Describe the feature:
Please, make some of the default hard-coded volumes and volumeMounts optional for Filebeat DaemonSet.

At this moment Filebeat DaemonSet has some hard-coded volumes/volumeMounts:

volumes:
  - name: varlibdockercontainers
    hostPath:
      path: /var/lib/docker/containers
  - name: varlog
    hostPath:
      path: /var/log
  - name: varrundockersock
    hostPath:
      path: /var/run/docker.sock

volumeMounts:
  - name: varlibdockercontainers
    mountPath: /var/lib/docker/containers
    readOnly: true
  - name: varlog
    mountPath: /var/log
    readOnly: true
  # Necessary when using autodiscovery; avoid mounting it otherwise
  # See: https://www.elastic.co/guide/en/beats/filebeat/7.17/configuration-autodiscover.html
  - name: varrundockersock
    mountPath: /var/run/docker.sock
    readOnly: true

It would be great to be able to use them optionally.

For example, to configure them inside extraVolumes and extraVolumeMounts in values.yaml (in the same way like it would be done with Filebeat Deployment);

or alternatively, to have the ability to disable them with using some keys in values.yaml config (example: mountDockerSock: true|false, mountVarLog: true|false)

Describe a specific use case for the feature:

1. If the Docker is not installed on the target machine (for example, if containerd is used):
   then 2 new empty directories would be created:

   • /var/lib/docker/containers/
   • /var/run/docker.sock/

2. The sharing of full /var/log directory is not always desired
   If Filebeat DaemonSet is used only for containers logs delivery, it is excessive to share the whole directory which contains all node logs.
   In case the container is compromised, access to all node logs might also be undesired and could be considered as a security flaw.

3. mounting /var/run/docker.sock is only necessary for autodiscovery as it is written in manifest itself:

# Necessary when using autodiscovery; avoid mounting it otherwise
# See: https://www.elastic.co/guide/en/beats/filebeat/7.17/configuration-autodiscover.html