Run commands inside docker container as a non root user

[vblagoje]

Is your feature request related to a problem? Please describe.
We currently run gunicorn as a root user, exposing not only the contents of the docker image to potential attackers but also leaving a backdoor open for an attacker to gain access to the host machine.

Describe the solution you'd like
Run all internet-facing commands as non-root user thus limiting potential security issues for the Haystack deployments.

Describe alternatives you've considered
N/A

For more context and a brief introduction refer to this excellent article