Multiarch builds

[modem7]

Heya,

I've just been doing some work with multi-arch builds on Docker using DroneCI, and decided to try building Greyhole to see if it'd work, so it'd work on things like a Pi or latest ARM based Mac.

Unsure if a multi-arch auto-build system would be useful, I'd be happy to discuss further if it's useful for you.

https://hub.docker.com/repository/docker/modem7/samba-greyhole
https://drone.modem7.com/modem7/samba-greyhole-docker/10

Can happily discuss further either here or elsewhere (so not to clog up issues w/ off-topic chatter) if it's useful!

[gboudreau]

Hi,

I was already creating the x86_64 docker image with my build script (i.e. at the same time I was creating RPM/DEB packages, and uploading a new release on Github), so I just changed that script to create multi-arch images.

Also, Docker Hub disabled auto-builds a few months ago, for free users, so the develop tags on Docker stopped being up to date then. I disabled that integration on Github, and replaced it with a webhook that simply pokes my server when a new push is made, and that now triggers a new Docker multi-arch build that will be tagged develop, and pushed to Docker Hub.

The only thing that is still missing there is that the install_greyhole_vfs.sh script, used in the Dockerfile, is NOT aware of the Docker image platform, and thus is trying to use the pre-compiled VFS module for x86_64 on arm platforms.
I made a change to fix that, but now that it is trying to build the VFS in arm images, the compilation fails. I'm investigating that, and will commit the fix when I find something, and will also publish the pre-compiled VFS modules for arm on my server, to speed up future Docker builds.

Cheers.
(And thanks for the idea for multi-arch build.)

[modem7]

Another note I found (from Hadolint) is:

Dockerfile:3 DL3018 style: Pin versions in apk add. Instead of apk add <package> use apk add <package>=<version>

Dockerfile:11 SC2006 style: Use $(...) notation instead of legacy backticked ....

Dockerfile:15 DL3020 style: Use COPY instead of ADD for files and folders

Dockerfile:16 DL3003 style: Use WORKDIR to switch to a directory

Doesn't change how it works obviously, but more something to keep in mind if it bugs you.

[gboudreau]

Thanks for those.
L3: Since I use a fixed alpine version in FROM (L1), packages don't change (enough) for that to matter.
L11: Yes, indeed. I also prefer $().
L15: I need to use ADD, since COPY doesn't support URLs.
L16: I don't want to change the WORKDIR permanently; I do that on L65. I would need to split my RUN instruction in two, to be able to use WORKDIR here, since the folder in question doesn't exist before it is downloaded and extracted by the few first lines on RUN.