Docker注册表名称解析 [英] Docker Registry name resolution

问题描述

我正在为Docker Registry开发一个简单的REST客户端。对于私人注册表，名称解析非常简单。如果图像名称为 myregistry.io/myimage:latest ，则查找 https://myregistry.io/v2

I'm working on a simple REST client for Docker Registry. For private registries, name resolution is pretty simple; if the image name is myregistry.io/myimage:latest, I look for https://myregistry.io/v2 and query the API there.

但是，我注意到对于docker hub，它并不是完全有效的。如果我正在寻找 ubuntu ，可以将其扩展为 docker.io/ubuntu:latest ，但 https://docker.io/v2 返回307重定向到 https://www.docker.com/v2 ，只是返回HTML。实际的注册表终结点位于 https://registry-1.docker.io/v2 。

However, I notice that for docker hub, it doesn't quite work that way. If I'm looking for ubuntu, I can expand that to docker.io/ubuntu:latest, but https://docker.io/v2 returns a 307 redirect to https://www.docker.com/v2, which just returns HTML. The actual registry endpoint is at https://registry-1.docker.io/v2.

这只是Docker客户端中的硬编码特殊情况，还是查找我不知道的注册表端点有其他逻辑？如果只是一种特殊情况，那么比往常去 registry-1.docker.io 而不是 docker.io ？

Is this just a hardcoded special case in the docker client, or is there some extra logic to looking up registry endpoints that I'm unaware of? If it is just a special case, is there more to it than always going to registry-1.docker.io instead of docker.io?

推荐答案

中央Docker注册表是一个众所周知的特殊情况，类似于Maven Central。您可以看到默认值，例如在 https://github.com /docker/docker-ce/blob/ea449e9b10cebb259e1a43325587cd9a0e98d0ff/components/engine/registry/config.go#L42 ：

The central Docker registry is a well-known special case, similar to Maven central. You can see the defaults e.g. at https://github.com/docker/docker-ce/blob/ea449e9b10cebb259e1a43325587cd9a0e98d0ff/components/engine/registry/config.go#L42:

var (
    // DefaultNamespace is the default namespace
    DefaultNamespace = "docker.io"
    // DefaultRegistryVersionHeader is the name of the default HTTP header
    // that carries Registry version info
    DefaultRegistryVersionHeader = "Docker-Distribution-Api-Version"

    // IndexHostname is the index hostname
    IndexHostname = "index.docker.io"
    // IndexServer is used for user auth and image search
    IndexServer = "https://" + IndexHostname + "/v1/"
    // IndexName is the name of the index
    IndexName = "docker.io"

    // DefaultV2Registry is the URI of the default v2 registry
    DefaultV2Registry = &url.URL{
        Scheme: "https",
        Host:   "registry-1.docker.io",
    }
)

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