Docker执行pull做了什么

作者出版于 Docker Container

2019-12-11 约 3308 字预计阅读 7 分钟

Docker manifest

mediaType

在下面后面的文章中需要注意到mediaType对应的值，其代表了文件的类型，在规范中定义了以下类型：

application/vnd.docker.distribution.manifest.v1+json: 代表了第一个版本的manifest格式，已经出现了第二个版本了(schemaVersion = 1)
application/vnd.docker.distribution.manifest.v2+json: 代表了新版本的manifest格式 (schemaVersion = 2)
application/vnd.docker.distribution.manifest.list.v2+json: Manifest list，也就是上方示例的manifest list文件
application/vnd.docker.container.image.v1+json: Container config JSON
application/vnd.docker.image.rootfs.diff.tar.gzip: “Layer”, as a gzipped tar，代表了镜像层的压缩类型
application/vnd.docker.image.rootfs.foreign.diff.tar.gzip: “Layer”, as a gzipped tar that should never be pushed，
application/vnd.docker.plugin.v1+json: Plugin config JSON

Image Manifest

Image Manifest提供了容器镜像的配置和镜像层的信息：

{
    "config": {
        "digest": "sha256:775349758637aff77bf85e2ff0597e86e3e859183ef0baba8b3e8fc8d3cba51c",
        "mediaType": "application/vnd.docker.container.image.v1+json",
        "size": 3411
    },
    "layers": [
        {
            "digest": "sha256:7ddbc47eeb70dc7f08e410a6667948b87ff3883024eb41478b44ef9a81bf400c",
            "mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
            "size": 26688847
        },
        {
            "digest": "sha256:c1bbdc448b7263673926b8fe2e88491e5083a8b4b06ddfabf311f2fc5f27e2ff",
            "mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
            "size": 35362
        },
        {
            "digest": "sha256:8c3b70e3904492c753652606df4726430426f42ea56e06ea924d6fea7ae162a1",
            "mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
            "size": 845
        },
        {
            "digest": "sha256:45d437916d5781043432f2d72608049dcf74ddbd27daa01a25fa63c8f1b9adc4",
            "mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
            "size": 162
        }
    ],
    "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
    "schemaVersion": 2
}

说明：

config：包含了镜像配置信息
- mediaType: 其代表了文件的类型，详情看上方的mediaType
- size：对象的字节大小。存在此字段，以便客户端在验证之前具有预期的内容大小。如果检索到的内容的长度与指定的长度不匹配，则不应信任该内容。
- digest：代表了一个文件的sha256的哈希校验值。其实就是对一个HTTP请求的返回结果进行sha256。
layers：包含了所有所有镜像层
- mediaType：引用对象的MIME类型。通常应该是application/vnd.docker.image.rootfs.diff.tar.gzip
- size：对象的字节大小。存在此字段，以便客户端在验证之前具有预期的内容大小。如果检索到的内容的长度与指定的长度不匹配，则不应信任该内容。
- digest：代表了镜像层的sha256的哈希校验值。在下面的演示中可以明确的看到

Manifest List

我们都知道镜像有amd64、arm、ppc64le等架构的镜像，而且还会区分操作系统，但是我们在拉去镜像的时候并没有标明拉去amd64还是arm64的已经linux，这就是靠manifest list文件来实现的。在我们拉去镜像的时候，docker引擎会先去获取Manifest List文件，查看有没有符合CPU架构和OS等要求的镜像，然后拉去相应的镜像。

Ubuntu镜像的manifest list文件：

{
    "manifests": [
        {
            "digest": "sha256:134c7fe821b9d359490cd009ce7ca322453f4f2d018623f849e580a89a685e5d",
            "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
            "platform": {
                "architecture": "amd64",
                "os": "linux"
            },
            "size": 1152
        },
        {
            "digest": "sha256:349e3988c0241304b39218794b8263325f7dc517317e00be37d43c3bdda9449b",
            "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
            "platform": {
                "architecture": "arm",
                "os": "linux",
                "variant": "v7"
            },
            "size": 1152
        },
        {
            "digest": "sha256:a8878539376d57d89dc7e8034dd8ecb16ebce4693da48b0d8ea2890efd097848",
            "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
            "platform": {
                "architecture": "arm64",
                "os": "linux",
                "variant": "v8"
            },
            "size": 1152
        },
        {
            "digest": "sha256:bcf9d02754f659706860d04fd261207db010db96e782e2eb5d5bbd7168388b89",
            "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
            "platform": {
                "architecture": "386",
                "os": "linux"
            },
            "size": 1152
        },
        {
            "digest": "sha256:746e11f60338e1413daa698cdc052f5428fdbddacefb4bae23e4b6ae0c8231e5",
            "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
            "platform": {
                "architecture": "ppc64le",
                "os": "linux"
            },
            "size": 1152
        },
        {
            "digest": "sha256:391556555751770ffbcebbce4ed539454cea660c0be0a726f801c96f353a22e0",
            "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
            "platform": {
                "architecture": "s390x",
                "os": "linux"
            },
            "size": 1152
        }
    ],
    "mediaType": "application/vnd.docker.distribution.manifest.list.v2+json",
    "schemaVersion": 2
}

在上方示例中，manifests列表中所有子项都代表了一个不同架构的镜像，每个镜像对应了上面讲的Image Manifest

platform描述了清单中的图像所运行的平台。有效的操作系统。其他选项说明：

digest：代表了一个文件的sha256的哈希校验值。其实该值对应的就是上方说的Image Manifest整个文件的校验值。
size：对象字节大小，以便客户端在验证之前有一个预期的大小。
platform->architecture：描述了该镜像的CPU架构。
platform->os：描述了该镜像的操作系统。

建议去下面的官网参考链接简单的过一下。

参考：

https://docs.docker.com/registry/spec/manifest-v2-2/

拉取镜像的全部步骤

下面的例子以ubuntu:latest的镜像来演示

访问docker的公共仓库，会返回401认证错误，Www-Authenticate头会返回一个获取token的地址realm，已经service的字符串为registry.docker.io

# curl -i https://registry-1.docker.io/v2/
HTTP/1.1 200 Connection established

HTTP/1.1 401 Unauthorized
Content-Type: application/json
Docker-Distribution-Api-Version: registry/2.0
Www-Authenticate: Bearer realm="https://auth.docker.io/token",service="registry.docker.io"
Date: Wed, 11 Dec 2019 07:35:02 GMT
Content-Length: 87
Strict-Transport-Security: max-age=31536000

{"errors":[{"code":"UNAUTHORIZED","message":"authentication required","detail":null}]}

访问上一步请求的realm地址，构造一个URL <realm>?service=<service>&scope=repository:library/ubuntu:pull

<realm>替换为上个请求Www-Authenticate返回的realm的值
<service>替换为上个请求Www-Authenticate返回的service的值
repository: 后面替换为镜像的仓库/镜像名称:pull

下面的操作以library/ubuntu:latest为例

# curl 'https://auth.docker.io/token?service=registry.docker.io&scope=repository:library/ubuntu:pull'
{"token":"eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCIsIng1YyI6WyJNSUlDK2pDQ0FwK2dBd0lCQWdJQkFEQUtCZ2dxaGtqT1BRUURBakJHTVVRd1FnWURWUVFERXpzeVYwNVpPbFZMUzFJNlJFMUVVanBTU1U5Rk9reEhOa0U2UTFWWVZEcE5SbFZNT2tZelNFVTZOVkF5VlRwTFNqTkdPa05CTmxrNlNrbEVVVEFlRncweE9UQXhNVEl3TURJeU5EVmFGdzB5TURBeE1USXdNREl5TkRWYU1FWXhSREJDQmdOVkJBTVRPMUpMTkZNNlMwRkxVVHBEV0RWRk9rRTJSMVE2VTBwTVR6cFFNbEpMT2tOWlZVUTZTMEpEU0RwWFNVeE1Pa3hUU2xrNldscFFVVHBaVWxsRU1JSUJJakFOQmdrcWhraUc5dzBCQVFFRkFBT0NBUThBTUlJQkNnS0NBUUVBcjY2bXkveXpHN21VUzF3eFQ3dFplS2pqRzcvNnBwZFNMY3JCcko5VytwcndzMGtIUDVwUHRkMUpkcFdEWU1OZWdqQXhpUWtRUUNvd25IUnN2ODVUalBUdE5wUkdKVTRkeHJkeXBvWGc4TVhYUEUzL2lRbHhPS2VNU0prNlRKbG5wNGFtWVBHQlhuQXRoQzJtTlR5ak1zdFh2ZmNWN3VFYWpRcnlOVUcyUVdXQ1k1Ujl0a2k5ZG54Z3dCSEF6bG8wTzJCczFmcm5JbmJxaCtic3ZSZ1FxU3BrMWhxYnhSU3AyRlNrL2tBL1gyeUFxZzJQSUJxWFFMaTVQQ3krWERYZElJczV6VG9ZbWJUK0pmbnZaMzRLcG5mSkpNalpIRW4xUVJtQldOZXJZcVdtNVhkQVhUMUJrQU9aditMNFVwSTk3NFZFZ2ppY1JINVdBeWV4b1BFclRRSURBUUFCbzRHeU1JR3ZNQTRHQTFVZER3RUIvd1FFQXdJSGdEQVBCZ05WSFNVRUNEQUdCZ1JWSFNVQU1FUUdBMVVkRGdROUJEdFNTelJUT2t0QlMxRTZRMWcxUlRwQk5rZFVPbE5LVEU4NlVESlNTenBEV1ZWRU9rdENRMGc2VjBsTVREcE1VMHBaT2xwYVVGRTZXVkpaUkRCR0JnTlZIU01FUHpBOWdEc3lWMDVaT2xWTFMxSTZSRTFFVWpwU1NVOUZPa3hITmtFNlExVllWRHBOUmxWTU9rWXpTRVU2TlZBeVZUcExTak5HT2tOQk5sazZTa2xFVVRBS0JnZ3Foa2pPUFFRREFnTkpBREJHQWlFQXFOSXEwMFdZTmM5Z2tDZGdSUzRSWUhtNTRZcDBTa05Rd2lyMm5hSWtGd3dDSVFEMjlYdUl5TmpTa1cvWmpQaFlWWFB6QW9TNFVkRXNvUUhyUVZHMDd1N3ZsUT09Il19.eyJhY2Nlc3MiOlt7InR5cGUiOiJyZXBvc2l0b3J5IiwibmFtZSI6ImxpYnJhcnkvdWJ1bnR1IiwiYWN0aW9ucyI6WyJwdWxsIl19XSwiYXVkIjoicmVnaXN0cnkuZG9ja2VyLmlvIiwiZXhwIjoxNTc2MDUxNzYyLCJpYXQiOjE1NzYwNTE0NjIsImlzcyI6ImF1dGguZG9ja2VyLmlvIiwianRpIjoiRllrY3lBWVFGeUdNNXhtRmI2cjEiLCJuYmYiOjE1NzYwNTExNjIsInN1YiI6IiJ9.I_sr5aBFEluPyz8JKDnkgCQ3jKrnifNvBg1OD4Ny6PcKwqwCaNzbB3LWII1SrL3LvYp3ztAGG_sEAgzb8LbkCXbd51xzk1FmCKwV6rbd2TZ4AWmfE8OHaBvHuTR0IcvX2PBUC1VuE2LLTsr2Dt0leq3s4hi5-3A_8_XSmau6XRLtaEImhsR3HJUGPzDbupq5iL4LYUle-lW75wBm-QtANjjF9qsnjNMFltlij8XvWe0ADv-bYtGA_bGUAz_PVu2IIenNSsxMiuBzMNGTyXnCepBgAqXuoF8gFJHgZ0Cli2YakBDNsU9BA5STvtDxaLXQaUIncjo2KfJZtl19TVLOog","access_token":"eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCIsIng1YyI6WyJNSUlDK2pDQ0FwK2dBd0lCQWdJQkFEQUtCZ2dxaGtqT1BRUURBakJHTVVRd1FnWURWUVFERXpzeVYwNVpPbFZMUzFJNlJFMUVVanBTU1U5Rk9reEhOa0U2UTFWWVZEcE5SbFZNT2tZelNFVTZOVkF5VlRwTFNqTkdPa05CTmxrNlNrbEVVVEFlRncweE9UQXhNVEl3TURJeU5EVmFGdzB5TURBeE1USXdNREl5TkRWYU1FWXhSREJDQmdOVkJBTVRPMUpMTkZNNlMwRkxVVHBEV0RWRk9rRTJSMVE2VTBwTVR6cFFNbEpMT2tOWlZVUTZTMEpEU0RwWFNVeE1Pa3hUU2xrNldscFFVVHBaVWxsRU1JSUJJakFOQmdrcWhraUc5dzBCQVFFRkFBT0NBUThBTUlJQkNnS0NBUUVBcjY2bXkveXpHN21VUzF3eFQ3dFplS2pqRzcvNnBwZFNMY3JCcko5VytwcndzMGtIUDVwUHRkMUpkcFdEWU1OZWdqQXhpUWtRUUNvd25IUnN2ODVUalBUdE5wUkdKVTRkeHJkeXBvWGc4TVhYUEUzL2lRbHhPS2VNU0prNlRKbG5wNGFtWVBHQlhuQXRoQzJtTlR5ak1zdFh2ZmNWN3VFYWpRcnlOVUcyUVdXQ1k1Ujl0a2k5ZG54Z3dCSEF6bG8wTzJCczFmcm5JbmJxaCtic3ZSZ1FxU3BrMWhxYnhSU3AyRlNrL2tBL1gyeUFxZzJQSUJxWFFMaTVQQ3krWERYZElJczV6VG9ZbWJUK0pmbnZaMzRLcG5mSkpNalpIRW4xUVJtQldOZXJZcVdtNVhkQVhUMUJrQU9aditMNFVwSTk3NFZFZ2ppY1JINVdBeWV4b1BFclRRSURBUUFCbzRHeU1JR3ZNQTRHQTFVZER3RUIvd1FFQXdJSGdEQVBCZ05WSFNVRUNEQUdCZ1JWSFNVQU1FUUdBMVVkRGdROUJEdFNTelJUT2t0QlMxRTZRMWcxUlRwQk5rZFVPbE5LVEU4NlVESlNTenBEV1ZWRU9rdENRMGc2VjBsTVREcE1VMHBaT2xwYVVGRTZXVkpaUkRCR0JnTlZIU01FUHpBOWdEc3lWMDVaT2xWTFMxSTZSRTFFVWpwU1NVOUZPa3hITmtFNlExVllWRHBOUmxWTU9rWXpTRVU2TlZBeVZUcExTak5HT2tOQk5sazZTa2xFVVRBS0JnZ3Foa2pPUFFRREFnTkpBREJHQWlFQXFOSXEwMFdZTmM5Z2tDZGdSUzRSWUhtNTRZcDBTa05Rd2lyMm5hSWtGd3dDSVFEMjlYdUl5TmpTa1cvWmpQaFlWWFB6QW9TNFVkRXNvUUhyUVZHMDd1N3ZsUT09Il19.eyJhY2Nlc3MiOlt7InR5cGUiOiJyZXBvc2l0b3J5IiwibmFtZSI6ImxpYnJhcnkvdWJ1bnR1IiwiYWN0aW9ucyI6WyJwdWxsIl19XSwiYXVkIjoicmVnaXN0cnkuZG9ja2VyLmlvIiwiZXhwIjoxNTc2MDUxNzYyLCJpYXQiOjE1NzYwNTE0NjIsImlzcyI6ImF1dGguZG9ja2VyLmlvIiwianRpIjoiRllrY3lBWVFGeUdNNXhtRmI2cjEiLCJuYmYiOjE1NzYwNTExNjIsInN1YiI6IiJ9.I_sr5aBFEluPyz8JKDnkgCQ3jKrnifNvBg1OD4Ny6PcKwqwCaNzbB3LWII1SrL3LvYp3ztAGG_sEAgzb8LbkCXbd51xzk1FmCKwV6rbd2TZ4AWmfE8OHaBvHuTR0IcvX2PBUC1VuE2LLTsr2Dt0leq3s4hi5-3A_8_XSmau6XRLtaEImhsR3HJUGPzDbupq5iL4LYUle-lW75wBm-QtANjjF9qsnjNMFltlij8XvWe0ADv-bYtGA_bGUAz_PVu2IIenNSsxMiuBzMNGTyXnCepBgAqXuoF8gFJHgZ0Cli2YakBDNsU9BA5STvtDxaLXQaUIncjo2KfJZtl19TVLOog","expires_in":300,"issued_at":"2019-12-11T08:04:22.207624154Z"}

可以看到上面返回一大串json格式的字符出，只需要保留token对应的值即可，下面的所有请求都要在请求头中带上token对应的值

下面开始获取Manifest List文件

其实在操作时这一步是可以省略的，但是为了更好的理解对应关系，建议还是看下比较好！

获取Manifest List文件需要在Accept中设置mediaType，正是上面提过的mediaType，需要设置为application/vnd.docker.distribution.manifest.list.v2+json

# head_auth="Authorization: Bearer ${TOKEN}"                                           # 注意替换TOKEN的内容
# head_accept='Accept: application/vnd.docker.distribution.manifest.list.v2+json'
# curl -i -H "$head_auth" -H "$head_accept" 'https://registry-1.docker.io/v2/library/ubuntu/manifests/latest'
HTTP/1.1 200 Connection Established

HTTP/1.1 200 OK
Content-Length: 1418
Content-Type: application/vnd.docker.distribution.manifest.list.v2+json
Docker-Content-Digest: sha256:6e9f67fa63b0323e9a1e587fd71c561ba48a034504fb804fd26fd8800039835d
Docker-Distribution-Api-Version: registry/2.0
Etag: "sha256:6e9f67fa63b0323e9a1e587fd71c561ba48a034504fb804fd26fd8800039835d"
Date: Wed, 11 Dec 2019 13:42:59 GMT
Strict-Transport-Security: max-age=31536000

{
    "manifests": [
        {
            "digest": "sha256:134c7fe821b9d359490cd009ce7ca322453f4f2d018623f849e580a89a685e5d",
            "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
            "platform": {
                "architecture": "amd64",
                "os": "linux"
            },
            "size": 1152
        },
        {
            "digest": "sha256:349e3988c0241304b39218794b8263325f7dc517317e00be37d43c3bdda9449b",
            "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
            "platform": {
                "architecture": "arm",
                "os": "linux",
                "variant": "v7"
            },
            "size": 1152
        },
        {
            "digest": "sha256:a8878539376d57d89dc7e8034dd8ecb16ebce4693da48b0d8ea2890efd097848",
            "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
            "platform": {
                "architecture": "arm64",
                "os": "linux",
                "variant": "v8"
            },
            "size": 1152
        },
        {
            "digest": "sha256:bcf9d02754f659706860d04fd261207db010db96e782e2eb5d5bbd7168388b89",
            "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
            "platform": {
                "architecture": "386",
                "os": "linux"
            },
            "size": 1152
        },
        {
            "digest": "sha256:746e11f60338e1413daa698cdc052f5428fdbddacefb4bae23e4b6ae0c8231e5",
            "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
            "platform": {
                "architecture": "ppc64le",
                "os": "linux"
            },
            "size": 1152
        },
        {
            "digest": "sha256:391556555751770ffbcebbce4ed539454cea660c0be0a726f801c96f353a22e0",
            "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
            "platform": {
                "architecture": "s390x",
                "os": "linux"
            },
            "size": 1152
        }
    ],
    "mediaType": "application/vnd.docker.distribution.manifest.list.v2+json",
    "schemaVersion": 2
}

注意：为了方便观看，上方返回的json我做了格式化处理。

说明：

上方URL中的library/ubuntu替换为你的镜像仓库和镜像名称。
上方URL中的latest为镜像的tag，替换成相应的即可。
返回结果的Header中的Docker-Content-Digest，正是ubuntu:latest的Digest的值，那么这个值是从哪来的呢？正是本次请求返回内容的sha256的校验和。

其他该文件的具体内容也就不解释了，上方已经解释过了，这里需要注意一下amd64的digest，下面我们请求image manifest的返回的内容的sha256的校验和正是这个值。

获取Image Manifest

请求Image Manifest内容和请求Manifest的方式是一样的，只需要修改mediaType的类型为application/vnd.docker.distribution.manifest.v2+json

# head_accept='Accept: application/vnd.docker.distribution.manifest.v2+json'
# head_auth="Authorization: Bearer ${TOKEN}"                                           # 注意替换TOKEN的内容
# curl -i -H "$head_auth" -H "$head_accept" 'https://registry-1.docker.io/v2/library/ubuntu/manifests/latest'
HTTP/1.1 200 Connection Established

HTTP/1.1 200 OK
Content-Length: 1152
Content-Type: application/vnd.docker.distribution.manifest.v2+json
Docker-Content-Digest: sha256:134c7fe821b9d359490cd009ce7ca322453f4f2d018623f849e580a89a685e5d
Docker-Distribution-Api-Version: registry/2.0
Etag: "sha256:134c7fe821b9d359490cd009ce7ca322453f4f2d018623f849e580a89a685e5d"
Date: Wed, 11 Dec 2019 13:54:05 GMT
Strict-Transport-Security: max-age=31536000

{
   "schemaVersion": 2,
   "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
   "config": {
      "mediaType": "application/vnd.docker.container.image.v1+json",
      "size": 3411,
      "digest": "sha256:775349758637aff77bf85e2ff0597e86e3e859183ef0baba8b3e8fc8d3cba51c"
   },
   "layers": [
      {
         "mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
         "size": 26688847,
         "digest": "sha256:7ddbc47eeb70dc7f08e410a6667948b87ff3883024eb41478b44ef9a81bf400c"
      },
      {
         "mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
         "size": 35362,
         "digest": "sha256:c1bbdc448b7263673926b8fe2e88491e5083a8b4b06ddfabf311f2fc5f27e2ff"
      },
      {
         "mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
         "size": 845,
         "digest": "sha256:8c3b70e3904492c753652606df4726430426f42ea56e06ea924d6fea7ae162a1"
      },
      {
         "mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
         "size": 162,
         "digest": "sha256:45d437916d5781043432f2d72608049dcf74ddbd27daa01a25fa63c8f1b9adc4"
      }
   ]
}

说明：

上方URL中的library/ubuntu替换为你的镜像仓库和镜像名称。
上方URL中的latest为镜像的tag，替换成相应的即可。
可以看下Header中的Docker-Content-Digest对应的正是上个Manifest List文件中amd64对应的digest，该值也正是本次请求context的sha256的校验和。
这里可以记住config下的digest，这个digest对应的正式存放镜像信息文件的sha256的校验和。

根据digest我们可以确定，在请求的URL中指明CPU的架构、OS等信息，但是仓库还是返回给了我们正确的镜像。

获取Image的配置信息

# head_accept='Accept: application/vnd.docker.distribution.manifest.v2+json'
# head_auth="Authorization: Bearer ${TOKEN}"                                           # 注意替换TOKEN的内容
# curl -i -L -H "$head_auth" -H "$head_accept" "https://registry-1.docker.io/v2/library/ubuntu/blobs/${img_digest}" 
HTTP/1.1 200 Connection Established

HTTP/1.1 307 Temporary Redirect
Content-Type: application/octet-stream
Docker-Distribution-Api-Version: registry/2.0
Location: https://production.cloudflare.docker.com/registry-v2/docker/registry/v2/blobs/sha256/77/775349758637aff77bf85e2ff0597e86e3e859183ef0baba8b3e8fc8d3cba51c/data?verify=1576077590-L0Qm7evLPvRGJXglsGLJgSjtyhQ%3D
Date: Wed, 11 Dec 2019 14:29:50 GMT
Content-Length: 0
Strict-Transport-Security: max-age=31536000

HTTP/1.1 200 Connection Established

HTTP/1.1 200 OK
Date: Wed, 11 Dec 2019 14:29:52 GMT
Content-Type: application/octet-stream
Content-Length: 3411
Connection: keep-alive
Set-Cookie: __cfduid=d378cc611e9b9c55da04c2a12a78593961576074592; expires=Fri, 10-Jan-20 14:29:52 GMT; path=/; domain=.production.cloudflare.docker.com; HttpOnly; Secure
CF-Ray: 54382738df9545a0-TPE
Accept-Ranges: bytes
Age: 1261208
Cache-Control: public, max-age=14400
ETag: "49915831e8a9bf47e493f67c9deb77d8"
Expires: Wed, 11 Dec 2019 18:29:52 GMT
Last-Modified: Thu, 31 Oct 2019 22:21:44 GMT
Vary: Accept-Encoding
CF-Cache-Status: HIT
Expect-CT: max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
x-amz-id-2: UvQpRaIldmEaUN9dgURDCf1hv9RN0YE0YXW8znQemYCLDSxURtKfIatkyLfNPV13zKh4svjHA9U=
x-amz-request-id: CD58E96DAD72CD84
x-amz-version-id: UTOzvvgdyPt7amRFsm.T0wMyWYEx0RPE
Server: cloudflare
{
    "architecture": "amd64",
    "config": {
        "ArgsEscaped": true,
        "AttachStderr": false,
        "AttachStdin": false,
        "AttachStdout": false,
        "Cmd": [
            "/bin/bash"
        ],
        "Domainname": "",
        "Entrypoint": null,
        "Env": [
            "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
        ],
        "Hostname": "",
        "Image": "sha256:f0caea6f785de71fe8c8b1b276a7094151df6058aa3f22d2902fe6b51f1a7a8f",
        "Labels": null,
        "OnBuild": null,
        "OpenStdin": false,
        "StdinOnce": false,
        "Tty": false,
        "User": "",
        "Volumes": null,
        "WorkingDir": ""
    },
    "container": "4df7a03525342ee760076ade1c80bbdd041f236654f624ca581ada54310a1574",
    "container_config": {
        "ArgsEscaped": true,
        "AttachStderr": false,
        "AttachStdin": false,
        "AttachStdout": false,
        "Cmd": [
            "/bin/sh",
            "-c",
            "#(nop) ",
            "CMD [\"/bin/bash\"]"
        ],
        "Domainname": "",
        "Entrypoint": null,
        "Env": [
            "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
        ],
        "Hostname": "4df7a0352534",
        "Image": "sha256:f0caea6f785de71fe8c8b1b276a7094151df6058aa3f22d2902fe6b51f1a7a8f",
        "Labels": {},
        "OnBuild": null,
        "OpenStdin": false,
        "StdinOnce": false,
        "Tty": false,
        "User": "",
        "Volumes": null,
        "WorkingDir": ""
    },
    "created": "2019-10-31T22:20:37.714423666Z",
    "docker_version": "18.06.1-ce",
    "history": [
        {
            "created": "2019-10-31T22:20:35.371741262Z",
            "created_by": "/bin/sh -c #(nop) ADD file:a48a5dc1b9dbfc632f6cf86fe27b770b63f07a115c98c4465dc184e303a4efa1 in / "
        },
        {
            "created": "2019-10-31T22:20:36.173590614Z",
            "created_by": "/bin/sh -c [ -z \"$(apt-get indextargets)\" ]"
        },
        {
            "created": "2019-10-31T22:20:36.882756782Z",
            "created_by": "/bin/sh -c set -xe \t\t&& echo '#!/bin/sh' > /usr/sbin/policy-rc.d \t&& echo 'exit 101' >> /usr/sbin/policy-rc.d \t&& chmod +x /usr/sbin/policy-rc.d \t\t&& dpkg-divert --local --rename --add /sbin/initctl \t&& cp -a /usr/sbin/policy-rc.d /sbin/initctl \t&& sed -i 's/^exit.*/exit 0/' /sbin/initctl \t\t&& echo 'force-unsafe-io' > /etc/dpkg/dpkg.cfg.d/docker-apt-speedup \t\t&& echo 'DPkg::Post-Invoke { \"rm -f /var/cache/apt/archives/*.deb /var/cache/apt/archives/partial/*.deb /var/cache/apt/*.bin || true\"; };' > /etc/apt/apt.conf.d/docker-clean \t&& echo 'APT::Update::Post-Invoke { \"rm -f /var/cache/apt/archives/*.deb /var/cache/apt/archives/partial/*.deb /var/cache/apt/*.bin || true\"; };' >> /etc/apt/apt.conf.d/docker-clean \t&& echo 'Dir::Cache::pkgcache \"\"; Dir::Cache::srcpkgcache \"\";' >> /etc/apt/apt.conf.d/docker-clean \t\t&& echo 'Acquire::Languages \"none\";' > /etc/apt/apt.conf.d/docker-no-languages \t\t&& echo 'Acquire::GzipIndexes \"true\"; Acquire::CompressionTypes::Order:: \"gz\";' > /etc/apt/apt.conf.d/docker-gzip-indexes \t\t&& echo 'Apt::AutoRemove::SuggestsImportant \"false\";' > /etc/apt/apt.conf.d/docker-autoremove-suggests"
        },
        {
            "created": "2019-10-31T22:20:37.550873398Z",
            "created_by": "/bin/sh -c mkdir -p /run/systemd && echo 'docker' > /run/systemd/container"
        },
        {
            "created": "2019-10-31T22:20:37.714423666Z",
            "created_by": "/bin/sh -c #(nop)  CMD [\"/bin/bash\"]",
            "empty_layer": true
        }
    ],
    "os": "linux",
    "rootfs": {
        "diff_ids": [
            "sha256:cc967c529ced563b7746b663d98248bc571afdb3c012019d7f54d6c092793b8b",
            "sha256:2c6ac8e5063e35e91ab79dfb7330c6154b82f3a7e4724fb1b4475c0a95dfdd33",
            "sha256:6c01b5a53aac53c66f02ea711295c7586061cbe083b110d54dafbeb6cf7636bf",
            "sha256:e0b3afb09dc386786d49d6443bdfb20bc74d77dcf68e152db7e5bb36b1cca638"
        ],
        "type": "layers"
    }
}

注意：为了方便观看，上方返回的json我做了格式化处理。

获取镜像层的信息

HTTP/1.1 200 Connection Established

HTTP/1.1 307 Temporary Redirect
Content-Type: application/octet-stream
Docker-Distribution-Api-Version: registry/2.0
Location: https://production.cloudflare.docker.com/registry-v2/docker/registry/v2/blobs/sha256/7d/7ddbc47eeb70dc7f08e410a6667948b87ff3883024eb41478b44ef9a81bf400c/data?verify=1576073179-ulfR1ZF4DybCnfmDhXunQSDzKN0%3D
Date: Wed, 11 Dec 2019 13:16:19 GMT
Content-Length: 0
Strict-Transport-Security: max-age=31536000

HTTP/1.1 200 Connection Established

HTTP/1.1 200 OK
Date: Wed, 11 Dec 2019 13:16:20 GMT
Content-Type: application/octet-stream
Content-Length: 26688847
Connection: keep-alive
Set-Cookie: __cfduid=d8c05cfa09534d091566b2dbc1cf57ca51576070180; expires=Fri, 10-Jan-20 13:16:20 GMT; path=/; domain=.production.cloudflare.docker.com; HttpOnly; Secure
CF-Ray: 5437bb871f2545a0-TPE
Accept-Ranges: bytes
Age: 1085759
Cache-Control: public, max-age=14400
ETag: "37579c3e2546a2e0a8e0a605d6c2feb2"
Expires: Wed, 11 Dec 2019 17:16:20 GMT
Last-Modified: Wed, 30 Oct 2019 00:25:34 GMT
Vary: Accept-Encoding
CF-Cache-Status: HIT
Expect-CT: max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
x-amz-id-2: X5lLL2k44W7TGacV5AVP3mHYcnvCU1I4WEG43mWqQVzjZPEgdmqTV2wITJU+UguBbwm+z/E6i0k=
x-amz-request-id: A4151812AF621C16
x-amz-version-id: kvJ2j8c2kVmMRGKRYdGYsqTm7J__tttP
Server: cloudflare

目录