vault agent export container port for scape metrics through podmonitor

[Danny5487401]

Is your feature request related to a problem? Please describe.

there is some need to get metrics like vault.agent.auth.failure from vault agent sidecar

Describe the solution you'd like

expose a port for podmonitor to scrape metrics

Describe alternatives you've considered

add container ports in k8s yaml

Additional context
Add any other context or screenshots about the feature request here.

[LS80]

A PodMonitor requires a port to be defined as a containerPort. You can add that with the existing annotations

vault.hashicorp.com/agent-telemetry-prometheus_retention_time: 2m
vault.hashicorp.com/agent-json-patch: '[{"op": "replace", "path": "/ports", "value": [{"containerPort": 8200, "name": "metrics"}]}]'

apiVersion: monitoring.coreos.com/v1
kind: PodMonitor
metadata:
  name: my-app
spec:
  jobLabel: app
  selector:
    matchLabels:
      app: my-app
  podMetricsEndpoints:
    - port: metrics
      params:
        format:
          - prometheus
      interval: 1m
      filterRunning: true

But Prometheus won't be able to connect as the Vault agent only listens on localhost. You could use a proxy sidecar as mentioned in #331 (comment).

Ideally we would have a single annotation to add all the required configuration.