Pod disruption budget

A Pod Disruption Budget (PDB) allows you to limit the disruption to your application when its pods need to be rescheduled for some reason such as upgrades or routine maintenance work on the Kubernetes nodes.

ECK manages a default PDB per Elasticsearch resource. It allows one Elasticsearch Pod to be taken down, as long as the cluster has a green health. Single-node clusters are not considered highly available and can always be disrupted.

In the Elasticsearch specification, you can change the default behaviour as follows:

			apiVersion: elasticsearch.k8s.elastic.co/v1
kind: Elasticsearch
metadata:
  name: quickstart
spec:
  version: 8.16.1
  nodeSets:
  - name: default
    count: 3
  podDisruptionBudget:
    spec:
      minAvailable: 2
      selector:
        matchLabels:
          elasticsearch.k8s.elastic.co/cluster-name: quickstart

Note

maxUnavailable cannot be used with an arbitrary label selector, therefore minAvailable is used in this example.

Pod disruption budget per nodeset ¶

You can specify a PDB per nodeset or node role.

			apiVersion: elasticsearch.k8s.elastic.co/v1
kind: Elasticsearch
metadata:
  name: quickstart
spec:
  podDisruptionBudget: {} 1
  version: 8.16.1
  nodeSets:
    - name: master
      count: 3
      config:
        node.roles: "master"
        node.store.allow_mmap: false
    - name: hot
      count: 2
      config:
        node.roles: ["data_hot", "data_content", "ingest"]
        node.store.allow_mmap: false

apiVersion: policy/v1
kind: PodDisruptionBudget
metadata:
  name: hot-nodes-pdb
spec:
  minAvailable: 1 5
  selector:
    matchLabels:
      elasticsearch.k8s.elastic.co/cluster-name: quickstart 3
      elasticsearch.k8s.elastic.co/statefulset-name: quickstart-es-hot 6
  1. Disable the default Elasticsearch pod disruption budget.
  2. Specify pod disruption budget to have 2 master nodes available.
  3. The pods should be in the "quickstart" cluster.
  4. Pod disruption budget applies on all master nodes.
  5. Specify pod disruption budget to have 1 hot node available.
  6. Pod disruption budget applies on nodes of the same nodeset.