minimize docker image

[alexeldeib]

2.5Mi -- rust formatter compiled for release
1.8Mi -- static file binary ==> probably remove, only need for debug
3.4Mi -- static mount binary ==> take from busybox?
3.4Mi -- static umount binary ==> take from busybox?
1.2Mi -- amd64/busybox
17.9Mi -- gcr.io.distroless/static
19.8Mi -- gcr.io.distroless/cc
49.0Mi -- e2fsprogs
71.9Mi -- final image

e2fsprogs seems like the obvious candidate for minimization. We currently copy everything from e2fsprogs into our final image, picking up lots of random (if useful) stuff.

az-local-pvc/Dockerfile

Line 67 in d97fd95

COPY --from=build /app/e2fsprogs/sbin/* /usr/local/bin/

we only need the minimal tooling to create whatever kind of file system we want on the disk. Currently that is mkfs.ext4 // mke2fs -t ex4. it'd be nice to keep some things like wipefs too, but it's not critical.