AWS MSK has an optional IAM auth feature that enables to use AWS IAM policies for managing authentication/authorization to Kafka resources instead of Kafka ACLs. More information in the AWS MSK documentation.

This change

• includes the AWS library for MSK IAM auth that provides a new SASL mechanism AWS_MSK_IAM
• adds a config option sasl.client.callback.handler.class to allow providing custom SASL callback handlers
• in previous plugin versions the transitive Jar dependencies were not exported. The AWS MSK IAM auth library is a jar without dependencies, this caused issues with finding various AWS classes. Instead of listing all the transitive AWS dependencies, this change also modifies build.gradle to export all Jar dependencies and add them to the jars file. If a transitive dependency should not be exported, the transitive=false flag can be used.

Tested both input and output on an AWS EC2 machine with AWS MSK (Kafka version 2.6.2) and Logstash 8.2.3.

Usage as input/output:

 kafka {
    topic_id => "yourtopic"
    bootstrap_servers => "yourbroker"
    security_protocol => "SASL_SSL"
    sasl_mechanism => "AWS_MSK_IAM"
    sasl_jaas_config => "software.amazon.msk.auth.iam.IAMLoginModule required;"
    sasl_client_callback_handler_class => "software.amazon.msk.auth.iam.IAMClientCallbackHandler"
  }

This PR also fixes the issue #124

Closes: #124