push of a manifest list produces tags for image manifest by digest

[ipanova]

tagging by digest is not supported

$ http   https://pulp3-source-fedora34.fluffy.example.com/pulp/api/v3/content/container/tags/ --verify=no
HTTP/1.1 200 OK
Access-Control-Expose-Headers: Correlation-ID
Allow: GET, HEAD, OPTIONS
Connection: keep-alive
Content-Length: 1423
Content-Type: application/json
Correlation-ID: 7426be8f9c2c42c38f4ca41bf39f64f0
Date: Mon, 20 Jun 2022 11:29:16 GMT
Referrer-Policy: same-origin
Server: nginx/1.20.1
Strict-Transport-Security: max-age=15768000
Vary: Accept, Cookie
X-Content-Type-Options: nosniff
X-Frame-Options: DENY

{
    "count": 5,
    "next": null,
    "previous": null,
    "results": [
        {
            "name": "v2",
            "pulp_created": "2022-06-20T10:59:06.564946Z",
            "pulp_href": "/pulp/api/v3/content/container/tags/670ee234-dc24-4731-9811-365d7206a343/",
            "tagged_manifest": "/pulp/api/v3/content/container/manifests/3d96e778-ca70-458e-8261-2be6795ed7b8/"
        },
        {
            "name": "sha256:d8fbbbf3fec1857c32c110292a9decf9744f9f97d7247019ae4776c241395221",
            "pulp_created": "2022-06-20T10:59:05.429696Z",
            "pulp_href": "/pulp/api/v3/content/container/tags/968b2b94-fe52-4a2e-b9d5-4acdefa84f78/",
            "tagged_manifest": "/pulp/api/v3/content/container/manifests/c421e627-e4e5-435a-873a-5e2d1cf879c7/"
        },
        {
            "name": "oci",
            "pulp_created": "2022-06-20T10:57:06.625952Z",
            "pulp_href": "/pulp/api/v3/content/container/tags/9afdecec-751f-4a6c-898b-34057dc63b97/",
            "tagged_manifest": "/pulp/api/v3/content/container/manifests/8fd20736-a706-47c2-81d1-2df9e11ca8f1/"
        },
        {
            "name": "sha256:22cdd27b7173d3832d85f265a019f8a15805e7eab93479bfc76077abbd5500a6",
            "pulp_created": "2022-06-20T10:57:05.502193Z",
            "pulp_href": "/pulp/api/v3/content/container/tags/c46f10ca-0e7d-42cb-a04d-bb17ed2c8b57/",
            "tagged_manifest": "/pulp/api/v3/content/container/manifests/5da1b561-843d-4db1-8b05-2b431df145dc/"
        },
        {
            "name": "empty",
            "pulp_created": "2022-06-20T10:56:17.614301Z",
            "pulp_href": "/pulp/api/v3/content/container/tags/ea85f77a-ffd3-44a9-a9a0-3d7756fa185b/",
            "tagged_manifest": "/pulp/api/v3/content/container/manifests/f879d201-0b78-48d3-bfd6-ea2833f1a980/"
        }
    ]
}

$ podman tag  2ea2d398465f  docker.io/ipanova/image@sha256:d8fbbbf3fec1857c32c110292a9decf9744f9f97d7247019ae4776c241395221
Error: docker.io/ipanova/image@sha256:d8fbbbf3fec1857c32c110292a9decf9744f9f97d7247019ae4776c241395221: tag by digest not supported
(pulp) [vagrant@pulp3-source-fedora34 pulp_container]$ podman tag  2ea2d398465f  docker.io/ipanova/image:sha256:d8fbbbf3fec1857c32c110292a9decf9744f9f97d7247019ae4776c241395221
Error: error normalizing name "docker.io/ipanova/image:sha256:d8fbbbf3fec1857c32c110292a9decf9744f9f97d7247019ae4776c241395221": error normalizing name "docker.io/ipanova/image:sha256:d8fbbbf3fec1857c32c110292a9decf9744f9f97d7247019ae4776c241395221": invalid reference format
(pulp) [vagrant@pulp3-source-fedora34 pulp_container]$ podman tag  2ea2d398465f  docker.io/ipanova/image@sha256@d8fbbbf3fec1857c32c110292a9decf9744f9f97d7247019ae4776c241395221
Error: error normalizing name "docker.io/ipanova/image@sha256@d8fbbbf3fec1857c32c110292a9decf9744f9f97d7247019ae4776c241395221": error normalizing name "docker.io/ipanova/image@sha256@d8fbbbf3fec1857c32c110292a9decf9744f9f97d7247019ae4776c241395221": invalid reference format

[ipanova]

We might need to add validation in various places too - like sync and tagging