A PodDisruptionBudget Kubernetes Resource

PodDisruptionBudget (PDB) is a Kubernetes resource that allows you to achieve high availability of scalable application services when the cluster administrators perform voluntary disruptions to manage the cluster nodes.

PDB restricts the number of pods that are down simultaneously from voluntary disruptions. Defining PDB is helpful to keep the services running undisrupted when a pod is deleted accidentally or deliberately. PDB can be defined for high available and scalable NRF services. For more information on the services that are supported, see Table A-1.

It allows safe eviction of pods when a Kubernetes node is drained to perform maintenance on the node. It uses the maxPdbUnavailable parameter specified in the Helm chart to determine the maximum number of pods that can be unavailable during a voluntary disruption.

Note:

The maxPdbUnavailable parameter has a predefined value.

For example, when a maxPdbUnavailable is 25%, pod evictions are allowed as long as no more than 25% of the desired pods are in unhealthy state.

For more information about this functionality, see https://kubernetes.io/docs/concepts/workloads/pods/disruptions/#pod-disruption-budgets.

Note:

The performance and capacity of the NRF system may vary based on the call model, Feature or Interface configuration, and underlying CNE and hardware environment.

Table A-1 Predefined PodDisruptionBudget Value

Microservice	PDB Value (maxPdbUnavailable)
<helm-release-name>-nfregistration	25%
<helm-release-name>-nfsubscription	25%
<helm-release-name>-nfdiscovery	25%
<helm-release-name>-nrfauditor	25%
<helm-release-name>-nrfconfiguration	Not Applicable Note: PDB not supported for this microservice.
<helm-release-name>-appinfo	50%
<helm-release-name>-nfaccesstoken	25%
<helm-release-name>-nrfartisan	Not Applicable Note: PDB not supported for this microservice.
<helm-release-name>-alternate_route	25%
<helm-release-name>-egressgateway	25%
<helm-release-name>-ingressgateway	25%
<helm-release-name>-performance	50%

Note:

<helm-release-name> is the Helm release name. For example, if helm-release-name is "ocnrf", then nfsubscription microservice name will be "ocnrf-nfsubscription".