feat(kuma-cp) mesh insight

[lobkovilya]

Summary

Current PR adds MeshInsight entity that allows tracking number of mesh scoped resources.

API

• GET: /mesh-insights

{
 "total": 2,
 "items": [
  {
   "type": "MeshInsight",
   "name": "default",
   "creationTime": "2020-11-11T07:07:41Z",
   "modificationTime": "2020-11-11T07:07:41Z",
   "lastSync": "2020-11-11T07:16:52.651679130Z",
   "dataplanes": {
    "total": 4,
    "online": 4
   },
   "policies": {
    "Config": {
     "total": 4
    },
    "TrafficPermission": {
     "total": 2
    }
   }
  },
  {
   "type": "MeshInsight",
   "name": "mymesh1",
   "creationTime": "2020-11-11T07:13:04Z",
   "modificationTime": "2020-11-11T07:13:04Z",
   "lastSync": "2020-11-11T07:16:52.662834520Z",
   "dataplanes": {},
   "policies": {
    "Config": {
     "total": 4
    },
    "Secret": {
     "total": 2
    },
    "TrafficPermission": {
     "total": 1
    }
   }
  }
 ],
 "next": null
}

• GET /mesh-insights/default

{
 "type": "MeshInsight",
 "name": "default",
 "creationTime": "2020-11-11T07:07:41Z",
 "modificationTime": "2020-11-11T07:07:41Z",
 "lastSync": "2020-11-11T07:18:27.657468810Z",
 "dataplanes": {
  "total": 4,
  "online": 4
 },
 "policies": {
  "Config": {
   "total": 4
  },
  "TrafficPermission": {
   "total": 2
  }
 }
}

New command for kumactl:

$ kumactl inspect meshes
MESH      DATAPLANES   TRAFFIC PERMISSIONS   TRAFFIC ROUTES   CIRCUIT BREAKERS   HEALTH CHECKS   FAULT INJECTIONS   EXTERNAL SERVICES   TRAFFIC TRACES   TRAFFIC LOGS   PROXY TEMPLATES
default   4/4          2                     0                0                  0               0                  0                   0                0              0
mymesh1   0/0          1                     0                0                  0               0                  0                   0                0              0

Full changelog

• New event-based approach. We don't recalculate MeshInsight often. We do that when an event happens, but not more often than minResyncTimeout(using rateLimiter) and every maxResyncTimeout to keep it synced in case of failures.

Issues resolved

Fix #XXX

Documentation

• Link to the website documentation PR

[subnetmarco]

In the API this is /mesh-insights, but the other insights I believe are /dataplane+insights. Shouldn't we have some consistency here?

[jakubdyszkiewicz]

nice, I like the event-based approach, I think it has a lot of potential in the future.