armv8 support

[raheem-imcapsule]

Unable to use in armv8 systems like Apple m1 chip.
This image will have more scope if supported for different platform variant

[markhobson]

Hi, I've not had to use Docker architectures yet so I'm interested in how the build process would work. Presumably each Docker tag would need to be built for multiple architectures, so it's a question of how best to manage this.

I see the official docs for architectures other than amd64. I'm open to suggestions.

[markhobson]

Docker blog and docs on multi-arch builds. Will have to give it a go sometime.