vpa-updater: Initialize counters with 0

[ialidzhikov]

Which component are you using?:
/area vertical-pod-autoscaler

What version of the component are you using?:

Component version: v1.5.0

What k8s version are you using (kubectl version)?:

kubectl version Output

$ kubectl version

What environment is this in?:

Local setup

What did you expect to happen?:

vpa-updater emits per-VPA metrics such as vpa_updater_in_place_updated_pods_total. In particular, vpa_updater_in_place_updated_pods_total is counter.

ChatGPT when asked whether components should always report counts from start, even if 0:

TL;DR Best Practice
✅ Components should always expose counters from start, even if 0.
✅ This ensures dashboards, alerts, and increase()/rate() behave correctly.
❌ Avoid only reporting when the counter increments.

What happened instead?:

vpa-updater does not expose vpa_updater_in_place_updated_pods_total from start with value 0 for VPAs.
This breaks increase()/rate() usages on this counter.

How to reproduce it (as minimally and precisely as possible):

1. Create a new VPA.

2. Ensure that vpa-updater does not emit metrics for vpa_updater_in_place_updated_pods_total for the new VPA until there is an in-place eviction for that VPA:

   % curl http://localhost:8943/metrics | grep resource-consumer
   (no output)
   

3. Adapt the VPA so that it performs an in-place update (for example increase the minAllowed values)

4. Ensure that vpa-updater starts emitting vpa_updater_in_place_updated_pods_total for that VPA only when there is an in-place eviction about it.

   % curl http://localhost:8943/metrics | grep resource-consumer
   vpa_updater_in_place_updated_pods_total{vpa_name="resource-consumer",vpa_namespace="default",vpa_size_log2="0"} 1
   

Anything else we need to know?:
N/A