Group permission inconsistency between Kibana and Elasticsearch docker images

I noticed the latest Kibana and Elasticsearch docker images (7.10.0) have a difference that caused me issues when trying to change ownership of my bind mounted configuration and logging directories. The Elasticsearch documentation (https://www.elastic.co/guide/en/elasticsearch/reference/current/docker.html) states that you can change the ownership of data and log directories as long as the group owner is 0 and the group permissions are rwx. So I incorrectly assumed that would also apply to Kibana but then my Kibana containers would not work.

Upon further investigation I found that in the /etc/group file on the Elasticsearch container there is a group with GID 1000 for the elasticsearch group but the elasticsearch user is also appended to the end of the line for the root group with GID 0. The Kibana container is missing the part where the kibana group is appended to GID 0.

It would be helpful if these were consistent. I haven't looked at the beats containers yet to see which way they go.

Hi @Aaron_Norton,

Thanks for reporting this.
I'm working on a PR to make sure we fix that inconsistency https://github.com/elastic/kibana/pull/88606!

Cheers
Tiago