[Question] documentation on how to login, re-tag a multi-arch image

[Torsten Curdt]

Question

What I would like to do:

• login to ghcr.io
• re-tag a multi-arch image

There is no docker installed on the system and I am at a loss on how to use regctl registry login correctly.
It seems to insist to use docker.io

regctl registry config
{
  "docker.io": {
    "tls": "enabled",
    "hostname": "registry-1.docker.io",
    "user": "<user>",
    "credHost": "https://index.docker.io/v1/",
    "reqPerSec": 10,
    "reqConcurrent": 3
  }
}

Version

$ regctl version
VCSTag:     (devel)
VCSRef:     unknown
VCSCommit:  unknown
VCSState:   unknown
VCSDate:    unknown
Platform:   linux/arm64
GoVer:      go1.21.5
GoCompiler: gc

$ ls -la /nix/store/ | grep regctl
dr-xr-xr-x    3 root root       4096 Jan  1  1970 hq3dm22ks45g1sf2aplzma05h3c7cm4n-regclient-0.5.6-regctl

Environment

This is on nixOS on arm

Anything else

[Brandon Mitchell]

The login would be:

regctl registry login ghcr.io

It looks like you have a bad login to Docker Hub in there, which would happen if you didn't provide a registry to login to. That can be cleaned up with:

regctl registry logout

And to retag an image, that would be:

regctl image copy ghcr.io/some/image:tag-a ghcr.io/some/image:tag-b

The regctl CLI includes help for any command using --help, e.g.

$ regctl registry login --help
Provide login credentials for a registry. This may not be necessary if you
have already logged in with docker.

Usage:
  regctl registry login <registry> [flags]

Flags:
  -h, --help          help for login
  -p, --pass string   Password
      --pass-stdin    Read password from stdin
  -u, --user string   Username

Global Flags:
      --host stringArray     Registry hosts to add (reg=registry,user=username,pass=password,tls=enabled)
      --logopt stringArray   Log options
      --user-agent string    Override user agent
  -v, --verbosity string     Log level (debug, info, warn, error, fatal, panic) (default "warning")

A lot of these can probably use more details and examples. I've got that on my TODO list, and we can leave this open until that's done if you'd like.

[Torsten Curdt]

I think I might have tried just regctl registry login and totally missed the registry parameter.
That's how the docker.io got in there. I assume that's the default.

And when reading the help I couldn't really make sense of the --host which through me off.

Since I needed this for a github action I just used docker to login and regctl picked it up just fine.

The regctl image copy isn't quite the command I expected for retagging - but at least it works.
Not like docker/buildx 😠

Thanks for the help - and the tool!

Re-reading the help I should have managed to figure out the login by myself.
But the host flags could really benefit from some more details.

Feel free to close.