Ability to collect Kubernetes cluster metrics

 User story:

 As a user, I want to monitor my Kubernetes cluster to be able to see the current status of my cluster.

UI/UX: designer

Acceptance criteria  

• User able to register K8s cluster into PMM  using UI / API
• User able to see metrics about NODES in K8s cluster  (Autodiscovery? )
• User able to see Container metrics (Autodiscovery? )

Out of scope: 

• K8s Dashboards  
• Containers and Services are presented on the same dashboards  as bare-metal services and nodes so the user able to see DB  metrics together with Node/container metrics 
• Adding standard label  for K8s
• CLI for DBaaS

Suggested implementation: 

 Run Victoriametrics operator

1. Setup crds and operator
   1. https://github.com/VictoriaMetrics/operator/blob/master/docs/quick-start.MD#installing-by-manifest
2. Setup vmagent RBAC
   1. Download and apply https://github.com/VictoriaMetrics/operator/blob/master/config/examples/vmagent_rbac.yaml
3. Run VMAgent
   1. Download https://github.com/VictoriaMetrics/operator/blob/master/config/examples/vmagent.yaml

1. 1. Replace `remoteWrite` field with a path to our VM Service
   2. Apply
2. Apply vmnodescrape to collect node metrics
   1. Download  and apply https://github.com/VictoriaMetrics/operator/blob/master/config/examples/vmnodescrape.yaml
3. Run vmpodscrape to collect pod metrics
   1. Download  and apply https://github.com/VictoriaMetrics/operator/blob/master/config/examples/vmpodscrape.yaml 
4. Install one of those dashboards
   1. https://grafana.com/grafana/dashboards/10566
   2. https://grafana.com/grafana/dashboards/315

How to test: 

1. Setup public address in settings
2. register K8s cluster 
3. check advanced data exploration dashboard for cadvisor related new metrics.

Details:

Questions:

1. How we will add kubernetes cluster to monitoring?
2. Is it ok to request PMM public server address to be able to setup monitoring?