基于https实现镜像所有相关元信息的获取
在弱网环境下，下载镜像很慢且容易出错，基于这个原因需要开发更加可靠且支持断点续传的镜像下载程序
由于Docker Hub在国内无法访问，用自己的阿里云镜像加速替代来进行测试
下面以下载linux/amd64的ubuntu22.04镜像为例
Authentication
例中的阿里云镜像加速无需校验，如果镜像源需要校验，那么首先获取token，然后加入header
-H "Authorization: Bearer <Token>"
获取Manifest
curl -H "Accept: application/vnd.oci.image.index.v1+json" \
-H "Accept: application/vnd.oci.image.manifest.v1+json" \
-H "Accept: application/vnd.docker.distribution.manifest.v2+json" \
-H "Accept: application/vnd.docker.distribution.manifest.list.v2+json" \
-s https://no8ju4hi.mirror.aliyuncs.com/v2/library/ubuntu/manifests/22.04
对于多个架构的镜像仓库，会获取到所有架构的Digest[1]
ubuntu:22.04->Manifests
{
"manifests": [
{
"digest": "sha256:3c3de9608507804525ff4303874525760ea36d62606e8105f515adaa761b80cb",
"mediaType": "application/vnd.docker.distribution.manifest.v2+json",
"platform": {
"architecture": "amd64",
"os": "linux"
},
"size": 529
},
{
"digest": "sha256:77e15e9408b4057b6cb6b66fb004a488d42496b60d2fdc02ac73c38e3206d886",
"mediaType": "application/vnd.docker.distribution.manifest.v2+json",
"platform": {
"architecture": "arm",
"os": "linux",
"variant": "v7"
},
"size": 529
},
{
"digest": "sha256:c0c089b5b5b1ea9e860a12a35042d832dcb1733f69fe57089b3152577d96ea35",
"mediaType": "application/vnd.docker.distribution.manifest.v2+json",
"platform": {
"architecture": "arm64",
"os": "linux",
"variant": "v8"
},
"size": 529
},
{
"digest": "sha256:b49ca9c2c0555ed157127cd429996e11900085b8b982414cc48483a1ca5c046b",
"mediaType": "application/vnd.docker.distribution.manifest.v2+json",
"platform": {
"architecture": "ppc64le",
"os": "linux"
},
"size": 529
},
{
"digest": "sha256:dce81b3b890c5f5637821a97f45ea9d42dda08c06a3069ae9559ce32385af4e0",
"mediaType": "application/vnd.docker.distribution.manifest.v2+json",
"platform": {
"architecture": "riscv64",
"os": "linux"
},
"size": 529
},
{
"digest": "sha256:e45f2138cf3a542f701097c780c96a4a7b8a77d76e27f9ffc1986fda63debd43",
"mediaType": "application/vnd.docker.distribution.manifest.v2+json",
"platform": {
"architecture": "s390x",
"os": "linux"
},
"size": 529
}
],
"mediaType": "application/vnd.docker.distribution.manifest.list.v2+json",
"schemaVersion": 2
}
根据上面得到的Manifest，可以获取linux/amd64的镜像对应的信息
- digest: "sha256:3c3de9608507804525ff4303874525760ea36d62606e8105f515adaa761b80cb"
- architecture : "amd64"
- os : "linux"
- size : 424
curl -H "Accept: application/vnd.oci.image.index.v1+json" \
-H "Accept: application/vnd.oci.image.manifest.v1+json" \
-H "Accept: application/vnd.docker.distribution.manifest.v2+json" \
-H "Accept: application/vnd.docker.distribution.manifest.list.v2+json" \
-s https://no8ju4hi.mirror.aliyuncs.com/v2/library/ubuntu/manifests/sha256:3c3de9608507804525ff4303874525760ea36d62606e8105f515adaa761b80cb
对于只有一个架构的镜像，执行第一段命令行，会跳过步骤[1]，直接得到下面的结果
ubuntu:22.04->sha256:3c3de9608507804525ff4303874525760ea36d62606e8105f515adaa761b80cb
{
"schemaVersion": 2,
"mediaType": "application/vnd.docker.distribution.manifest.v2+json",
"config": {
"mediaType": "application/vnd.docker.container.image.v1+json",
"size": 1462,
"digest": "sha256:9d28ccdc1fc782ec635c98e55ff68b05e6de1df2c7fcbbb4385f023368eec716"
},
"layers": [
{
"mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
"size": 29886454,
"digest": "sha256:aee1767db0dd7da5c30ffaef2282976fe8730cdb0a7b1ecda17cd3c85374fa57"
}
]
}
获取Metadata
根据上面的Manifest，可以得到镜像信息文件的路径
另外可以知道文件的sha256值为9d28ccdc1fc782ec635c98e55ff68b05e6de1df2c7fcbbb4385f023368eec716，大小为1462
wget https://no8ju4hi.mirror.aliyuncs.com/v2/library/ubuntu/blobs/sha256:9d28ccdc1fc782ec635c98e55ff68b05e6de1df2c7fcbbb4385f023368eec716
linux/amd64 ubuntu:22.04镜像信息
{
"architecture": "amd64",
"config": {
"Hostname": "",
"Domainname": "",
"User": "",
"AttachStdin": false,
"AttachStdout": false,
"AttachStderr": false,
"Tty": false,
"OpenStdin": false,
"StdinOnce": false,
"Env": [
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
],
"Cmd": [
"bash"
],
"Image": "sha256:c0ffde4acd3f60443d26c66a72e3f18f9da32f570a45ab54ef0d56a301a50150",
"Volumes": null,
"WorkingDir": "",
"Entrypoint": null,
"OnBuild": null,
"Labels": null
},
"container": "a2b4f5c93fe1e35e98c8624c70be1f9f61147f6568992d1036640ed69e40de6c",
"container_config": {
"Hostname": "a2b4f5c93fe1",
"Domainname": "",
"User": "",
"AttachStdin": false,
"AttachStdout": false,
"AttachStderr": false,
"Tty": false,
"OpenStdin": false,
"StdinOnce": false,
"Env": [
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
],
"Cmd": [
"/bin/sh",
"-c",
"#(nop) ",
"CMD [\"bash\"]"
],
"Image": "sha256:c0ffde4acd3f60443d26c66a72e3f18f9da32f570a45ab54ef0d56a301a50150",
"Volumes": null,
"WorkingDir": "",
"Entrypoint": null,
"OnBuild": null,
"Labels": {}
},
"created": "2021-12-04T02:21:12.903923136Z",
"docker_version": "20.10.7",
"history": [
{
"created": "2021-12-04T02:21:12.507294562Z",
"created_by": "/bin/sh -c #(nop) ADD file:1e60bfbe5a32672bfcd507fc81d927e28eb8b8b12907819058ba9bed8d6b8ac1 in / "
},
{
"created": "2021-12-04T02:21:12.903923136Z",
"created_by": "/bin/sh -c #(nop) CMD [\"bash\"]",
"empty_layer": true
}
],
"os": "linux",
"rootfs": {
"type": "layers",
"diff_ids": [
"sha256:950d1cd211572857ec798f05767ad7614025ec505d4e85df9d5e62662ed4fea9"
]
}
}
下载镜像的所有blob
根据Manifest，可以知道当前镜像只有一个Layer，其对应的blob为sha256:aee1767db0dd7da5c30ffaef2282976fe8730cdb0a7b1ecda17cd3c85374fa57，大小为29886454
下载对应blob
wget https://no8ju4hi.mirror.aliyuncs.com/v2/library/ubuntu/blobs/sha256:aee1767db0dd7da5c30ffaef2282976fe8730cdb0a7b1ecda17cd3c85374fa57
元信息校验
所有的元信息都有sha256和size两个参数，当下载完成时，可以比较文件大小和sha256sum值，完全一致则下载的文件无误，否则需要重新下载
标签：存储,vnd,可控,v2,application,json,镜像,docker,sha256 From： https://www.cnblogs.com/umichan0621/p/18009675