How to add authentication to Elastic Transport Client

How to add authentication to elastic transport client. Are there any opensource authentication plugins for elastic search. I tried with readonlyrest and searchguard but both of them did not satisfy my requirement.

To use transport level authentication with Search Guard do:

• Set up a transport client, and configure it to use a client certificate when talking to Elasticsearch
• Configure the Distinguished Name of the certificate as a Search Guard user. This user does not need any login credentials or roles since it is already identified by its certificate
• Send a Basic Authentication header with each request. This header contains the username and password and want to use for this request
• Search Guard will apply all security checks for the provided credentials, as if they would have been provided on the REST level
• This means you can implement access control based on indices and types, and also apply document- and field-level security on the transport level.

See also https://floragunn.com/transport-client-authentication-authorization/