Pre-reqs for docker use: image is public, so docker pull errors likely mean expired token

[ismith]

To pull the image, you need docker to be logged in to ghcr.io; this PR links in the README to instructions for doing that.

[Copilot]

Pull Request Overview

This PR updates the prerequisites section in the README to include instructions for logging into GitHub Container Registry (ghcr.io) for Docker users.

• Updated the Docker prerequisites to mention ghcr.io authentication.
• Added a direct link to the GitHub documentation on authenticating with a personal access token.

[SamMorrowDrums]

Huh, is this correct? @juruen you validated that anonymous docker pull should just work right?

I've also added this to other machines and scripts and had it pull without authentication. I'm wondering what issue you are experiencing here.

[juruen]

Huh, is this correct? @juruen you validated that anonymous docker pull should just work right?

@SamMorrowDrums Yup. I validated it in two ways:

• brand new vm that never did a docker login to any registries
• docker logout ghcr.io and docker pull on another vm

See #192 (comment)

A docker logout ghcr.io helped that user. So maybe users who are logged into ghcr.io with an expired token are experiencing these issues.

@ismith could you try this:

docker logout ghcr.io
docker pull ghcr.io/github/github-mcp-server

[SamMorrowDrums]

users who are logged into ghcr.io with a expired token are experiencing these issues.

Your docker registry was so preoccupied with whether or not they could validate your token, they didn't stop to think if they should.

[williammartin]

@ismith if #282 (comment) is correct, could you update this PR to the effect of "the image is public, so if you're getting errors, it's probably because your token is expired"

[williammartin]

Gentle nudge @ismith.