Clarification on org.opencontainers.image.created annotation

[ayashjorden]

Hello,
When calling oras push, it automatically adds the org.opencontainers.image.created:ISO_8601 annotation on the result manifest.
This is causing a behavior such that pushing the same file, config, and tag multiple times, results in one tag, but multiple manifests.

EDIT: The file we push is not a container image component, but rather a plain tarball that we need to host at scale.

For example:

oras push \
  -v -d \
  -H "Authorization: Bearer $TOKEN" \
  -H "Accept: application/prs.foo.bar.v1+json" \
  localhost:3009/$REPO:v2 \
  --config ./path/to/config.json:application/prs.foo.bar.config.v1+json \
  ./path/tofakepayload.tar.gz:application/prs.vmw.foo.bar.archive.v1+tar+gzip

Invoking the above command, will result in 3 manifests, each id identical, except the org.opencontainers.image.created annotation has different values.
Also, not sure how to set the manifest own media-type to our custom type.

{
  "annotations": {
    "org.opencontainers.image.created": "2023-08-17T18:52:44Z" <==== this value gets updated every oras push
  },
  "config": {
    "mediaType": "application/prs.foo.bar.config.v1+json",
    "digest": "sha256:2fa506d81279afb5ab77906abd91bcdf7961da1840",
    "size": 206,
    "urls": null,
    "annotations": null
  },
  "layers": [
    {
      "mediaType": "application/prs.vmw.foo.bar.archive.v1+tar+gzip",
      "digest": "sha256:4ac5b7fc9c815e11f9fa4e0fb84807b0c3b5",
      "size": 358,
      "urls": null,
      "annotations": {
        "org.opencontainers.image.title": "test/unit/routes/fakepayload.tar.gz"
      }
    }
  ],
  "mediaType": "application/vnd.oci.image.manifest.v1+json"
}

1. Is the above usage correct and the modified values of org.opencontainers.image.created expected?
2. I'd expect that repetitive identical oras push would result in the same manifest/tag so only the first one would create the resources, but further calls would just get 200OK for the HEAD calls.

• The updated value in the annotation causing the manifest checksum to change.

Happy to add more info as required,
Jordan