fix(ingress-controller): render valid leader-election keys and align config defaults

[kayx23]

Problem

The apisix-ingress-controller Helm chart 1.2.x renders three leader-election settings with camelCase names:

leader_election:
  leaseDuration: 15s
  renewDeadline: 10s
  retryPeriod: 2s

APISIX Ingress Controller 2.1.0 accepts the YAML keys lease_duration, renew_deadline, and retry_period. Its configuration loader uses non-strict yaml.Unmarshal, so the rendered camelCase keys are silently ignored.

As a result:

• The chart's default 15s lease duration is not applied; the binary default 30s remains effective.
• The chart's default 10s renewal deadline is not applied; the binary default 20s remains effective.
• User overrides of .Values.config.leaderElection.leaseDuration, renewDeadline, and retryPeriod do not affect controller behavior.

Reproduction

Render the default ConfigMap:

helm template test apisix/apisix-ingress-controller \
  --show-only templates/configmap.yaml

The rendered config.yaml contains camelCase leader-election keys. Starting controller 2.1.0 with that configuration leaves the prefilled NewLeaderElection() defaults unchanged because those keys do not match the binary's explicit YAML tags.

Related default drift

The same chart surface contains additional defaults that should be reconciled with the controller or explicitly documented as intentional:

Field	Controller 2.1.0	Chart values.yaml	Template fallback
leader_election_id	apisix-ingress-gateway-leader	apisix-ingress-controller-leader	apisix-ingress-controller-leader
provider.sync_period	1h	1m	1s
server_addr	:9092	Not exposed	Not rendered
enable_server	false	Not exposed	Not rendered

The template fallback for sync_period is a hidden third value that is used when the Helm value is absent or empty.

The cross-product API7/APISIX comparison and default-alignment decisions are tracked in api7/api7-ingress-controller#462. This issue is limited to the upstream APISIX chart and controller contract.

Expected behavior

• The chart should render configuration keys accepted by the controller.
• Every documented Helm override should change the effective controller configuration.
• values.yaml, template fallbacks, and controller defaults should agree unless a chart-specific override is intentional and documented.

Proposed acceptance criteria

• Render leader-election keys as lease_duration, renew_deadline, and retry_period.
• Verify that setting each config.leaderElection.* value changes the loaded controller configuration.
• Reconcile the provider.syncPeriod value and template fallback with the controller default, or document why the Helm-installed behavior intentionally differs.
• Decide whether the chart should preserve its leader_election_id override; include upgrade guidance if it changes.
• Decide whether enableServer and serverAddr should be exposed consistently.
• Add a test that renders the chart and loads the resulting config.yaml through the controller parser so unknown or ineffective keys are detected.

Evidence

• Controller YAML tags
• Controller defaults
• Controller configuration loader
• Chart values
• Chart ConfigMap template

[kayx23]

The recent listenerPortMatchMode default drift is now tracked separately so this issue can remain focused on leader-election keys and the broader configuration contract:

• Focused issue: fix(ingress-controller): align listenerPortMatchMode chart default with controller #1001
• Fix PR: fix(ingress-controller): align listener port matching default #1002

The PR changes the controller chart default and template fallback to off, adds upgrade guidance and render regression coverage, and bumps the chart to 1.3.1.