Configure high availability for Dynatrace Operator webhook

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Configure high availability

Dynatrace Operator version 1.9.0+

You can customize the replicas, topologySpreadConstraints, and podDisruptionBudget values independently:

The examples below use Helm values. If you deploy using manifests, you can achieve the same by adjusting the corresponding sections in your deployment manifest directly.

webhook:
  # highAvailability: true # Deprecated, use the following values instead
  replicas: 2
  topologySpreadConstraints:
    - maxSkew: 1
      topologyKey: "topology.kubernetes.io/zone"
      whenUnsatisfiable: ScheduleAnyway
      labelSelector:
        matchLabels:
          internal.dynatrace.com/app: webhook
          internal.dynatrace.com/component: webhook
    - maxSkew: 1
      topologyKey: "kubernetes.io/hostname"
      whenUnsatisfiable: ScheduleAnyway
      nodeTaintsPolicy: Honor
      labelSelector:
        matchLabels:
          internal.dynatrace.com/app: webhook
          internal.dynatrace.com/component: webhook
  podDisruptionBudget:
    minAvailable: 1
    selector:
      matchLabels:
        internal.dynatrace.com/app: webhook
        internal.dynatrace.com/component: webhook

You must keep highAvailability set to true (the default value) for the replicas, topologySpreadConstraints, and podDisruptionBudget values to take effect. If you set highAvailability to false, these fields are ignored. This ensures backward compatibility for users who previously disabled the high availability mode.

Changes to topology spread constraints

The default topologySpreadConstraints is now whenUnsatisfiable: ScheduleAnyway instead of the previous whenUnsatisfiable: DoNotSchedule. This change makes scheduling less aggressive, so the webhook pods can still be scheduled in environments where only a few nodes (one or two) are available. Previously, DoNotSchedule could prevent pods from being scheduled if the topology constraints couldn't be fully satisfied.

Legacy highAvailability Helm value (deprecated)

Dynatrace Operator version 0.6.0+

Starting with Operator version 1.9.0, the highAvailability value is deprecated in favor of the replicas, topologySpreadConstraints, and podDisruptionBudget values. See Configure high availability for the recommended approach.

The legacy highAvailability Helm value offered the following capabilities:

  • Increases replicas to two replicas for webhook deployment.
  • Adds pod topology spread constraints:
    • Pods are spread across different nodes, with the nodes in different zones where possible.
    • Multiple pods are allowed in the same zone.
  • Adds pod disruption budget:
    • It restricts graceful shutdowns of the webhook pod if it's the last remaining pod.