feat: add support for arbitrary metadata

[eduardoboucas]

Adds support for arbitrary metadata, supplied by users, to be stored alongside entries.

To write an entry with metadata, one can supply the metadata option to the set() method:

const store = getStore("my-store")

await store.set("some-key", "some-value", { metadata: { name: "Netlify", cool: true } })

To read an entry and also retrieve its metadata, a new getWithMetadata() method has been added:

const store = getStore("my-store")
const { data, etag, metadata } = await store.getWithMetadata("some-key")

assert.equal(await data.text(), "some-value")
assert.equal(typeof etag, "string")
assert.deepEqual(metadata, { name: "Netlify", cool: true })

Needs https://github.com/netlify/netlify-server/pull/3111.

Part of https://github.com/netlify/pillar-runtime/issues/751.

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[eduardoboucas]

Methods on this file haven't changed. They were just moved from store.ts.

This happened in its own commit, so reviewing each commit individually might help.

[charliegroll]

what happens if that parsing fails? do we just bubble up the SyntaxError? would it make sense to include a note about what happens?

[eduardoboucas]

Yes, the same error that you get when parsing an invalid Response will be thrown. I can add a note to the docs.

[charliegroll]

should we reference the Metadata type in the return type?

[ascorbic]

I reckon it's ok in the docs to just say object. It's just Record<string, unknown>

[eduardoboucas]

Yeah, I don't think there's much value in using the custom type here.

[ascorbic]

Looks good. Do you think it would be possible to also implement getMetadata, which uses a HEAD request and returns just the metadata?

[eduardoboucas]

Looks good. Do you think it would be possible to also implement getMetadata, which uses a HEAD request and returns just the metadata?

I think so, although maybe not for the beta since it'll require some work in nfserver.

[ascorbic]

It could be a nice addition at some point, to cheaply check metadata before requesting potentially large objects