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HTTP basic authentication

HTTP basic authentication provides a simple challenge-and-response process for gaining access to OpenSearch and its resources that prompts you to sign in with a username and password. You enable HTTP basic authentication in the http_authenticator section of the configuration by specifying type as basic, as shown in the following example:

authc:
  basic_internal_auth_domain:
    description: "Authenticate using HTTP basic against the internal users database"
    http_enabled: true
    transport_enabled: true
    order: 1
    http_authenticator:
      type: basic
      challenge: true
    authentication_backend:
      type: internal

Additionally, you can specify the internal user database as the authentication backend by specifying internal as the type for authentication_backend. See The internal user database for information about this backend.

Once basic is specified for the type of HTTP authenticator and internal is specified for the type of authentication backend, no further configuration in config.yml is needed, unless you plan to use additional authentication backends with HTTP basic authentication. Continue reading for considerations related to this type of setup and more information about the challenge setting.

The challenge setting

In most cases, it’s appropriate to set challenge to true for basic authentication. This setting defines the behavior of the Security plugin when the Authorization field in the HTTP header is not specified. By default, the setting is true.

When challenge is set to true, the Security plugin sends a response with the status UNAUTHORIZED (401) back to the client. If the client is accessing the cluster with a browser, this triggers the authentication dialog box and the user is prompted to enter a username and password. This is a common configuration when HTTP basic authentication is the only backend being used.

When challenge is set to false and an Authorization header has not been specified in the request, the Security plugin does not send a WWW-Authenticate response back to the client, and authentication fails. This configuration is often used when you have multiple challenging http_authenticator settings included in your configured authentication domains. This might be the case, for example, when you plan to use basic authentication and SAML together. For an example and a more complete explanation of this configuration, see Running multiple authentication domains in the SAML documentation.

When you define multiple HTTP authenticators, make sure to order non-challenging authenticators first—such as proxy and clientcert—and order challenging HTTP authenticators last. For example, in a configuration where a non-challenging HTTP basic authentication backend is paired with a challenging SAML backend, you might specify order: 0 in the HTTP basic authc domain and order: 1 in the SAML domain.

The internal user database

When using HTTP basic authentication, the internal user database stores the internal users and includes their hashed passwords and other user attributes, such as roles. Users and their settings are kept in the internal_users.yml configuration file. For more information about this file, see internal_users.yml in the security configuration documentation.