buildah tag ruins manifest lists

[cevich]

Description

When I build a multi-arch manifest list, sometimes I want to call or push it using multiple names. Intuitively, the tag subcommand strikes me as the one to use, but doesn't seem to do the right thing.

Steps to reproduce the issue:

1. $ buildah bud --layers --force-rm --jobs 12 --platform=linux/amd64 --manifest localhost/foo/bar:latest /path/to/context
2. $ buildah tag localhost/foo/bar:latest localhost/foo/bar:9.8.7-testing
3. $ buildah images

Describe the results you received:

REPOSITORY                                  TAG             IMAGE ID       CREATED         SIZE
localhost/foo/bar                           latest          e2c1204b1afd   7 minutes ago   547 B
localhost/foo/bar                           9.8.7-testing   e62f975862e7   7 minutes ago   119 MB

Describe the results you expected:

REPOSITORY                                  TAG             IMAGE ID       CREATED         SIZE
localhost/foo/bar                           latest          e2c1204b1afd   7 minutes ago   547 B
localhost/foo/bar                           9.8.7-testing   e2c1204b1afd   7 minutes ago   547 B

Output of rpm -q buildah or apt list buildah:

N/A compiled from source 197b9a1

Output of buildah version:

Version:         1.23.0-dev
Go Version:      go1.15.14
Image Spec:      1.0.1-dev
Runtime Spec:    1.0.2-dev
CNI Spec:        0.4.0
libcni Version:  v0.8.1
image Version:   5.15.1
Git Commit:      197b9a1f
Built:           Thu Aug 19 14:14:58 2021
OS/Arch:         linux/amd64
BuildPlatform:   linux/amd64

Output of podman version if reporting a podman build issue:

N/A

Output of cat /etc/*release:

NAME=Fedora
VERSION="33 (Workstation Edition)"
ID=fedora
VERSION_ID=33
VERSION_CODENAME=""
PLATFORM_ID="platform:f33"
PRETTY_NAME="Fedora 33 (Workstation Edition)"
ANSI_COLOR="0;38;2;60;110;180"
LOGO=fedora-logo-icon
CPE_NAME="cpe:/o:fedoraproject:fedora:33"
HOME_URL="https://fedoraproject.org/"
DOCUMENTATION_URL="https://docs.fedoraproject.org/en-US/fedora/f33/system-administrators-guide/"
SUPPORT_URL="https://fedoraproject.org/wiki/Communicating_and_getting_help"
BUG_REPORT_URL="https://bugzilla.redhat.com/"
REDHAT_BUGZILLA_PRODUCT="Fedora"
REDHAT_BUGZILLA_PRODUCT_VERSION=33
REDHAT_SUPPORT_PRODUCT="Fedora"
REDHAT_SUPPORT_PRODUCT_VERSION=33
PRIVACY_POLICY_URL="https://fedoraproject.org/wiki/Legal:PrivacyPolicy"
VARIANT="Workstation Edition"
VARIANT_ID=workstation

Output of uname -a:

Linux fedora 5.12.17-200.fc33.x86_64 #1 SMP Thu Jul 15 12:41:55 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

Output of cat /etc/containers/storage.conf:

Default that comes from installing rpms

[cevich]

Note: For my use-case, I would be perfectly happy using a buildah manifest tag subcommand if it were available. Regular users though, they might expect buildah tag to work, so maybe print a warning if the source is a manifest list?

[rhatdan]

@flouthoc PTAL

[flouthoc]

/assign

[flouthoc]

@cevich @rhatdan So afaik builah tag actually fetches the relevant image from the manifest list and tags it which seems to be the expected behavior since that is what manifest was supposed to do. I am in favor of buildah manifest tag but would love your opinions on this.

[rhatdan]

I am fine with manifest tag.

How does buildah tag figure out which image is relavent? IE If I have a list with multiple images, will it tag them all, or just the first one it finds.

[rhatdan]

Or the one that matches the current arch?

[flouthoc]

@rhatdan It takes image options if nothing is provided it gets arch value from runtime context i.e r.systemContext.ArchitectureChoice and creates image for particular architecture.

[flouthoc]

@cevich @rhatdan Going ahead with buildah manifest tag.

[nalind]

Are we going to come back and retrofit tag later, like we did with buildah push?

[flouthoc]

@nalind I missing context on retrofit about buildah push 😅 . Would love to hear what's your take on buildah manifest tag do you think its a good idea or should we have support for tagging manifest list in buildah tag itself.

[nalind]

The retrofit for buildah push was done in #2895, and the reasoning given for it and #2894 agrees with #3467 (comment). If we're going to reverse course and do the same thing here later, we might as get it over with now.

[flouthoc]

@nalind @rhatdan I was not aware of previous threads but i guess from what it seems I think i should move with buildah tag instead of buildah manifest tag inorder to prevent rework or retrofits. WDYT

[rhatdan]

I am fine with buildah tag == buildah manifest tag.

[flouthoc]

Following PR's should close this #3483 & containers/common#747