Docker-alpine: Please confirm source of rootfs

[Wilfred]

The rootfs.tar.xz has the following checksum:

$ sha256sum rootfs.tar.xz
29671a7b23525fa08d67a8ce63417cce5e6b8025da1c581e59ab237d2f920e9f  rootfs.tar.xz
$ unxz rootfs.tar.xz
$ sha256sum rootfs.tar
28ad6d95e3c021e479cee0683951cf1cd3d5395ac7ac8e034665c3dede6bd009  rootfs.tar

whereas the upstream alpine root filesystem differs:

$ wget http://dl-cdn.alpinelinux.org/alpine/v3.7/releases/x86_64/alpine-minirootfs-3.7.0-x86_64.tar.gz
$ sha256sum alpine-minirootfs-3.7.0-x86_64.tar.gz # this matches the .sha256 provide by alpine
17e8275545aca7a6eaf4e43759a091d33bd9eb9cf11805118773dc940c8b94ac  alpine-minirootfs-3.7.0-x86_64.tar.gz
$ gunzip alpine-minirootfs-3.7.0-x86_64.tar.gz
$ sha256sum alpine-minirootfs-3.7.0-x86_64.tar
7bf94991024e6ad6d2784f29b52d93b6eedd2d18ea0093fd72d5f32b20765e27  alpine-minirootfs-3.7.0-x86_64.tar

What has generated this rootfs file? Can I replicate it?

[andyshinn]

The rootfs for x86_64 images are built using our own builder (https://github.com/gliderlabs/docker-alpine/tree/master/builder). At the time we started building images there were no upstream minirootfs images. But these days we could think about basing everything off of upstream minirootfs.

[Wilfred]

Thanks :)