Regex parse labels?

[wrouesnel]

Is it possible (or could it be made possible) to format legend labels with regex's applied to the actual time series? Mostly so long instance-name's can be filtered down to the small chunk of relevant data for display.

i.e. server.domain.com:9100 => server

[grobie]

You can use one of the available filters promdash provides: hostname or the generic regex. Legend string example:

{{ instance | hostname }}

These should have been documented ages ago, you can follow prometheus/docs#57 for updates.

[wrouesnel]

Trying out a few of those, they don't seem to work at the moment - i.e.
instance = "host.example.org:9100" with the filter {{ instance | hostname }} just yielded a blank entry.

And regex matching only seems to do simple string substitutions without punctuation - adding periods (.) at any point broke the parsing of the label.

[grobie]

Oh, you uncovered a compatibility problem with the new instance label. Prometheus >= 0.11.0 dropped the scheme and path from the values. I'm confused why it hasn't hit us (soundcloud) yet.

Anyway, the hostname filters should probably be changed to work with an hostname:port format as well. a.href rejects values without a scheme it seems.

I was able to replicate your observations around the regex filter. I was unable to execute the first test for regex. @stuartnelson3 any ideas why the test behavior seems to differ here?

PRs welcome as usual :D I might take a look tomorrow otherwise.

[stuartnelson3]

the issue with the regex filter lies in variable_interpolator.js. that whole file needs to be replaced.