Measure DNS lookup times for HTTP requests

[jonboydell-massive]

I don't see the http_req_looking_up metric in the std output and if I try to create a Trend recording myTrend.add(res.timings.looking_up); I get a series of 0s in the output of that Trend.

I'm using v0.24.0

[na--]

Thanks for reporting this and sorry for the confusion - the documentation was wrong, it seems like it hadn't been updated after the tracking of DNS lookup times was removed in k6 v0.13 by this commit.

I don't know the full details about what prompted the removal of the metric, though #41 points to the possibility that it was also part of the http_req_duration meta-metric and skewed it too much. In any case, we plan to bring it back, and improve DNS support in general. I'll leave this issue open as a tracking point for the DNS metric measurements specifically, and here are the other DNS-related issues that we want to fix:

• Unexpected DNS caching #726 for DNS caching issues - fixing this should happen before the current metrics issue, since the unexpected DNS caching will skew any metrics
• DNS round-robin ignored, always uses the same host #738 for ignoring DNS round-robin
• Feature request: DNS test library #851 for actually exposing DNS resolving as a k6 JS API and measuring all DNS-related metrics

[MattDodsonEnglish]

This response metric was still documented in the API. It said "currently unavailable", but nevertheless at least one user tried to use it anyway (that user was me).

I've removed the documentation. If this issue is ever fixed, we can redocument it.

grafana/k6-docs@26e5109