Security Context

In Kubernetes, a securityContext defines privilege and access control settings for a Pod or Container. You can set up it through the podTemplate section of an Elastic resource specification.

Run as non-root Elasticsearch

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By default, the Elastisearch container is run as root and its entrypoint is responsible to run the Elasticsearch process with the elasticsearch user (defined with ID 1000). In the background, ECK makes sure via an initContainer that the data volume is writable for the elasticsearch user.

To run the Elastisearch container as a non-root user, you need to configure the Elasticsearch manifest with an appropriate security context to make the data volume writable to the elasticsearch user by specifying the right group ID through the fsGroup.

Kubernetes recursively changes ownership and permissions for the contents of each volume to match the fsGroup specified in a Pod’s securityContext when that volume is mounted and makes all processes of the containers part of the supplementary group ID.

For example, if you force the Pod to run as user 1234, you need to set fsGroup accordingly to 1234:

apiVersion: elasticsearch.k8s.elastic.co/v1
kind: Elasticsearch
metadata:
  name: quickstart
spec:
  version: 8.16.0
spec:
  nodeSets:
  - name: default
    count: 3
    podTemplate:
      spec:
        securityContext:
          runAsUser: 1234 
          fsGroup: 1234

	Any containers in the Pod run all processes with user ID `1234`.
	All processes are also part of the supplementary group ID `1234`, that owns the Pod volumes.

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