Build the right LinuxKit version

[gianarb]

Probably there is a better way but this one works. Now Nix installs the
right version of LinuxKit (v0.8 the one it installed originally does not
support build -docker flag)

[deitch]

Actually, v0.8 doesn't need --docker flag, because it only uses docker. That later commit uses direct communication with a registry, a local cache, and expanding images directly. --docker is for if you are building a package locally and want to use that image instead of something from the registry (because yours is more up to date, or you don't have the image in the registry).

[gianarb]

@deitch with the current version v0.8 the --docker flag is not available yet. I need that flag as you said because we rely on locally built images. Does it make sense?

[deitch]

Sorry, I wasn't making it very clear.

• Prior to commit ec80e6cf07e8fd1d1744ebb29afe72d05fa65575, it always used the local docker cache. Every image that it pulled from a registry to build a linuxkit image was via docker pull, every lay out of a filesystem was via docker create and then docker export. It always used local docker (hence, you didn't need --docker; that was precisely how it worked). This includes v0.8.
• Beginning with commit ec80e6cf07e8fd1d1744ebb29afe72d05fa65575, it doesn't use docker at all, pulling everything from registry to a local cache, no need for a docker daemon. But if you want to use locally built images, then you need --docker.

If you are using v0.8 (pre-ec80e6cf07e8fd1d1744ebb29afe72d05fa65575), then you don't need the --docker flag, as that is how it operates.

[gianarb]

I see, well we are building from the master branch 👍 in this way we are already up to speed I suppose but now I know what's happening! Thanks