feat(kuma-cp): Resource counter based on Mesh insights

[jewertow]

Signed-off-by: Jacek Ewertowski jacek.ewertowski1@gmail.com

Issues resolved

Fix #1165

@jakubdyszkiewicz please check if it is what you expected?

[lobkovilya]

Hey @jewertow! You're on the right track, don't hesitate to move the PR from draft.

There is one moment that concerns me, MeshInsight contains information only about mesh-scoped resources, but the previous implementation of count() took into account all resources. It'd be great to cover the existing behavior of count with some simple test at first and then make sure your code passes it.

[jewertow]

@lobkovilya Yes, you're right that MeshInsight contains information only about mesh-scoped resources, but I looked how the metric "resource_count" is used and I found only two usages:

1. sum by (zone, instance) (resources_count{instance=~\"$instance\",resource_type!~\"Dataplane|DataplaneInsight|Zone|ZoneInsight\"})
2. sum by (zone, instance) (resources_count{instance=~\"$instance\",resource_type=\"Dataplane\"})

Am I right that only mesh and zone are global-scoped resources? If it's true then this implementation should be correct, because this metric is not used to present number of meshes or zones.

I am going to add a unit test and then I will change this draft to pull request.

[lobkovilya]

In addition to zone and mesh there is also config. Anyway, we're going to add new resources both mesh-scoped and global-scoped and it'd great to have them in resources_count without additional changes.

So I'd suggest having this code in a more generic manner: iterate over all types that we have and use method Scope to decide where to take the value from - resManager for global-scope and MeshInsight for mesh-scope.

[jewertow]

I added a test for resource counter. To make it possible I had to refactor existing code. I added new function Start to counter that accepts a ticker to enable injecting test tickers. The most important point is that the counter test relies on resyncer. Creating a resyncer adds a little bit of complexity to setup of this test, but simplifies logic of a test. What do you think?

[lobkovilya]

Overall looks great, thanks for your contribution! Just a small comment

[lobkovilya]

I think we can rename this to StartWithTicker and call it from Start

[jewertow]

Done