docker - 为什么两个 docker 镜像具有相同的镜像 ID 和相同的标签，但摘要不同？

Question

当我 docker pull hello-world 时，我得到了摘要为 f9dfddf63636d84ef479d645ab5885156ae030f611a56f3a7ac7f2fdd86d7e4e 的图像

$ docker pull hello-world
Using default tag: latest
latest: Pulling from library/hello-world
Digest: sha256:f9dfddf63636d84ef479d645ab5885156ae030f611a56f3a7ac7f2fdd86d7e4e
Status: Image is up to date for hello-world:latest
docker.io/library/hello-world:latest

我使用的是 Mac，但是当我 docker inspect hello-world:latest 时，我看到 os/arch 是 linux/amd64

    ...
    "Architecture": "amd64",
    "Os": "linux",
    ...

所以我去了https://hub.docker.com/_/hello-world/?tab=tags奇怪的是，linux/amd64 的最新 hello-world 位于 https://hub.docker.com/layers/hello-world/library/hello-world/latest/images/sha256-92c7f9c92844bbbb5d0a101b22f7c2a7949e40f8ea90c8b3bc396879d95e899a?context=explore摘要为 92c7f9c92844bbbb5d0a101b22f7c2a7949e40f8ea90c8b3bc396879d95e899a

所以我也拉下了这张图

$ docker pull hello-world@sha256:92c7f9c92844bbbb5d0a101b22f7c2a7949e40f8ea90c8b3bc396879d95e899a
sha256:92c7f9c92844bbbb5d0a101b22f7c2a7949e40f8ea90c8b3bc396879d95e899a: Pulling from library/hello-world
Digest: sha256:92c7f9c92844bbbb5d0a101b22f7c2a7949e40f8ea90c8b3bc396879d95e899a
Status: Downloaded newer image for hello-world@sha256:92c7f9c92844bbbb5d0a101b22f7c2a7949e40f8ea90c8b3bc396879d95e899a
docker.io/library/hello-world@sha256:92c7f9c92844bbbb5d0a101b22f7c2a7949e40f8ea90c8b3bc396879d95e899a

令人惊讶的是，我最终得到了两张标签相同、图像 ID 相同但摘要不同的图像。

$ docker image ls --digests
REPOSITORY                    TAG                 DIGEST                                                                    IMAGE ID            CREATED             SIZE
hello-world                   latest              sha256:92c7f9c92844bbbb5d0a101b22f7c2a7949e40f8ea90c8b3bc396879d95e899a   fce289e99eb9        15 months ago       1.84kB
hello-world                   latest              sha256:f9dfddf63636d84ef479d645ab5885156ae030f611a56f3a7ac7f2fdd86d7e4e   fce289e99eb9        15 months ago       1.84kB

这两张图片是同一张吗？如果我希望在我的团队中保持一致，我该如何唯一地处理图像？

Answer 1

hello-world 图像是一个多平台图像。每个平台都包含自己的 list ，并且有一个指向所有平台的 list 列表。这些 list 和 list 列表中的每一个都有自己的摘要。在您的列表中，docker 显示了 list 列表的摘要，以及您的特定平台 list 的摘要:

$ docker buildx imagetools inspect hello-world@sha256:f9dfddf63636d84ef479d645ab5885156ae030f611a56f3a7ac7f2fdd86d7e4e
Name:      docker.io/library/hello-world@sha256:f9dfddf63636d84ef479d645ab5885156ae030f611a56f3a7ac7f2fdd86d7e4e
MediaType: application/vnd.docker.distribution.manifest.list.v2+json
Digest:    sha256:f9dfddf63636d84ef479d645ab5885156ae030f611a56f3a7ac7f2fdd86d7e4e
           
Manifests: 
  Name:      docker.io/library/hello-world@sha256:92c7f9c92844bbbb5d0a101b22f7c2a7949e40f8ea90c8b3bc396879d95e899a
  MediaType: application/vnd.docker.distribution.manifest.v2+json
  Platform:  linux/amd64
             
  Name:      docker.io/library/hello-world@sha256:e5785cb0c62cebbed4965129bae371f0589cadd6d84798fb58c2c5f9e237efd9
  MediaType: application/vnd.docker.distribution.manifest.v2+json
  Platform:  linux/arm/v5
             
  Name:      docker.io/library/hello-world@sha256:50b8560ad574c779908da71f7ce370c0a2471c098d44d1c8f6b513c5a55eeeb1
  MediaType: application/vnd.docker.distribution.manifest.v2+json
  Platform:  linux/arm/v7
             
  Name:      docker.io/library/hello-world@sha256:963612c5503f3f1674f315c67089dee577d8cc6afc18565e0b4183ae355fb343
  MediaType: application/vnd.docker.distribution.manifest.v2+json
  Platform:  linux/arm64/v8
             
  Name:      docker.io/library/hello-world@sha256:85dc5fbe16214366748ebe9d7cc73bc42d61d19d61fe05f01e317d278c2287ed
  MediaType: application/vnd.docker.distribution.manifest.v2+json
  Platform:  linux/386
             
  Name:      docker.io/library/hello-world@sha256:8aaea2a718a29334caeaf225716284ce29dc17418edba98dbe6dafea5afcda16
  MediaType: application/vnd.docker.distribution.manifest.v2+json
  Platform:  linux/ppc64le
             
  Name:      docker.io/library/hello-world@sha256:577ad4331d4fac91807308da99ecc107dcc6b2254bc4c7166325fd01113bea2a
  MediaType: application/vnd.docker.distribution.manifest.v2+json
  Platform:  linux/s390x
             
  Name:      docker.io/library/hello-world@sha256:468a2702c410d84e275ed28dd0f46353d57d5a17f177aa7c27c2921e9ef9cd0e
  MediaType: application/vnd.docker.distribution.manifest.v2+json
  Platform:  windows/amd64
  OSVersion: 10.0.17763.1098