranowski]

A totally unrelated test had failed in the CI but I can't recreate it locally. I restarted the CI and hopefully it doesn't keep happening.