`uname` config option unusable

[Krzmbrzl]

Due to the removal of a dedicated, named user account in #50, the uname server config option is no longer usable. This is because that option requires a non-root user with a known name to exist.

The fix should be as simple as adding back a USER directive into the Dockerfile (optionally with some runtime variables that can be used to set that user's UID and GID).

[Gunzinger]

Good morning, can the code here be added back?
https://github.com/mumble-voip/mumble-docker/pull/50/files#diff-dd2c0eb6ea5cfc6c4bd4eac30934e2d5746747af48fef6da689e85b752f39557L67-L71
(Creation of the user account with specific UID and GID in the Dockerfile)

As far as I read the code from #50 this should fix setups like mine since PUID and PGID are still initialized with 10000, same as previous mumble user inside the container, and all other setups should not be affected by the mumble user existing inside the container with this UID/GID combination.

Removal of this option broke all my deployments which start as root to read letsencrypt certificates (with 600 permissions) and then drop down to the mumble user :/
(They pull tags automatically and regularly, and this broke the v1.5.735 tag when this config is used)

One further thing which I find dangerous is that #50 clones master of https://github.com/ncopa/su-exec without a fixed tag/version hash, which makes this whole mumble-docker image vulnerable to build chain attacks should hostile code be injected into the su-exec repository with a new commit. (Added suggestion how to solve this here: https://github.com/mumble-voip/mumble-docker/pull/50/files#r1918272775 )

[Krzmbrzl]

can the code here be added back?

yes, I think so. Though it would likely be even better if we moved it into the entry point script such that the MUMBLE_UID and MUMBLE_GID values can be set at runtime (they should default to the PUID and PGID values).

[azlux]

That the reason why I've change id mumble uid/gid before the start.
https://github.com/mumble-voip/mumble-docker/pull/43/files#diff-6f9d41d046756f0ddc2fcee0626bdb50100d12b88f293734eff742818e03efa2R168-R171

You should take back this part.

[Gunzinger]

Opened PR #56 .
Would be interested in opinion on defaults.