Elastic Search Kubernetes - Disable memory swapping - elasticsearch

Question

I am using Elastic Search(v7.6.1) on a Kubernetes(v1.19) cluster.
The docs suggests to disable swapping:
https://www.elastic.co/guide/en/elasticsearch/reference/current/setup-configuration-memory.html
My yaml:
apiVersion: elasticsearch.k8s.elastic.co/v1
kind: Elasticsearch
metadata:
name: elastic-cluster-1
spec:
version: 7.6.1
image: docker.elastic.co/elasticsearch/elasticsearch:7.6.1
nodeSets:
- name: default
count: 3
config:
node.master: true
node.data: true
node.ingest: true
podTemplate:
metadata:
labels:
# additional labels for pods
type: elastic-master-node
spec:
nodeSelector:
node-pool: <NODE_POOL>
initContainers:
# Increase linux map count to allow elastic to store large memory maps
- name: sysctl
securityContext:
privileged: true
command: ['sh', '-c', 'sysctl -w vm.max_map_count=262144']
containers:
- name: elasticsearch
# specify resource limits and requests
resources:
limits:
memory: 11.2Gi
requests:
cpu: 3200m
env:
- name: ES_JAVA_OPTS
value: "-Xms6g -Xmx6g"
# Request persistent data storage for pods
volumeClaimTemplates:
- metadata:
name: elasticsearch-data
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 50Gi
storageClassName: ssd
- name: data
count: 2
config:
node.master: false
node.data: true
node.ingest: true
podTemplate:
metadata:
labels:
# additional labels for pods
type: elastic-data-node
spec:
nodeSelector:
node-pool: <NODE_POOL>
initContainers:
# Increase linux map count to allow elastic to store large memory maps
- name: sysctl
securityContext:
privileged: true
command: ['sh', '-c', 'sysctl -w vm.max_map_count=262144']
containers:
- name: elasticsearch
# specify resource limits and requests
resources:
limits:
memory: 11.2Gi
requests:
cpu: 3200m
env:
- name: ES_JAVA_OPTS
value: "-Xms6g -Xmx6g"
# Request persistent data storage for pods
volumeClaimTemplates:
- metadata:
name: elasticsearch-data
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 50Gi
storageClassName: ssd
# Google cloud storage credentials
secureSettings:
- secretName: "gcs-credentials"
http:
service:
spec:
# expose this cluster Service with a LoadBalancer
type: LoadBalancer
tls:
certificate:
secretName: elasticsearch-certificate
It's not clear to me how to change this yaml in order to disable swapping correctly. Changing each manually is not an option because in every restart the configuration will be lost.
How can I do this?

Answer 1

First of all k8s cluster by default will have swap disabled, this is actually a mandatory requirement. For most cases; especially cloud managed cluster which follows the requirement, you do not need to worry about swapping issue. Even for 1.22, enabling swap is only an alpha feature.
If for whatever reason you need to deal with this, you can consider setting bootstrap.memory_lock to true.
...
containers:
- name: elasticsearch
env:
- name: bootstrap.memory_lock
value: "true"
...

Answer 2

Up until recently, Kubernetes had no control over swapping.
As of 1.22, there's a new alpha feature to do this. The CRI spec does allow for swap allocations. I didn't find anything new in that regard, in the Pod specification: as far as I understand, currently, you could either allow your containers to use as much swap as they can (UnlimitedSwap), or limit swap+memory usage to whatever memory limit you set on your container (LimitedSwap).
Since you're running 1.19, this shouldn't concern you right now. A good practice while deploying your cluster would have been to make sure there is no swap at all on your nodes, or set swapiness to 0 or 1. Checking Kubespray playbooks, we can see they would still unconditionally disable swap.
You can connect your nodes (ssh), make sure there's no swap -- or disable it otherwise. There's nothing you can do in that ElasticSearch object directly.