Add architecture for images created withpack buildpack package

[jericop]

Summary

This changes the behavior of pack buildpack package to include the platform architecture when the docker daemon is available, or from runtime.GOARCH otherwise. It also has support for user-supplied architecture, but this is currently not supported through any pack cli arguments.

Output

Before

The current behavior is described in #2079

After

You can verify the change in this PR by following the steps below.

Note that docker needs to be configured to build multi-arch images for this to work as described here.

Steps

1. Create the following dockerfile in a directory.

FROM golang:1.21 as builder
WORKDIR /pack

RUN git clone --depth 1 --branch add-arch-in-buildpack-package https://github.com/jericop/pack.git /pack
RUN make mod-tidy build

FROM bitnami/git
USER root
WORKDIR /workspace

COPY --from=builder /pack/out/pack /usr/local/bin/pack

RUN <<RUN_EOF

image_arch=amd64
if [ $(arch) = "aarch64" ]; then
  image_arch=arm64
fi

git clone --depth 1 --branch main https://github.com/buildpacks/samples.git

pack buildpack package ttl.sh/jericop-buildpack-add-arch-in-buildpack-package:${image_arch} --publish \
  --path samples/buildpacks/hello-world

RUN_EOF

2. Run the following docker buildx command to create and publish buildpacks to ttl.sh, an ephemeral registry.

docker buildx build --platform linux/amd64,linux/arm64 .

3. Inspect the image config with crane to confirm the architecture is an empty string.

➜  pack-arch-issue crane ls ttl.sh/jericop-buildpack-add-arch-in-buildpack-package
amd64
arm64
➜  pack-arch-issue crane config ttl.sh/jericop-buildpack-add-arch-in-buildpack-package:amd64 | jq .architecture
"amd64"
➜  pack-arch-issue crane config ttl.sh/jericop-buildpack-add-arch-in-buildpack-package:arm64 | jq .architecture
"arm64"
➜  pack-arch-issue 

Documentation

• Should this change be documented?
  • Yes, see #___
  • No

It is generally expected that when you build an image on a certain platform and architecture, the image you produce should be meant to run on that platform and architecture. As a result I don't believe this change needs to be documented.

Related

Resolves #2079
It should also resolve #1968, which was fixed by retry logic.

[codecov]

Codecov Report

Attention: Patch coverage is 83.33333% with 7 lines in your changes are missing coverage. Please review.

Project coverage is 79.70%. Comparing base (2df4445) to head (1900afe).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2080      +/-   ##
==========================================
+ Coverage   78.96%   79.70%   +0.75%     
==========================================
  Files         176      176              
  Lines       13246    13261      +15     
==========================================
+ Hits        10459    10569     +110     
+ Misses       2119     2023      -96     
- Partials      668      669       +1     

Flag	Coverage Δ
os_linux	78.61% <83.34%> (+0.01%)	⬆️
os_macos	76.34% <83.34%> (+0.05%)	⬆️
os_windows	79.10% <83.34%> (+0.79%)	⬆️
unit	79.70% <83.34%> (+0.75%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

[natalieparellano]

This is a bit weird - why is Platform a field on Platform?

[jjbustamante]

This Platform struct is used by the package.toml, as part of the multi-arch RFC, we are suggesting deprecating this field and adding a set of Targets.

Maybe we can add a single Target as part of this PR? here is what I did on the multi-arch PoC.

@jericop what about getting the information you need from there for buildpack packages and extensions?

[jjbustamante]

This issue is related to the following comment in the multi-arch RFC

[edmorley]

This would resolve the missing arch metadata we're seeing in our (new) multi-arch buildpack images, eg:
https://hub.docker.com/repository/docker/heroku/buildpack-go/tags

[jjbustamante]

Closing this PR, because we decided to include the implementation of the RFC 0128 with pack 0.34.0, that implementation solves the issues this PR is trying to fix.

See my comment