Support $schema reference to JSON schema

[aaron-meyers]

Currently JSON schema for a YAML file must be specified externally, either via settings or from the public schema store.

I'd like to be able to specify the schema to use in the YAML document itself. This is possible with JSON documents by specifying a $schema property, e.g.

{
  "$schema": "http://some.org/schema",
  "prop1": "value1"
  ...
}

It seems reasonable to me that the same convention could be supported for YAML documents (as this is defined as part of the JSON schema spec itself):

$schema: http://some.org/schema
prop1: value1
...

[pappasam]

This feature would be incredible.

[apupier]

I don't think that we can use the notation

$schema: http://some.org/schema
prop1: value1

because it means that the $schema should be part of the schema definition. It seems quite intrusive. All schemas would need to be updated.

What about using a comment/modeline? such as:

# json-schema: http://some.org/schema
prop1: value1

or

# yaml-language-server: json-schema=http://some.org/schema
prop1: value1

or

# yaml-language-server: $schema=http://some.org/schema
prop1: value1

nota: would be best to have it part of the specification but it doesn't seem to be part of priorities: json-schema-org/json-schema-spec#828

[ssbarnea]

Lets open a sister ticket on YAML meta repository itself, maybe YAML spec authors can help us make a good/future proof decision?

[apupier]

YAML meta repository itself

Can you precise which repository it is please?

[ssbarnea]

I think there is an existing ticket at yaml/yaml-spec#33 -- better to comment on it. Also a good channel to engage with spec people is #yaml-dev on freenode. Maybe there is some hope...

[apupier]

I tried to put a not yet defined directive and unfortunately, they are not ignored. It is reporting a validation error. I think that we can go with a comment # something as a first iteration, waiting that Yaml spec introduce the specific Yaml schema directive.
When the yaml schema directive will be available, it will be relatively simple to support it also.

[apupier]

implemented using # yaml-language-server: $schema=http://some.org/schema format