Archived settingsedit

Elasticsearch typically removes support for deprecated settings at major version releases. If you upgrade a cluster with a deprecated persistent cluster setting to a version that no longer supports the setting, Elasticsearch automatically archives that setting. Similarly, if you upgrade a cluster that contains an index with an unsupported index setting, Elasticsearch archives the index setting.

Archived settings start with the archived. prefix and are ignored by Elasticsearch.

Archived cluster settingsedit

After an upgrade, you can view archived cluster settings using the cluster get settings API.

GET _cluster/settings?flat_settings=true&filter_path=persistent.archived*

You can remove archived cluster settings using the cluster update settings API.

PUT _cluster/settings
{
  "persistent": {
    "archived.*": null
  }
}

Elasticsearch doesn’t archive transient cluster settings or settings in elasticsearch.yml. If a node includes an unsupported setting in elasticsearch.yml, it will return an error at startup.

Archived index settingsedit

Before you upgrade, remove any unsupported index settings from index and component templates. Elasticsearch doesn’t archive unsupported index settings in templates during an upgrade. Attempts to use a template that contains an unsupported index setting will fail and return an error. This includes automated operations, such the ILM rollover action.

You can view archived settings for an index using the get index settings API.

GET my-index/_settings?flat_settings=true&filter_path=**.settings.archived*

Removing archived index settings requires a reindex after the upgrade. However, reindexing can be resource intensive. Because Elasticsearch ignores archived settings, you can safely leave them in place if wanted.

POST _reindex
{
  "source": {
    "index": "my-index"
  },
  "dest": {
    "index": "reindexed-v8-my-index"
  }
}