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DockerHub: sha digest doesn't match

I want to determine the sha digest for the latest docker image in DockerHub:

if I try to pull the latest image I can see the digest

# docker pull mysql:latest
...
Digest: sha256:c93ba1bafd65888947f5cd8bd45deb7b996885ec2a16c574c530c389335e9169
Status: Downloaded newer image for mysql:latest
docker.io/library/mysql:latest

so the digest is c93ba1

But if I go to https://hub.docker.com I'll see

enter image description here

So there are 2 digests: 511ca265b41c and 9a355d5c4ec0.

Also if I try to pull with any of the specified digests:

# docker pull mysql@sha256:9a355d5c4ec0351a954b11b494c597cd4e6ab2c8a04ce69c5f8332819890c43e
Error response from daemon: manifest for mysql@sha256:9a355d5c4ec0351a954b11b494c597cd4e6ab2c8a04ce69c5f8332819890c43e not found: manifest unknown: manifest unknown

# docker pull mysql@sha256:511ca265b41cabb694fda409b8ae87fb0a83db15cfb8429d581c33c7aafacddf
Error response from daemon: manifest for mysql@sha256:511ca265b41cabb694fda409b8ae87fb0a83db15cfb8429d581c33c7aafacddf not found: manifest unknown: manifest unknown

But if I try with the one that I got from the pull command it works:

docker pull mysql@sha256:c93ba1bafd65888947f5cd8bd45deb7b996885ec2a16c574c530c389335e9169
sha256:c93ba1bafd65888947f5cd8bd45deb7b996885ec2a16c574c530c389335e9169: Pulling from library/mysql
Digest: sha256:c93ba1bafd65888947f5cd8bd45deb7b996885ec2a16c574c530c389335e9169
Status: Image is up to date for mysql@sha256:c93ba1bafd65888947f5cd8bd45deb7b996885ec2a16c574c530c389335e9169
docker.io/library/mysql@sha256:c93ba1bafd65888947f5cd8bd45deb7b996885ec2a16c574c530c389335e9169

What 'm I doing wrong? And is there a way to get the digest without pulling the image?

Update: Repeated the same procedure again on MacOs using Docker Desktop 2.2

docker pull mysql:8
8: Pulling from library/mysql
...
Digest: sha256:f91e704ffa9f19b9a267d9321550a0772a1b64902226d739d3527fd6edbe3dfe
Status: Downloaded newer image for mysql:8
docker.io/library/mysql:8

Then on docker hub enter image description here

Then

docker image inspect mysql:8
[
    {
        "Id": "sha256:c8ad2be69a220e93826a6308458627b8d5624dc981050fabf950e5de5a7a08a8",
        "RepoTags": [
            "mysql:8"
        ],
        "RepoDigests": [
            "mysql@sha256:f91e704ffa9f19b9a267d9321550a0772a1b64902226d739d3527fd6edbe3dfe"
        ]

And 

docker pull mysql@sha256:a592539c5a616b6642bb48822688b6917b373a1293638f9268e8da33e5e9dd1c
sha256:a592539c5a616b6642bb48822688b6917b373a1293638f9268e8da33e5e9dd1c: Pulling from library/mysql
Digest: sha256:a592539c5a616b6642bb48822688b6917b373a1293638f9268e8da33e5e9dd1c
Status: Downloaded newer image for mysql@sha256:a592539c5a616b6642bb48822688b6917b373a1293638f9268e8da33e5e9dd1c
docker.io/library/mysql@sha256:a592539c5a616b6642bb48822688b6917b373a1293638f9268e8da33e5e9dd1c

docker pull mysql@sha256:f91e704ffa9f19b9a267d9321550a0772a1b64902226d739d3527fd6edbe3dfe
sha256:f91e704ffa9f19b9a267d9321550a0772a1b64902226d739d3527fd6edbe3dfe: Pulling from library/mysql
Digest: sha256:f91e704ffa9f19b9a267d9321550a0772a1b64902226d739d3527fd6edbe3dfe
Status: Image is up to date for mysql@sha256:f91e704ffa9f19b9a267d9321550a0772a1b64902226d739d3527fd6edbe3dfe
docker.io/library/mysql@sha256:f91e704ffa9f19b9a267d9321550a0772a1b64902226d739d3527fd6edbe3dfe

And when I do the same on Linux VM:

sudo docker pull mysql:8
8: Pulling from library/mysql
...
Digest: sha256:f91e704ffa9f19b9a267d9321550a0772a1b64902226d739d3527fd6edbe3dfe
Status: Downloaded newer image for mysql:8
docker.io/library/mysql:8

So I have no idea what is happening here

Solution

  • According to this github comment, apparently the CLI when calculating the sha256 digest uses a manifest containing all of the different machine architecture options, while each digest on the DockerHub page is calculated using a manifest with only that specific individual architecture.

    UPDATE: It's been a while since I tracked this down, so I don't remember the details, but for more info check out this page. I believe it has to do with the difference between the sha for an image manifest, and the sha for the manifest list...