Proposal to modify the group tag syntax.

[ppcano]

The current syntax of the system tag group is not fully documented and its syntax may not be intuitive.

Given the following script:

import http from "k6/http";
import { check, group } from "k6";


export default function() {
 group("mainGroup", function() {
   http.get("https://loadimpact.com");

   group("nestedGroup", function() {
     http.get("https://test.loadimpact.com");
   });
 });
};

It will generate tags like:

{"type":"Point","tags":{"group":"::mainGroup"}},"metric":"http_reqs"...}
{"type":"Point","tags":{"group":"::mainGroup::nestedGroup"}},"metric":"http_reqs"...}

{"type":"Point", "tags":{"group":"::mainGroup"}},"metric":"group_duration"...}
{"type":"Point", "tags":{"group":"::mainGroup::nestedGroup"}},"metric":"group_duration"...}

The current syntax is that group tags are always prepended with ::. A threshold on a non-nested group must be configured:

export let options = {
  thresholds: {
    "group_duration{group:::mainGroup}": ["p(95)<1000"],
  }
}

The syntax of 👆 is not intuitive. I think :: is a good symbol for referencing a nested group, but the first group may not be perceived as a nested group.

My proposal is to remove :: from non-nested groups, then users could define thresholds as:

export let options = {
  thresholds: {
    "group_duration{group:mainGroup}": ["p(95)<1000"],
    "group_duration{group:mainGroup::nestedGroup}": ["p(95)<1000"],
  }
}

[na--]

Hmm while I don't like the :: separator, I don't think we can change it now, it would be a major breaking change. Besides, we can fix the issue from the other side, by changing the threshold syntax so it's not depending on the colon for equality, i.e. get rid of key:value expressions for submetrics.

We want to do that for other reasons as well, the current submetric definition is quite inflexible. See #1443 and #1313 for more details. And whatever that syntax ends up being, if we have something like group === "::mainGroup::nestedGroup", it looks much better than the current ::: mess. So, I'll make a note in #1443 about this, and I think we should close this issue and #1119. @imiric @mstoykov, thoughts?

[mstoykov]

Yeah ... I don't think breaking this is good idea. So I guess at least making less strange in the thresholds is better

[na--]

Ok, closing this and the PR then.