AuthenticationBackend (Search Guard Suite - Security 7.6.0-41.2.0 API)

All Known Implementing Classes:

InternalAuthenticationBackend, NoOpAuthenticationBackend
```
public interface AuthenticationBackend
```
Search Guard custom authentication backends need to implement this interface.
Authentication backends verify AuthCredentials and, if successfully verified, return a User.
Implementation classes must provide a public constructor
public MyHTTPAuthenticator(org.elasticsearch.common.settings.Settings settings, java.nio.file.Path configPath)
The constructor should not throw any exception in case of an initialization problem. Instead catch all exceptions and log a appropriate error message. A logger can be instantiated like:
private final Logger log = LogManager.getLogger(this.getClass());
Custom authenticators is a commercial feature. To make them work you need to obtain a license here: https://floragunn.com

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`User`	`authenticate(AuthCredentials credentials)`	Validate credentials and return an authenticated user (or throw an ElasticsearchSecurityException)
`boolean`	`exists(User user)`	Lookup for a specific user in the authentication backend
`String`	`getType()`	The type (name) of the authenticator.

- Method Detail
  - getType
```
String getType()
```
    The type (name) of the authenticator. Only for logging.
    
    Returns:
    
    the type
  - authenticate
```
User authenticate(AuthCredentials credentials)
           throws org.elasticsearch.ElasticsearchSecurityException
```
    Validate credentials and return an authenticated user (or throw an ElasticsearchSecurityException)
    Results of this method are normally cached so that we not need to query the backend for every authentication attempt.
    
    Parameters:
    
    The - credentials to be validated, never null
    
    Returns:
    
    the authenticated User, never null
    
    Throws:
    
    org.elasticsearch.ElasticsearchSecurityException - in case an authentication failure (when credentials are incorrect, the user does not exist or the backend is not reachable)
  - exists
```
boolean exists(User user)
```
    Lookup for a specific user in the authentication backend
    
    Parameters:
    
    user - The user for which the authentication backend should be queried. If the authentication backend supports user attributes in combination with impersonation the attributes needs to be added to user by calling user.addAttributes()
    
    Returns:
    
    true if the user exists in the authentication backend, false otherwise. Before return call user.addAttributes() as explained above.