Publish the canonical features list, or at least otherwise formalise how downstream repositories are to obtain it at a specific version

[QuintinWillison]

Blocked by ably/ably-common#70.

Will then enable us to consume this package in SDK repository CI workflows, and elsewhere, to validate and render manifests.

┆Issue is synchronized with this Jira Uncategorised by Unito

[QuintinWillison]

I had a call with @owenpearson this afternoon where we discussed this.

While we were in agreement that Node.js is probably a sensible runtime to use for manifest processing, including validation against the canonical features list, Owen made the point that npm is probably not needed or desirable to use for distributing the canonical features list. There is no reason why we can't simply use GitHub's raw URLs... i.e. what we get when clicking the Raw button when inspecting sdk.yaml in the sdk-features branch (while ably/ably-common#142 is open):

% curl -I https://github.com/ably/ably-common/raw/sdk-features/features/sdk.yaml
HTTP/2 302
server: GitHub.com
date: Mon, 13 Jun 2022 13:49:06 GMT
content-type: text/html; charset=utf-8
location: https://raw.githubusercontent.com/ably/ably-common/sdk-features/features/sdk.yaml
content-length: 0

% curl -I https://raw.githubusercontent.com/ably/ably-common/sdk-features/features/sdk.yaml
HTTP/2 200
cache-control: max-age=300
content-type: text/plain; charset=utf-8
date: Mon, 13 Jun 2022 13:49:18 GMT
content-length: 15594

(some headers removed from above snippet for brevity)

I've checked and sdk-features can be replaced with a Git tag - the version of ably-common.

Simple enough to fetch at runtime, in tool(s) run in CI or during local development.

[lmars]

Did you consider uploading to sdk.ably.com as the canonical source?

[QuintinWillison]

We did - perhaps by expanding the existing folder structure. I forgot exactly why @owenpearson and I dismissed it but I think it was simply because it was an additional moving part that wasn't strictly necessary - may as well "go direct to the source", as it were.

[lmars]

Ok fair enough 👍