Details
The name property is now required to create or grant an API key.

{
    "...": "...",
    "api_key": {
      "name": "key-1"
    }
}

Impact
To avoid errors, specify the name property when creating or granting API keys.

Details
We are deprecating REST API access to system indices. Most REST API requests that attempt to access system indices will return the following deprecation warning:

this request accesses system indices: [.system_index_name], but in a future
major version, direct access to system indices will be prevented by default

The following REST API endpoints access system indices as part of their implementation and will not return the deprecation warning:

Impact
To avoid deprecation warnings, do not use unsupported REST APIs to access system indices.

Details
To support future feature development, the existing MappedFieldType#fielddataBuilder method now accepts a new Supplier<SearchLookup> argument.

Impact
If you develop or maintain a mapper plugin, update your implementation of the MappedFieldType#fielddataBuilder method to accommodate the new signature.

Details
The allow_no_jobs and allow_no_datafeeds parameters in machine learning APIs are deprecated in favor of allow_no_match. The old parameters are still accepted by the APIs but a deprecation warning is emitted when the old parameter name is used in the request body or as a request parameter. High-level REST client classes now send the new allow_no_match parameter.

Impact
To avoid deprecation warnings, use the allow_no_match parameter.

Details
Index-time boosts have been deprecated since the 5.x line, but it is still possible to declare field-specific boosts in the mappings. This is now deprecated as well, and will be removed entirely in 8.0.0. Mappings containing field boosts will continue to work in 7.x but will emit a deprecation warning.

Impact
The boost setting should be removed from templates and mappings. Use boosts directly on queries instead.

Details
The {network,transport,http}.tcp.keep_idle and {network,transport,http}.tcp.keep_interval settings now have a maximum value of 300 seconds, equivalent to 5 minutes.

Impact
If specified, ensure the {network,transport,http}.tcp.keep_idle and {network,transport,http}.tcp.keep_interval settings do not exceed 300 seconds. Setting {network,transport,http}.tcp.keep_idle or {network,transport,http}.tcp.keep_interval to a value greater than 300 seconds in elasticsearch.yml will result in an error on startup.

Details
The index.max_docvalue_fields_search setting limits the number of doc value fields retrieved by a search. Previously, this setting applied only to doc value fields returned by the docvalue_fields parameter in a top-level search. The setting now also applies to doc value fields returned by an inner_hits section or top_hits aggregation.

Impact
If you use inner_hits or the top_hits aggregation, ensure index.max_docvalue_fields_search is configured correctly for your use case.

Details
The repository stats API was introduced as an experimental API in 7.8.0. The repositories metering APIs now replace the repository stats API. The repository stats API has been deprecated and will be removed in 8.0.0.

Impact
Use the repositories metering APIs. Discontinue use of the repository stats API.