Cross-compile binary for ARMv7 and ARM 64

[yankeexe]

Description

Current binary distribution for pack only supports amd64 . Adding binaries for ARM will enable pack to be used on Raspberry Pi and similar hardware.

Proposed solution

Cross-compile binaries for ARM v7 and ARM 64

Describe alternatives you've considered

Additional context

• This feature should be documented somewhere

[alexellis]

Thank you @jromero 👍 👍

[dfreilich]

@yankeexe @alexellis I was just looking into doing this (and sorry this took so long)! I'm pretty unfamiliar with the arm64/armv7 ecosystem, so two questions:

1. Can we assume that testing with the normal linux github action runner (ubuntu-18.04) will give sufficient coverage for linux systems, or should we test it on those architectures as well? (I'm assuming we should test it, and I've opened Add/host terraform templates for creating ARM 64, ARM v7 and M1 runners ci#23 as a result, but if that's not the case, great!)
2. Is the ask to just publish in our release, or to publish to a package manager?

Again, I don't know the ecosystem at all, so I'm sorry if these are super basic questions!

[dfreilich]

I'm assuming that this is blocked at the moment on buildpacks/lifecycle#435. When we tried running an arm64 compiled pack with an extant builder, we saw:

pack build -B gcr.io/buildpacks/builder:v1 ${IMAGE}
v1: Pulling from buildpacks/builder
Digest: sha256:889d1cc172467dfb5560c69e5a24d8215804e0fb9ae36e2774f33bc2033ffb8c
Status: Image is up to date for gcr.io/buildpacks/builder:v1
v1: Pulling from buildpacks/gcp/run
Digest: sha256:35c7b9995b7b0ad398e504bc178e38b28626e1ce9052cfeabc8750fc313b4d36
Status: Image is up to date for gcr.io/buildpacks/gcp/run:v1
standard_init_linux.go:190: exec user process caused "exec format error"
ERROR: failed to build: executing lifecycle: failed with status code: 1

[briandealwis]

@dfreilich that specific error is related but different from buildpacks/lifecycle#435: gcr.io/buildpacks/builder:v1 is linux/amd64-only. Your build should work if you have binfmt_exec extensions configured, though it will produce a linux/amd64 image, though note that there is an issue involving untrusted builders (#1197).

[jromero]

If I'm not mistaken this issue is now completely resolved provided all referenced issues are resolved. If that is wrong, please feel free to re-open with more detail on what's missing.

[josegonzalez]

Should arm releases for pack be added to each release? I'm not seeing them on the latest release, but maybe this was only implemented for MacOS?

[jromero]

@josegonzalez you are right. I misread the issue as being related to Apple Silicon/M1. Re-opened.

[josegonzalez]

Is this "just"

• adding a new entry to the build matrix: https://github.com/buildpacks/pack/blob/main/.github/workflows/build.yml#L137
• add a stanza like this for linux-arm: https://github.com/buildpacks/pack/blob/main/.github/workflows/build.yml#L191

Or is there something I'm missing?

[willianpaixao]

@josegonzalez I took the freedom and went ahead to test your assumption. #1401