support --platform in oras push and oras attach

[qweeah]

What is the version of your ORAS CLI

oras v1.1.0-rc.1

What would you like to be added?

Add a new flag --platform(flag name TBD) to allow baking platform information into config data like

oras push localhost:5000/oras:v1.0.1 --artifact-type "application/vnd.example+type" --platform linux/amd64 oras--1.0.1.arm64_monterey.bottle.tar.gz
oras attach localhost:5000/oras:v1.0.1 --artifact-type "application/vnd.sbom" --platform linux/amd64 oras--1.0.1.arm64_monterey.bottle.tar.gz

The specified platform information will be stored in the config blob like https://oras.land/docs/concepts/artifact#artifacts-with-config

Why is this needed for ORAS?

User can easily build artifact with platform information without composing config blob on their own.

Are you willing to submit PRs to contribute to this feature?

• Yes, I am willing to implement it.

[amands98]

Should I include support for a platform flag ? // @qweeah

[qweeah]

@amands98 Thanks for volunteering! Please make sure the baked config is following https://github.com/opencontainers/image-spec/blob/main/config.md#properties

[shizhMSFT]

What's the media type of the config? Is it artifact-type or the standard config type? How is it supported by multiple cloud providers?

[qweeah]

Still need to apply this to oras attach

[TerryHowe]

oras atach has a platform option although I haven't tried it

[Wwwsylvia]

Still need to apply this to oras attach

Do you mean we can add a --artifact-platform flag to the manifest of the config referrers, just like we do for oras push?

oras atach has a platform option although I haven't tried it

That is to control which arch-specific manifest to attach on.

---

But what are the use cases of adding platform to a referrer?🤔

[FeynmanZhou]

Still need to apply this to oras attach

Since we lack of the scenario for oras attach, we will keep it in ORAS future milestone.

[TerryHowe]

I think a new issue for attach would make it easier

[Wwwsylvia]

I just opened a new issue for oras attach: #1537
I think we are good to close this one.