[role="xpack"]
[[security-api-clear-cache]]
=== Clear Cache API

The Clear Cache API evicts users from the user cache. You can completely clear
the cache or evict specific users.

==== Request

`POST _xpack/security/realm/<realms>/_clear_cache` +

`POST _xpack/security/realm/<realms>/_clear_cache?usernames=<usernames>`


==== Description

User credentials are cached in memory on each node to avoid connecting to a
remote authentication service or hitting the disk for every incoming request.
There are realm settings that you can use to configure the user cache. For more
information, see {xpack-ref}/controlling-user-cache.html[Controlling the User Cache].

==== Path Parameters

`realms` (required)::
  (list) A comma-separated list of the realms to clear.

`usernames`::
  (list) A comma-separated list of the users to clear from the cache. If you
  do not specify this parameter, the API evicts all users from the user cache.

==== Examples

For example, to evict all users cached by the `file` realm:

[source,js]
--------------------------------------------------
POST _xpack/security/realm/default_file/_clear_cache
--------------------------------------------------
// CONSOLE

To evict selected users, specify the `usernames` parameter:

[source,js]
--------------------------------------------------
POST _xpack/security/realm/default_file/_clear_cache?usernames=rdeniro,alpacino
--------------------------------------------------
// CONSOLE

To clear the caches for multiple realms, specify the realms as a comma-delimited
list:

[source, js]
------------------------------------------------------------
POST _xpack/security/realm/default_file,ldap1/_clear_cache
------------------------------------------------------------
// CONSOLE