Add JSON schema for shard.yml

[nobodywasishere]

Implements #622. I can add automated tests if desired. After this, I can add it to JSON Schema Store.

I wasn't sure if we should restrict additional properties in the file, as there may be other tools that add stuff to the shard.yml. Off the top of my head, I can't remember any though, and they should probably move those kinds of things to their own config file.

Also if you're using VSCode, you can add this to the .vscode/settings.json and it will use the schema to vaidate the shard.yml that shards uses. I used this for testing.

// .vscode/settings.json
{
  "yaml.schemas": {
    "docs/shard.yml.schema.json": "shard.yml"
  }
}

[ysbaddaden]

Nice work.

It would be nice to see how it behaves with existing shard.yml files, for large public projects (e.g. lucky), and if it catches some errors.

[nobodywasishere]

Here are some examples of it with existing shard.ymls

Lucky:

Amber:

Mint:

Blurhash.cr:

[nobodywasishere]

Here are some of the errors it catches, alongside general format/form errors:

It currently doesn't verify dependency version: tags, the crystal: version tag, or the github/gitlab/bitbucket user/repo format

[straight-shoota]

LGTM 👍

[nobodywasishere]

Is there anything else that needs to be done for this?

[ysbaddaden]

thought (non blocking): I'm wondering if we could host a HTML rendering of the shard.yml spec at a stable place under https://crystal-lang.org and link to that page instead of a github file that may be moved 🤔

poke @straight-shoota

[straight-shoota]

Good point, we should certainly do that. Would fit right next to https://crystal-lang.org/reference/1.11/man/shards
Not sure why we're missing it there 🤔
Anyway, we can merge this as is and update the URL later.

[straight-shoota]

Ah, seems like I had this idea a long time ago already: crystal-lang/crystal-book#476
But we haven't managed to make the format compatible with HTML rendering: #488

[nobodywasishere]

SchemaStore/schemastore#3669