skopeo inspect docker://reg.docker.alibaba-inc.com/ray_deploy/alios7u2-min:1.0_nydus_v2

    1. {
    2.     "Name": "reg.docker.alibaba-inc.com/ray_deploy/alios7u2-min",
    3.     "Digest": "sha256:ce4ddaa7db3e7f1aebde0c91b0d74d096a6777fd1a6af6b4094e6148fda6187d",
    4.     "RepoTags": [
    5.         "1.0",
    6.         "1.0_nydus_v2"
    7.     ],
    8.     "Created": "2021-02-04T07:19:11.851931645Z",
    9.     "DockerVersion": "",
    10.     "Labels": null,
    11.     "Architecture": "amd64",
    12.     "Os": "linux",
    13.     "Layers": [
    14.         // compressed-diff-digest
    15.         "sha256:58f95076ebeba2a79f6b786ec216b51c74a6d3ead24c2537ce0f84ae974803c7"
    16.     ],
    17.     "Env": [
    18.         "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
    19.         "container=docker"
    20.     ]
    21. }

    skopeo inspect —config docker://reg.docker.alibaba-inc.com/ray_deploy/alios7u2-min:1.0_nydus_v2

    1. {
    2.     "created": "2021-02-04T07:19:11.851931645Z",
    3.     "architecture": "amd64",
    4.     "os": "linux",
    5.     "config": {
    6.         "Env": [
    7.             "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
    8.             "container=docker"
    9.         ],
    10.         "Cmd": [
    11.             "/sbin/init"
    12.         ]
    13.     },
    14.     "rootfs": {
    15.         "type": "layers",
    16.         "diff_ids": [
    17.         //非压缩的diff-digest，overlay-layers下的目录         
    18.           "sha256:64ab458946b28f56485b972e599da73f5a7b176ecdf050bb5740c6638c959325"
    19.         ]
    20.     }
    21. }

    overlay-images/${imageId}/manifest 存储了该镜像所有layer的 非压缩sha256 和layer大小。

    overlay-layers/layers.json 存储了所有layer的 非压缩sha256 、压缩sha256、layer id等信息。layer id就是放在overlay-layers目录下的layer文件名。

    images recorded in a registry should be compressed，and ordinarily the compression is accompanied with an update to the MIME type。在本地build镜像时，在本地存储的可能是未压缩的layer文件，它的media type是没有gzip。在docker registry中存储的layer都是压缩过的，压缩完成之后会同时修改media type。上传的layer理论上不应该出现未压缩的layer。

    1. [{
    2.     "id": "2d065512630f97ed1172a4de9e654bff7fff0ed2839eec730936ffa21667d048",
    3.     "parent": "81ef8397e6bc354f1ad2a223198cc56973de6c1409aa4e31bfe90fd7064037c3",
    4.     "created": "2021-08-19T02:53:31.854085322Z",
    5.     "compressed-diff-digest": "sha256:afa1907fa2c432a560d72538932a583f39d83efc22874b93996437a986e3bef3",
    6.     "compressed-size": 767,
    7.     "diff-digest": "sha256:b62b08bf1f2c95a698f60294b87558ed4b700e8e0a0eac037623f986d55d9278",
    8.     "diff-size": 4096,
    9.     "compression": 2,
    10.     "uidset": [
    11.       0
    12.     ],
    13.     "gidset": [
    14.       0
    15.     ]
    16.   },
    17.  {
    18.   "id": "a3e9bebf7bd6361b1dd92ecf6f2b77c0ece19a4ddcb73198df0a97f1a1af7578",
    19.   "parent": "ed42d543fba087bf0262c7c2c0a37d2ced7d6410afcf9e43ed648904b9e4c94e",
    20.   "created": "2021-08-19T02:53:41.907387302Z",
    21.   "compressed-diff-digest": "sha256:5105d5ae3df1768750d351f890511fe751dea205b6e89a6d0cacd0efd8a08b2f",
    22.   "compressed-size": 75776,
    23.   "diff-digest": "sha256:5105d5ae3df1768750d351f890511fe751dea205b6e89a6d0cacd0efd8a08b2f",
    24.   "diff-size": 75776,
    25.   "uidset": [
    26.     0
    27.   ],
    28.   "gidset": [
    29.     0
    30.   ]
    31. },
    32. {
    33.   "id": "fb0a6af74b7c351d8a960405076ce6001f427b9081f38b932f575b041abd89c4",
    34.   "parent": "bf2f9f80a90ab5a5a78ee6a4486498f383c5438a6c85e69784d1b5aa526506bc",
    35.   "created": "2021-08-19T02:53:35.899785835Z",
    36.   "compressed-diff-digest": "sha256:5f70bf18a086007016e948b04aed3b82103a36bea41755b6cddfaf10ace3c6ef",
    37.   "compressed-size": 1024,
    38.   "diff-digest": "sha256:5f70bf18a086007016e948b04aed3b82103a36bea41755b6cddfaf10ace3c6ef",
    39.   "diff-size": 1024
    40. }]