[FEATURE] Allow setting hostAliases in opensearch cluster and opensearch dashboards

[sebmerkt]

Is your feature request related to a problem?

We are using opensearch with dex as an identity service behind a reverse proxy, which requires us to set a hostAlias in the opensearch pods.

What solution would you like?

The host alias can be defined in the values file and is set in the opensearch cluster and opensearch dashboards pods.

hostAliases:
 - ip: <ip-address>
   hostnames:
   - <hostname>

What alternatives have you considered?

Adding a host alias directly to the /etc/hosts file can not be done in a straight forward way, since that file is mounted in read-only mode within the container. Therefore, using the hostAliases would be the cleanest solution.

Do you have any additional context?

https://kubernetes.io/docs/tasks/network/customize-hosts-file-for-pods/

[andrross]

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