Use maxUnavailable for PodDisruptionBudgets

[MarceloRGonc]

Part of OPS-4725

[linear]

OPS-4725

[Copilot]

Pull request overview

Updates the Helm chart’s PodDisruptionBudget (PDB) configuration to default to maxUnavailable: 1 (replica-count safe for replicas: 1) while still supporting minAvailable overrides, and aligns documentation/examples with the chart’s real values schema.

Changes:

• Switch component PDB defaults from minAvailable to maxUnavailable: 1 in chart/values.yaml.
• Update all five PDB templates to render maxUnavailable when set, otherwise fall back to minAvailable.
• Fix docs/examples (README + EKS guide + AGENTS) to use *.podDisruptionBudget schema and document the maxUnavailable preference.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
README.md	Updates PDB configuration example and adds guidance on maxUnavailable vs minAvailable.
docs/DEPLOY_TO_AWS_EKS.md	Updates the EKS deployment values example to the correct PDB schema/defaults.
chart/values.yaml	Changes default PDB value keys to maxUnavailable: 1 for all components.
chart/templates/pdb-app.yaml	Renders maxUnavailable when set, else falls back to minAvailable.
chart/templates/pdb-engine.yaml	Renders maxUnavailable when set, else falls back to minAvailable.
chart/templates/pdb-nginx.yaml	Renders maxUnavailable when set, else falls back to minAvailable.
chart/templates/pdb-analytics.yaml	Renders maxUnavailable when set, else falls back to minAvailable.
chart/templates/pdb-tables.yaml	Renders maxUnavailable when set, else falls back to minAvailable.
AGENTS.md	Updates internal guidance to reflect the maxUnavailable: 1 default and drain-safety rationale.

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[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated no new comments.

Suppressed comments (6)

chart/values.yaml:196

• Setting maxUnavailable: 1 in the chart defaults means any existing user overrides that only set podDisruptionBudget.minAvailable will now be ignored, because the PDB templates render maxUnavailable whenever it’s non-nil (e.g. chart/templates/pdb-app.yaml:12-16). If backward-compatibility for existing minAvailable overrides is required, consider leaving maxUnavailable unset/null in values.yaml and defaulting to maxUnavailable: 1 in the templates only when both maxUnavailable and minAvailable are unset.

  # Pod Disruption Budget - ENABLED BY DEFAULT
  podDisruptionBudget:
    enabled: true
    maxUnavailable: 1

chart/templates/pdb-app.yaml:15

• default 1 treats an explicit minAvailable: 0 as “empty” and will render 1 instead of 0. If someone intentionally wants minAvailable: 0 (valid for PDBs), this template can’t express it. Default only when the value is actually nil/unset.

  minAvailable: {{ .Values.app.podDisruptionBudget.minAvailable | default 1 }}

chart/templates/pdb-engine.yaml:15

• default 1 treats an explicit minAvailable: 0 as “empty” and will render 1 instead of 0. If someone intentionally wants minAvailable: 0 (valid for PDBs), this template can’t express it. Default only when the value is actually nil/unset.

  minAvailable: {{ .Values.engine.podDisruptionBudget.minAvailable | default 1 }}

chart/templates/pdb-nginx.yaml:15

• default 1 treats an explicit minAvailable: 0 as “empty” and will render 1 instead of 0. If someone intentionally wants minAvailable: 0 (valid for PDBs), this template can’t express it. Default only when the value is actually nil/unset.

  minAvailable: {{ .Values.nginx.podDisruptionBudget.minAvailable | default 1 }}

chart/templates/pdb-analytics.yaml:15

• default 1 treats an explicit minAvailable: 0 as “empty” and will render 1 instead of 0. If someone intentionally wants minAvailable: 0 (valid for PDBs), this template can’t express it. Default only when the value is actually nil/unset.

  minAvailable: {{ .Values.analytics.podDisruptionBudget.minAvailable | default 1 }}

chart/templates/pdb-tables.yaml:15

• default 1 treats an explicit minAvailable: 0 as “empty” and will render 1 instead of 0. If someone intentionally wants minAvailable: 0 (valid for PDBs), this template can’t express it. Default only when the value is actually nil/unset.

  minAvailable: {{ .Values.tables.podDisruptionBudget.minAvailable | default 1 }}