Santize utf8 label values

[tivvit]

using #18

based on alicebob/asprom#42 - there is a description of the problem and the used solution is very similar - in this project, there is no wrapper function for metrics so I had to add it to more places.

[khaf]

Can we please have this PR decoupled from the #18? At this moment that changeset cannot not be merged.

[tivvit]

Yes I will prepare it. I am used to using modules, therefore it was more comfortable for me to do it like this, sorry for that

[tivvit]

done @khaf

[khaf]

Thank you, this is now much more clear to me. But I think there is no reason to pepper UTF8 validation all over the codebase.

There is a central function on the Observer that sends the requests to the server node and gets the result back. Those results are then sent to watchers to be parsed and used. That function stands in for the wrapper you are looking for.

You can add validations only in Observer.requestInfo#L205 by ranging over rawMetrics map and validating the values:

for range k, v := range rawMetrics {
  rawMetrics[k] = sanitizeLabelValue(v)
}

Is that what are looking for?

[tivvit]

thanks for the tip, this your proposed solution is much better

[khaf]

OK I merged this PR, but ended up rebasing it due to conflict with the other PR. Thank you for your efforts.