brod_gssapi is an authentication backend for brod. brod_gssapi makes it possible to connect Brod to a Kafka cluster using the SASL/GSSAPI (Kerberos) authentication method. Please see the configuration section below for information about which Kafka handshake versions that are supported. brod_gssapi uses sasl_auth, which is an Erlang wrapper for a SASL/GSSAPI C library.

1. Install the dependencies for sasl_auth. More information about sasl_auth's dependencies can be found in sasl_auth's README.md file.
2. Add brod_gssapi as dependency to your top level project that uses brod.
3. Add {sasl, {callback, brod_gssapi, {gssapi, Keytab, Principal}}} to the brod client config. Keytab should be the keytab file path, and Principal should be a byte list or binary string.

The example/ directory in this repository contains a docker-compose project with Kerberos, Zookeeper, Kafka (with SASL/GSSAPI Kerberos authentication) and a Brod client. The example/README.md file describes how to run this example. The code in example/brod_client/src/example.erl sets up a Brod client with SASL/GSSAPI (Kerberos) authentication and sends and receives messages.

Please see sasl_auth's README.md file for information about what software you need to install before compiling and using this plugin.

$ rebar3 compile

$ rebar3 ct

The example in the example/ directory also works as a test case. The example/README.md file describes how to run the example.

For version of Brod before 3.16.4 the handshake version used for authentication with Kafka is not passed down to the brod_gssapi plugin. By default, brod_gssapi will use the legacy handshake version (the version used before handshake version naming was introduced to Kafka). This can be changed by configuring brod_gssapi with the setting default_handshake_vsn. brod_gssapi currently only supports the legacy and 1 handshake versions. Handshake version 0 is currently not supported. The setting can be changed both programmatically with application:set_env(brod_gssapi, default_handshake_vsn, 1) and by giving the following parameter to the Erlang command -brod_gssapi default_handshake_vsn 1.