Add filtering for default index settings

[nikita-sheremet-java-developer]

Here is example about retriving filtered settings for index:

GET /log_2013_-*/_settings/index.number_*

With include_defaults it can return also default settings:

GET /log_2013_-*/_settings/index.number_*?include_defaults=true

But when it comes to filter default values, for exmaple index.blocks.write it returns empty responce:

GET /log_2013_-*/_settings/index.blocks.write*?include_defaults=true

Because index.blocks.write is placed in to "defaults" sectionm like that:

    {
      "settings": {
        "index": {
          "creation_date": "1527152951908",
          "number_of_shards": "5",
          "number_of_replicas": "1",
          "uuid": "_hzrBivpTZqYcZOwi-7P3g",
          "version": {
            "created": "6020099"
          },
          "provided_name": "some-7d0b0bce-de81-439a-a5de-bcdb8aaef3eb"
        }
      },
      "defaults": {
        "index": {
          ...
          "blocks": {
            "metadata": "false",
            "read": "false",
            "read_only_allow_delete": "false",
            "read_only": "false",
            "write": "false"
          },
          "max_script_fields": "32",
          ...
        }
      }
    }

[elasticmachine]

Pinging @elastic/es-core-infra

[javanna]

@nikita-sheremet-java-developer which version are you on? Next time could you please include the info requested in the issue template rather than overriding it as a whole? Thank you!

I did some digging on this. Filtering of default values was recently fixed, see #29539 and #29229. Filters were previously not applied to the default settings. That lead to getting an empty response whenever a setting was not listed in the "default" section, although there would be matches in the default section. The following works now on master and 6.x (fix is due to be released with 6.4.0):

curl 'localhost:9200/_settings/index.blocks.write?include_defaults=true&pretty'
{
  "index" : {
    "settings" : { },
    "defaults" : {
      "index" : {
        "blocks" : {
          "write" : "false"
        }
      }
    }
  }
}

[nikita-sheremet-java-developer]

My version is 6.2, sorry.

Thanks you for reply.