A behaviour module for implementing a Cassandra authenticator.

Examples

defmodule MyAuthenticator do
  @behaviour Xandra.Authenticator

  def response_body(options) do
    ["user:", Keyword.fetch!(options, :user), "_password:", Keyword.fetch!(options, :password)]
  end
end

To use the authenticator defined above:

Xandra.start_link(authentication: {MyAuthenticator, user: "foo", password: "bar"})

Xandra supports Cassandra's PasswordAuthenticator by default, see Xandra.Authenticator.Password for more information.

Challenge-based Authentication

Some authenticators (such as AWS Keyspaces' SigV4 mechanism) require an additional challenge round-trip: after the initial AUTH_RESPONSE, the server replies with an AUTH_CHALLENGE message that the client has to answer with another AUTH_RESPONSE. To support these authenticators, you have to implement the optional challenge_response_body/2 callback. If it's defined, Xandra calls it with the challenge sent by the server whenever it receives an AUTH_CHALLENGE message.

defmodule MyChallengeAuthenticator do
  @behaviour Xandra.Authenticator

  @impl true
  def response_body(_options) do
    "SigV4\0\0"
  end

  @impl true
  def challenge_response_body(challenge, options) do
    sign(challenge, options)
  end
end