✨ Metrics for vn-agent

[srirammageswaran8]

User Story

As an operator I would like to export metrics for vn-agent.

Detailed Description

vn-agent does not export metrics at this point. A metrics server is to be enabled by default on the address :9100 and allowed to be configured by the cli option --metrics-addr options. The metrics server can be disabled by cli option --enable-metrics to false. The metrics are default enabled.

vn-agent should expose the below metrics

• Instrumented API calls to super api / Kubelet.
• Count requests with respect to host, tenantName, tenantNamespace, action and responseCode.

/kind feature

[christopherhein]

/retitle ✨ Metrics for vn-agent

[christopherhein]

/assign @srirammageswaran8

[christopherhein]

Thanks @srirammageswaran8, this makes sense to me it will be good to be able to understand the health of each vn-agent and the how they are performing.

cc @Fei-Guo & @charleszheng44 concerns or thoughts?

[Fei-Guo]

Since the vn-agent simply proxies the kublet APIs, I don't see strong need of having pprof enabled. It does make sense to add tenant related metrics in vn-agent.

[srirammageswaran8]

Updated Description and @Fei-Guo agree with you on pprof.

[atosatto]

The metrics server can be disabled by cli option --enable-metrics to false. The metrics are default enabled.

I don't think this is necessary. Perhaps users that don't want to collect metrics can just bind localhost.

[christopherhein]

Issue with this is a traditional deployment the vnagent is run using host networking as a daemonset. So binding to localhost would still make that accessible to clustered workloads.

[atosatto]

Issue with this is a traditional deployment the vnagent is run using host networking as a daemonset. So binding to localhost would still make that accessible to clustered workloads.

LGTM then, thanks for clarifying this!