`service.node.role` should be `service.node.roles` and support multiple keywords

I’m working on adding a node.roles configuration to Kibana, and discovered some discrepancies in the spec that was merged in https://github.com/elastic/ecs/pull/1916 and the use case we had envisioned for this in Kibana.

In our configuration, we want to allow nodes to have multiple roles. So for example, the following would be a valid value for the field:

node.roles: ['ui', 'background-tasks']

The PR that was merged only allows for a single item (not normalized as an array) and is also named service.node.role (singular).

Looking for advice on what to do here, since this was merged for 8.3. It is almost certainly too late to do anything about it, but unfortunately it means we won’t be able to adhere to this spec in Kibana based on the technical needs of our project.

Should we leave the field as-is and just not use it? Deprecate it? Something else?

FWIW, we won’t be actually introducing usage of this field in Kibana until at least 8.4.

cc @kobelb @matschaffer @ebeahan

[kgeller]

@lukeelmers @matschaffer After some discussion with the team this morning, we think that the path forward should be: 1) release 8.3 with node.role expecting a single value, 2) immediately deprecate that field for 8.3.1, and 3) add node.roles expecting the array for 8.4.

We are also going to add in a note into the 8.3 ECS release notes about expecting that field to be corrected.

Does this sound good to you both?

[kgeller]

Deprecation notice and new field have been added.