我可以在没有下载图像的情况下获得图像摘要吗？ [英] Can I get an image digest without downloading the image?
问题描述
类似于什么是sha256代码码头图像？，我想找到一个Docker图像的摘要。下载图片时，可以看到摘要：
Similar to the question "What´s the sha256 code of a docker image?", I would like to find the digest of a Docker image. I can see the digest when I download an image:
$ docker pull waisbrot/wait:latest
latest: Pulling from waisbrot/wait
Digest: sha256:6f2185daa4ab1711181c30d03f565508e8e978ebd0f263030e7de98deee5f330
Status: Image is up to date for waisbrot/wait:latest
$
另一个问题，什么是Docker注册表v2 API端点以获取图像的摘要有一个答案建议 Docker-Content-Digest 标题。
Another question, What is the Docker registry v2 API endpoint to get the digest for an image has an answer suggesting the Docker-Content-Digest header.
我可以看到有一个 Docker-Content-Digest 标题当我获取图像的清单时：
I can see that there is a Docker-Content-Digest header when I fetch the manifest for the image:
$ curl 'https://auth.docker.io/token?service=registry.docker.io&scope=repository:waisbrot/wait:pull' -H "Authorization: Basic ${username_password_base64}"
# store the resulting token in DT
$ curl -v https://registry-1.docker.io/v2/waisbrot/wait/manifests/latest -H "Authorization: Bearer $DT" -XHEAD
* Trying 52.7.141.30...
* Connected to registry-1.docker.io (52.7.141.30) port 443 (#0)
* TLS 1.2 connection using TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
* Server certificate: *.docker.io
* Server certificate: RapidSSL SHA256 CA - G3
* Server certificate: GeoTrust Global CA
> GET /v2/waisbrot/wait/manifests/latest HTTP/1.1
> Host: registry-1.docker.io
> User-Agent: curl/7.43.0
> Accept: */*
> Authorization: Bearer LtVRw-etc-etc-etc
>
< HTTP/1.1 200 OK
< Content-Length: 4974
< Content-Type: application/vnd.docker.distribution.manifest.v1+prettyjws
< Docker-Content-Digest: sha256:128c6e3534b842a2eec139999b8ce8aa9a2af9907e2b9269550809d18cd832a3
< Docker-Distribution-Api-Version: registry/2.0
< Etag: "sha256:128c6e3534b842a2eec139999b8ce8aa9a2af9907e2b9269550809d18cd832a3"
< Date: Wed, 07 Sep 2016 16:37:15 GMT
< Strict-Transport-Security: max-age=31536000
但是，这个标题是不一样的。 pull 命令得到我 6f21 ，标题显示 128c 。此外，pull命令对于该摘要不起作用：
However, this header isn't the same. The pull command got me 6f21 and the header shows 128c. Further, the pull command doesn't work for that digest:
$ docker pull waisbrot/wait@sha256:128c6e3534b842a2eec139999b8ce8aa9a2af9907e2b9269550809d18cd832a3
Error response from daemon: manifest unknown: manifest unknown
而当我有正确的摘要：
$ docker pull waisbrot/wait@sha256:6f2185daa4ab1711181c30d03f565508e8e978ebd0f263030e7de98deee5f330 12:46 waisbrot@influenza
sha256:6f2185daa4ab1711181c30d03f565508e8e978ebd0f263030e7de98deee5f330: Pulling from waisbrot/wait
Digest: sha256:6f2185daa4ab1711181c30d03f565508e8e978ebd0f263030e7de98deee5f330
Status: Image is up to date for waisbrot/wait@sha256:6f2185daa4ab1711181c30d03f565508e8e978ebd0f263030e7de98deee5f330
我正在寻找的是一种方式来翻译最新的标签（其中更改所有的时间）成为一个固定的摘要，我可以可靠地拉。但是我不想真的把它拉下来做这个翻译。
What I'm looking for is a way to translate the latest tag (which changes all the time) into a fixed digest that I can reliably pull. But I don't want to actually pull it down in order to do this translation.
推荐答案
尝试
$ curl -H "Accept: application/vnd.docker.distribution.manifest.v2+json" 'https://auth.docker.io/token?service=registry.docker.io&scope=repository:waisbrot/wait:pull' -H "Authorization: Basic ${username_password_base64}"
背景：这个论坛链接正在讨论同样的问题。
Background: This forum link is discussing the same issue.
问题是服务器选择的默认内容类型是 application / vnd.docker.distribution.manifest.v1 + prettyjws （v1版本），您需要v2清单。因此，您需要将接受标头设置为 application / vnd.docker.distribution.manifest.v2 + json 。
The problem is that the default content-type being selected by the server is application/vnd.docker.distribution.manifest.v1+prettyjws (a v1 manifest) and you need to v2 manifest. Therefore, you need to set the Accept header to application/vnd.docker.distribution.manifest.v2+json.
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