Repository name limited to 255 characters

Description

When pulling an image with a long name, I get the following error:

repository name must not be more than 255 characters

To my knowledge, this length limitation is nowhere present in the OCI Distribution Spec, where the regex for the name is defined as [a-z0-9]+((\.|_|__|-+)[a-z0-9]+)*(\/[a-z0-9]+((\.|_|__|-+)[a-z0-9]+)*)*, which doesn't impose any limit.

Certainly, the spec also specifies that:

Implementers note: Many clients impose a limit of 255 characters on the length of the concatenation of the registry hostname (and optional port), /, and value. If the registry name is registry.example.org:5000, those clients would be limited to a of 229 characters (255 minus 25 for the registry hostname and port and minus 1 for a / separator). For compatibility with those clients, registries should avoid values of that would cause this limit to be exceeded.

Which seems to be Docker's case.

But what's the rationale for this limitation? I'm hitting this limitation myself, and I'm sure I'm not alone (e.g. anyone using Nixery or similar dynamic image generation tools with long "paths" may be in the same position).

Would there be any reasons not to raise this limit as of today?

Reproduce

docker pull example.org/a/very/long/name/totaling/more/than/255/chars

Expected behavior

Image should be pulled without error.

docker version

$ docker version
Client: Docker Engine - Community
 Version:           27.1.1
 API version:       1.46
 Go version:        go1.21.12
 Git commit:        6312585
 Built:             Tue Jul 23 19:56:56 2024
 OS/Arch:           linux/amd64
 Context:           default

Server: Docker Engine - Community
 Engine:
  Version:          27.1.1
  API version:      1.46 (minimum version 1.24)
  Go version:       go1.21.12
  Git commit:       cc13f95
  Built:            Tue Jul 23 19:56:56 2024
  OS/Arch:          linux/amd64
  Experimental:     true
 containerd:
  Version:          1.7.19
  GitCommit:        2bf793ef6dc9a18e00cb12efb64355c2c9d5eb41
 runc:
  Version:          1.7.19
  GitCommit:        v1.1.13-0-g58aa920
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

docker info

Client: Docker Engine - Community
 Version:    27.1.1
 Context:    default
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.16.1
    Path:     /usr/libexec/docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  v2.29.1
    Path:     /usr/libexec/docker/cli-plugins/docker-compose

Additional Info

No response

No source file or test is identified in the issue. Start by reproducing the pull command and locating the Docker CLI's repository-name validation; review the OCI Distribution Spec compatibility note and existing tests before deciding whether the limit can change. Done means long valid repository names pull successfully without breaking compatibility.