Use recent multiple FROM

[JanWielemaker]

Should we reorganise the Dockerfile to use the recent multiple FROM lines, which gives us both a small image and layering to speedup building relatively easily? So, we get (if I understand the system correctly).

• Install runtime dependencies
• Install system in multiple layers
• Restart from the image with dependencies, copying /swipl from the install layer

Supported as of Docker 17.06 if I recall correctly. I'd assume that the generated images also work with older docker instances.

[ninjarobot]

Yes, now that docker hub is updated to 17.06, we could switch to multi-stage images, and the resulting image works with older runtimes just fine. I can pick this up unless you already have something in the works.

[JanWielemaker]

I haven't done anything and you know more about Docker! Please go ahead.

If you do not see `why not', I would like to pick up #9. I guess worst case this might mean a little merging, but most of the work is what to clone from where, which prerequisites to install and how to get the add-ons built.

[ninjarobot]

@JanWielemaker - I apologize - Docker Hub is upgraded, but apparently the rest of their infrastructure for official-images doesn't support building multi-stage images. I'm sorry about the trouble, but I would be happy to combine the multi-stage Dockerfile into a single stage.

[JanWielemaker]

No apology needed. It is a pity though. Yes, please turn it into a single stage build. Let us keep the branch. Hope Docker will soon update their official infrastructure as well.

[rrooij]

Isn't it officially supported on Hub's infrastructure as well now?