# istio_disable-track-remaining-cb-metrics.yaml
apiVersion: release-notes/v2
kind: feature
area: traffic-management
releaseNotes:
  - |
    **Added** a new feature flag `DISABLE_TRACK_REMAINING_CB_METRICS` to control circuit breaker remaining metrics tracking.
    When set to `false` (default), circuit breaker remaining metrics will not be tracked, which can improve performance.
    When set to `true`, circuit breaker remaining metrics will be tracked (legacy behavior).
    This feature flag will be removed in a future release.

upgradeNotes:
  - title: Circuit breaker metrics tracking behavior change
    content: |
      The default behavior for circuit breaker remaining metrics tracking has changed. Previously, these metrics
      were tracked by default. Now, tracking is disabled by default for better proxy memory usage.
      
      To maintain the previous behavior where remaining metrics were tracked, you can:
      
      1. Set the environment variable `DISABLE_TRACK_REMAINING_CB_METRICS=false` in your Istiod deployment
      2. Use the compatibility version feature to get the legacy behavior
      
      This change affects the `TrackRemaining` field in Envoy's circuit breaker configuration.