Cluster Update Settings

Allows to update cluster wide specific settings. Settings updated can either be persistent (applied across restarts) or transient (will not survive a full cluster restart). Here is an example:

PUT /_cluster/settings
{
    "persistent" : {
        "indices.recovery.max_bytes_per_sec" : "50mb"
    }
}

Or:

PUT /_cluster/settings?flat_settings=true
{
    "transient" : {
        "indices.recovery.max_bytes_per_sec" : "20mb"
    }
}

The cluster responds with the settings updated. So the response for the last example will be:

{
    ...
    "persistent" : { },
    "transient" : {
        "indices.recovery.max_bytes_per_sec" : "20mb"
    }
}

Resetting persistent or transient settings can be done by assigning a null value. If a transient setting is reset, the persistent setting is applied if available. Otherwise Elasticsearch will fallback to the setting defined at the configuration file or, if not existent, to the default value. Here is an example:

PUT /_cluster/settings
{
    "transient" : {
        "indices.recovery.max_bytes_per_sec" : null
    }
}

Reset settings will not be included in the cluster response. So the response for the last example will be:

{
    ...
    "persistent" : {},
    "transient" : {}
}

Settings can also be reset using simple wildcards. For instance to reset all dynamic indices.recovery setting a prefix can be used:

PUT /_cluster/settings
{
    "transient" : {
        "indices.recovery.*" : null
    }
}

Cluster wide settings can be returned using:

GET /_cluster/settings

Transient cluster settings take precedence over persistent cluster settings, which take precedence over settings configured in the elasticsearch.yml config file.

It’s best to set all cluster-wide settings with the settings API and use the elasticsearch.yml file only for local configurations. This way you can be sure that the setting is the same on all nodes. If, on the other hand, you define different settings on different nodes by accident using the configuration file, it is very difficult to notice these discrepancies.

A list of dynamically updatable settings can be found in the Modules documentation.