Refactor multiarch support to go all the way to correct Architectures lines in "generate-stackbrew-library.sh"

[tianon]

See also docker-library/buildpack-deps#59, docker-library/golang#163, docker-library/docker#63, docker-library/gcc#36, jessfraz/irssi#15, redis/docker-library-redis#95.

[tianon]

This will have better output following docker-library/official-images#3041:

$ ./generate-stackbrew-library.sh
# this file is generated via https://github.com/docker-library/openjdk/blob/efbcd4f8e42e510ef561a7ce518633f0eba33992/generate-stackbrew-library.sh

Maintainers: Tianon Gravi <[email protected]> (@tianon),
             Joseph Ferguson <[email protected]> (@yosifkit)
GitRepo: https://github.com/docker-library/openjdk.git

Tags: 6b38-jdk, 6b38, 6-jdk, 6
Architectures: amd64, arm32v7, i386
GitCommit: bd3c2a9867c9dc6a9a8425a8df5c54edf0cbf2cc
Directory: 6-jdk

Tags: 6b38-jre, 6-jre
Architectures: amd64, arm32v7, i386
GitCommit: bd3c2a9867c9dc6a9a8425a8df5c54edf0cbf2cc
Directory: 6-jre

Tags: 7u131-jdk, 7u131, 7-jdk, 7
Architectures: amd64, arm32v7, arm64v8, i386, ppc64le, s390x
GitCommit: 93316d3b14379d29fe0cd363bd6839eb8dd8cc7b
Directory: 7-jdk

Tags: 7u131-jdk-alpine, 7u131-alpine, 7-jdk-alpine, 7-alpine
Architectures: amd64
GitCommit: 43e145f3fc5fd98a141f0c1c6fe90b9ea93977da
Directory: 7-jdk/alpine

Tags: 7u131-jre, 7-jre
Architectures: amd64, arm32v7, arm64v8, i386, ppc64le, s390x
GitCommit: 93316d3b14379d29fe0cd363bd6839eb8dd8cc7b
Directory: 7-jre

Tags: 7u131-jre-alpine, 7-jre-alpine
Architectures: amd64
GitCommit: 43e145f3fc5fd98a141f0c1c6fe90b9ea93977da
Directory: 7-jre/alpine

Tags: 8u131-jdk, 8u131, 8-jdk, 8, jdk, latest
Architectures: amd64, arm32v7, arm64v8, i386, ppc64le, s390x
GitCommit: 415b0cc42d91ef5d70597d8a24d942967728242b
Directory: 8-jdk

Tags: 8u131-jdk-alpine, 8u131-alpine, 8-jdk-alpine, 8-alpine, jdk-alpine, alpine
Architectures: amd64
GitCommit: 43e145f3fc5fd98a141f0c1c6fe90b9ea93977da
Directory: 8-jdk/alpine

Tags: 8u131-jdk-windowsservercore, 8u131-windowsservercore, 8-jdk-windowsservercore, 8-windowsservercore, jdk-windowsservercore, windowsservercore
Architectures: windows-amd64
GitCommit: 9745c87a15896ec558429a826e23926e721e4846
Directory: 8-jdk/windows/windowsservercore
Constraints: windowsservercore

Tags: 8u131-jdk-nanoserver, 8u131-nanoserver, 8-jdk-nanoserver, 8-nanoserver, jdk-nanoserver, nanoserver
Architectures: windows-amd64
GitCommit: 9745c87a15896ec558429a826e23926e721e4846
Directory: 8-jdk/windows/nanoserver
Constraints: nanoserver

Tags: 8u131-jre, 8-jre, jre
Architectures: amd64, arm32v7, arm64v8, i386, ppc64le, s390x
GitCommit: 415b0cc42d91ef5d70597d8a24d942967728242b
Directory: 8-jre

Tags: 8u131-jre-alpine, 8-jre-alpine, jre-alpine
Architectures: amd64
GitCommit: 43e145f3fc5fd98a141f0c1c6fe90b9ea93977da
Directory: 8-jre/alpine

Tags: 9-b170-jdk, 9-b170, 9-jdk, 9
Architectures: amd64, arm32v7, arm64v8, i386, ppc64le, s390x
GitCommit: c34391ea981c804c097981bad8403ec4bd934285
Directory: 9-jdk

Tags: 9-b170-jre, 9-jre
Architectures: amd64, arm32v7, arm64v8, i386, ppc64le, s390x
GitCommit: c34391ea981c804c097981bad8403ec4bd934285
Directory: 9-jre

[md5]

@tianon Do you have any guidance on how to support this in derived images? I'd like to make any changes necessary to the jetty image. It looks like we just need to add an Architectures line to the library file and update our generate-stackbrew-library.sh similar to what was done here?

[tianon]

@md5 yeah, if Jetty supports other arches (which would make sense, given its Java base 😄), adding an appropriate Architectures line similar to these should do the trick! There are a number of good examples now (cross-linked around here, but all linked from docker-library/buildpack-deps#59) which have varying degrees of support for multiarch (either same arches as their parent or a subset) 👍

(I'd just ask that you test on at least i386 by modifying your FROM locally to include i386/... to ensure that at least the basic functionality works on another arch, but preferably test on all the arches you end up including if you can. 😅)