File-based User Authentication

You can manage and authenticate users with the built-in file internal realm. With the file realm users are defined in local files on each node in the cluster.

Important

As the administrator of the cluster, it is your responsibility to ensure the same users are defined on every node in the cluster. X-Pack security does not deliver any mechanism to guarantee this.

The file realm is primarily supported to serve as a fallback/recovery realm. It is mostly useful in situations where all users locked themselves out of the system (no one remembers their username/password). In this type of scenarios, the file realm is your only way out - you can define a new admin user in the file realm and use it to log in and reset the credentials of all other users.

Important

When you configure realms in elasticsearch.yml, only the realms you specify are used for authentication. To use the file realm as a fallback, you must include it in the realm chain.

To define users, X-Pack security provides the users command-line tool. This tool enables you to add and remove users, assign user roles and manage user passwords.

Configuring a File Realm

The file realm is added to the realm chain by default. You don’t need to explicitly configure a file realm to manage users with the users tool.

Like other realms, you can configure options for a file realm in the xpack.security.authc.realms namespace in elasticsearch.yml.

To configure an file realm:

  1. Add a realm configuration of type file to elasticsearch.yml under the xpack.security.authc.realms namespace. At a minimum, you must set the realm type to file. If you are configuring multiple realms, you should also explicitly set the order attribute. See File Realm Settings for all of the options you can set for a file realm.

    For example, the following snippet shows a file realm configuration that sets the order to zero so the realm is checked first:

    xpack:
      security:
        authc:
          realms:
            file1:
              type: file
              order: 0
  2. Restart Elasticsearch.

File Realm Settings

Setting

Required

Description

type

yes

Indicates the realm type. Must be set to file.

order

no

Indicates the priority of this realm within the realm chain. Realms with a lower order are consulted first. Although not required, we recommend explicitly setting this value when you configure multiple realms. Defaults to Integer.MAX_VALUE.

enabled

no

Indicates whether this realm is enabled or disabled. Enables you to disable a realm without removing its configuration. Defaults to true.

cache.ttl

no

Specifies the time-to-live for cached user entries. A user’s credentials are cached for this period of time. Specify the time period using the standard Elasticsearch time units. Defaults to 20m.

cache.max_users

no

Specifies the maximum number of user entries that can be stored in the cache at one time. Defaults to 100,000.

cache.hash_algo

no

Specifies the hashing algorithm that is used for the cached user credentials. See Cache hash algorithms for the possible values. (Expert Setting).

A Look Under the Hood

All the data about the users for the file realm is stored in two files, users and users_roles. Both files are located in CONFIG_DIR/x-pack/ and are read on startup.

By default, X-Pack security checks these files for changes every 5 seconds. You can change this default behavior by changing the resource.reload.interval.high setting in the elasticsearch.yml file (as this is a common setting in Elasticsearch, changing its value may effect other schedules in the system).

Important

These files are managed locally by the node and are not managed globally by the cluster. This means that with a typical multi-node cluster, the exact same changes need to be applied on each and every node in the cluster.

A safer approach would be to apply the change on one of the nodes and have the users and users_roles files distributed/copied to all other nodes in the cluster (either manually or using a configuration management system such as Puppet or Chef).

While it is possible to modify these files directly using any standard text editor, we strongly recommend using the bin/x-pack/users command-line tool to apply the required changes.

The users File

The users file stores all the users and their passwords. Each line in the users file represents a single user entry consisting of the username and hashed password.

rdeniro:$2a$10$BBJ/ILiyJ1eBTYoRKxkqbuDEdYECplvxnqQ47uiowE7yGqvCEgj9W
alpacino:$2a$10$cNwHnElYiMYZ/T3K4PvzGeJ1KbpXZp2PfoQD.gfaVdImnHOwIuBKS
jacknich:$2a$10$GYUNWyABV/Ols/.bcwxuBuuaQzV6WIauW6RdboojxcixBq3LtI3ni
Note

X-Pack security uses bcrypt to hash the user passwords.

The users_roles File

The users_roles file stores the roles associated with the users, as in the following example:

admin:rdeniro
power_user:alpacino,jacknich
user:jacknich

Each row maps a role to a comma-separated list of all the users that are associated with that role.