rewrite docker stuff

[xinity]

as gitea grows, we have to rewrite docker stuff in the docker dir.

this issue will stays open until PR is merged and will serve a repo for comments.

feel free to add what you think should be done regarding docker build

[xinity]

keep s6 as an init replacement.

[xinity]

rewrite env variables

[xinity]

dockerfile cleanup

[DblK]

I would suggest to have the smaller image as possible and by doing so, the compilation should be done outside and the binary pushed to the docker (maybe from scratch instead alpine).

I could provide later a link to a docker images that can be used to build Go program and make docker images without compiler program.

Edit 11/10/16:
Here is the link to build dockerfile for Go program with image "SCRATCH"

[xinity]

@DblK feel free to update your comment with the appropriate link :)

[tboerger]

We will use drone to build the binary outside of the docker image, the drone pipeline is in preparation ;)

[xinity]

@tboerger nice !

then @DblK send the link to me :) i'd be happy to learn moaaarrrr go :)

[willemvd]

why do we need that s6 stuff instead of setting things up in the dockerfile?

[tboerger]

@willemvd we need s6 as process manager because we will run more than a single service within the container, at least we need Gitea and openSSH.

I would strongly recommend against using scratch as that renders any form of shell scripting invalid.

[ptman]

The way you say it makes it sound like avoiding shell scripts is a bad thing