docs/compose/config/fields_schema_v1.json

{
  "$schema": "http://json-schema.org/draft-04/schema#",

  "type": "object",
  "id": "fields_schema_v1.json",

  "patternProperties": {
    "^[a-zA-Z0-9._-]+$": {
      "$ref": "service_schema_v1.json#/definitions/service"
    }
  },
  "additionalProperties": false
}