minAvailable: 0 in PodDisruptionBudget renders as N/A due to Go template falsy-zero check

[S0meth1ng85]

Setting podDisruptionBudget.minAvailable: 0 (either in defaults or at the component level) results in a PDB with neither minAvailable nor maxUnavailable in the spec. Kubernetes shows N/A / N/A for both fields, and ALLOWED DISRUPTIONS: 0 — effectively blocking all voluntary evictions instead of allowing them.

Root Cause:

In templates/_helpers.tpl, the cloudzero-agent.generatePodDisruptionBudget template uses truthiness checks to conditionally render PDB fields:

{{- if $pdb.minAvailable }}
  minAvailable: {{ $pdb.minAvailable }}
{{- end }}
{{- if $pdb.maxUnavailable }}
  maxUnavailable: {{ $pdb.maxUnavailable }}
{{- end }}

In Go templates, the integer 0 is falsy, so {{- if 0 }} evaluates to false. The minAvailable line is never rendered, even though minAvailable: 0 is a valid Kubernetes PDB value.

Steps to Reproduce:

Set PDB configuration in values override:

defaults:
  podDisruptionBudget:
    enabled: true
    minAvailable: 0

Or at component level:

components:
  aggregator:
    podDisruptionBudget:
      enabled: true
      minAvailable: 0

Deploy the chart.

Check PDBs:

kubectl get pdb -n cloudzero

Expected Result:

NAME                        MIN AVAILABLE   MAX UNAVAILABLE   ALLOWED DISRUPTIONS
cloudzero-cz-aggregator     0               N/A               3

Actual Result:

NAME                        MIN AVAILABLE   MAX UNAVAILABLE   ALLOWED DISRUPTIONS
cloudzero-cz-aggregator     N/A             N/A               0

Note: The bundled kube-state-metrics subchart (from prometheus-community) does not have this issue because its pdb.yaml uses {{ toYaml .Values.podDisruptionBudget | indent 2 }} without individual field conditionals.

Workaround:
Use maxUnavailable: "100%" instead of minAvailable: 0 to achieve the same effect.