Run as limited user (not root)

[amcclain]

While running in a Docker container and using the official nginx image should have us in a reasonable state w.r.t. security, we should follow best practices and not run this container as root.

Note this might involve moving off of nginx image base (not sure - need to research) as well as swapping to an alternate port. The port remapping back to 80 or 443 can then be handled at the k8s / docker layer.

Note complimentary xh-tomcat issue here: xh/xh-tomcat#1

[amcclain]

https://github.com/nginxinc/docker-nginx-unprivileged