Is that possible to get image ID from Docker Registry V2?

问题:

When an image has been pushed to registry V2, does the image ID will be pushed to registry as well? Is that possible to get image ID for a certain repository from V2 registry?

回答1:

If the image was pushed with Docker Client 1.10 or above, you can obtain the image ID from the registry with

GET /v2/<image>/manifests/<tag>  

Your request must include the header

Accept: application/vnd.docker.distribution.manifest.v2+json 

In the response, the image ID will be in the Content-Docker-Digest Response header.

回答2:

From my research, you can obtain the image ID from the registry(2.3.0+) with

curl -H 'Accept: application/vnd.docker.distribution.manifest.v2+json' http://$server/v2/$repo/manifests/$tag

and the config.digest field in the response represents imageID,that what you want!

for example

refers: https://duyanghao.github.io/docker-registry-pull-manifest-v2/

回答3:

As best I can tell, they are not stored in any api accessible location:

bash$ docker run -d -p 5000:5000 --restart=always --name registry registry:2 Unable to find image 'registry:2' locally 2: Pulling from library/registry ... bash$ docker tag busybox localhost:5000/busybox bash$ docker push localhost:5000/busybox The push refers to a repository [localhost:5000/busybox] 5f70bf18a086: Pushed  ... bash$ curl http://localhost:5000/v2/busybox/tags/list {"name":"busybox","tags":["latest"]} bash$ curl http://localhost:5000/v2/busybox/manifests/latest {    "schemaVersion": 1,    "name": "busybox",    "tag": "latest",    "architecture": "amd64",    "fsLayers": [       {          "blobSum": "sha256:a3ed95caeb02ffe68cdd9fd84406680ae93d633cb16422d00e8a7c22955b46d4"       },       {          "blobSum": "sha256:385e281300cc6d88bdd155e0931fbdfbb1801c2b0265340a40481ee2b733ae66"       }    ],    "history": [       {          "v1Compatibility": "{\"architecture\":\"amd64\",\"config\":{\"Hostname\":\"156e10b83429\",\"Domainname\":\"\",\"User\":\"\",\"AttachStdin\":false,\"AttachStdout\":false,\"AttachStderr\":false,\"Tty\":false,\"OpenStdin\":false,\"StdinOnce\":false,\"Env\":null,\"Cmd\":[\"sh\"],\"Image\":\"56ed16bd6310cca65920c653a9bb22de6b235990dcaa1742ff839867aed730e5\",\"Volumes\":null,\"WorkingDir\":\"\",\"Entrypoint\":null,\"OnBuild\":null,\"Labels\":{}},\"container\":\"5f8098ec29947b5bea80483cd3275008911ce87438fed628e34ec0c522665510\",\"container_config\":{\"Hostname\":\"156e10b83429\",\"Domainname\":\"\",\"User\":\"\",\"AttachStdin\":false,\"AttachStdout\":false,\"AttachStderr\":false,\"Tty\":false,\"OpenStdin\":false,\"StdinOnce\":false,\"Env\":null,\"Cmd\":[\"/bin/sh\",\"-c\",\"#(nop) CMD [\\\"sh\\\"]\"],\"Image\":\"56ed16bd6310cca65920c653a9bb22de6b235990dcaa1742ff839867aed730e5\",\"Volumes\":null,\"WorkingDir\":\"\",\"Entrypoint\":null,\"OnBuild\":null,\"Labels\":{}},\"created\":\"2016-03-18T18:22:48.810791943Z\",\"docker_version\":\"1.9.1\",\"id\":\"437595becdebaaaf3a4fc3db02c59a980f955dee825c153308c670610bb694e1\",\"os\":\"linux\",\"parent\":\"920777304d1d5e337bc59877253e946f224df5aae64c72538672eb74637b3c9e\"}"       },       {          "v1Compatibility": "{\"id\":\"920777304d1d5e337bc59877253e946f224df5aae64c72538672eb74637b3c9e\",\"created\":\"2016-03-18T18:22:48.262403239Z\",\"container_config\":{\"Cmd\":[\"/bin/sh -c #(nop) ADD file:47ca6e777c36a4cfffe3f918b64a445c8f32300deeb9dfa5cc47261bd7b75d21 in /\"]}}"       }    ],    "signatures": [       {          "header": {             "jwk": {                "crv": "P-256",                "kid": "FIFX:SJRD:AQHW:MCFX:M6WC:LXI2:3VO2:4LFW:UHDZ:QUN7:OLX4:6WGD",                "kty": "EC",                "x": "Xm8wJTzw3nb--rGoD3dxjKffikj7Snb9dHW-qGbqSAM",                "y": "GnATS--7lVcA_-jQGuDKTtjhmnGgvBrx8rLdlPOJV3U"             },             "alg": "ES256"          },          "signature": "f8NVzOF6ujm_0COedniGCGL_q3KsTfKFM9T8ZZDf2MSIMJ3TYoR_s795NqdEy8yWaoLuT2LoI0BCEsuOTZUhCw",          "protected": "eyJmb3JtYXRMZW5ndGgiOjE5MTQsImZvcm1hdFRhaWwiOiJDbjAiLCJ0aW1lIjoiMjAxNi0wNi0xMVQwMToxMzoyMVoifQ"       }    ] bash$ curl -I http://localhost:5000/v2/busybox/manifests/latest HTTP/1.1 200 OK Content-Length: 2561 Content-Type: application/vnd.docker.distribution.manifest.v1+prettyjws Docker-Content-Digest: sha256:e45f25b1760f616e65f106b424f4ef29185fbd80822255d79dabc73b8eb715ad Docker-Distribution-Api-Version: registry/2.0 Etag: "sha256:e45f25b1760f616e65f106b424f4ef29185fbd80822255d79dabc73b8eb715ad" X-Content-Type-Options: nosniff Date: Sat, 11 Jun 2016 01:21:26 GMT 

No where in any of those API calls could I find the desired 47bcc53... image id that I see locally.

bash$ docker inspect busybox:latest [     {         "Id": "sha256:47bcc53f74dc94b1920f0b34f6036096526296767650f223433fe65c35f149eb",         "RepoTags": [             "busybox:latest",             "localhost:5000/busybox:latest"         ],         "RepoDigests": [],         "Parent": "",         "Comment": "",         "Created": "2016-03-18T18:22:48.810791943Z",         "Container": "5f8098ec29947b5bea80483cd3275008911ce87438fed628e34ec0c522665510",         "ContainerConfig": {             "Hostname": "156e10b83429",             "Domainname": "",             "User": "",             "AttachStdin": false,             "AttachStdout": false,             "AttachStderr": false,             "Tty": false,             "OpenStdin": false,             "StdinOnce": false,             "Env": null,             "Cmd": [                 "/bin/sh",                 "-c",                 "#(nop) CMD [\"sh\"]"             ],             "Image": "56ed16bd6310cca65920c653a9bb22de6b235990dcaa1742ff839867aed730e5",             "Volumes": null,             "WorkingDir": "",             "Entrypoint": null,             "OnBuild": null,             "Labels": {}         },         "DockerVersion": "1.9.1",         "Author": "",         "Config": {             "Hostname": "156e10b83429",             "Domainname": "",             "User": "",             "AttachStdin": false,             "AttachStdout": false,             "AttachStderr": false,             "Tty": false,             "OpenStdin": false,             "StdinOnce": false,             "Env": null,             "Cmd": [                 "sh"             ],             "Image": "56ed16bd6310cca65920c653a9bb22de6b235990dcaa1742ff839867aed730e5",             "Volumes": null,             "WorkingDir": "",             "Entrypoint": null,             "OnBuild": null,             "Labels": {}         },         "Architecture": "amd64",         "Os": "linux",         "Size": 1112820,         "VirtualSize": 1112820,         "GraphDriver": {             "Name": "aufs",             "Data": null         },         "RootFS": {             "Type": "layers",             "Layers": [                 "sha256:1834950e52ce4d5a88a1bbd131c537f4d0e56d10ff0dd69e66be3b7dfa9df7e6",                 "sha256:5f70bf18a086007016e948b04aed3b82103a36bea41755b6cddfaf10ace3c6ef"             ]         }     } ] 

From this image spec the image id is a reproducible hash, and I do see the same value for the image id on different systems.

ImageID Each image's ID is given by the SHA256 hash of its configuration JSON. It is represented as a hexadecimal encoding of 256 bits, e.g., sha256:a9561eb1b190625c9adb5a9513e72c4dedafc1cb2d4c5236c9a6957ec7dfd5a9. Since the configuration JSON that gets hashed references hashes of each layer in the image, this formulation of the ImageID makes images content-addresable.

So if you can reproduce the configuration JSON from the API calls, then you may be able to generate the image id yourself.

文章来源: Is that possible to get image ID from Docker Registry V2?