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Status

Current state[Under Discussion]Accepted

Discussion thread: here 

Vote thread: here 

JIRA

Jira
serverASF JIRA
serverId5aa69414-a9e9-3523-82ec-879b028fb15b
keyKAFKA-9958

...

Current Kafka authorizer plugin cannot access to Kafka broker metrics information.  Kafka authorizer plugins need access to runtime broker Metrics instance to add additional metrics.  There is disconnection for between how to manage Metrics between broker and authorizer plugins in current Kafka implementation. The authorizer plugins as plugins of broker could use same Metrics instance in broker, so authorizer plugins need not manage tasks like creating and configuring Metrics and JmxReporter. With the feature of this KIP, authorizer plugin can use broker's Metrics instance to add additional metrics very easy.

...

Define a new interface Monitorable in package org.apache.kafka.common. The authorizer plugins can implement the interface and broker can pass the instance of Metrics to Authorizer. Other  Other broker'd or client's plugins could potentially implement the interface in the future and get the broker's or client's Metrics instance tonadd to add additional metrics from sub-components. Support for other plugins will be addressed later in another KIP if necessary. This KIP will focus on exposing Kafka Metrics in Authorizer only.

Code Block
languagejava
titleBroker Runtime ConfigMonitorable Interface
package org.apache.kafka.common;

import org.apache.kafka.common.metrics.Metrics;

/**
 * Interface for plugins to get Metrics instance
 */
public interface Monitorable {
    /**
     * Get the instance of {@link Metrics}.
     */
    default void monitor(Metrics metrics) {
		return;
	};
}


The org.apache.kafka.server.authorizer.Authorizer interface need be updated to extend Monitorable Interface.

Code Block
languagejava
titleAuthorizer Interface
package org.apache.kafka.server.authorizer.Authorizer
... 
import org.apache.kafka.common.Monitorable;
...
public interface Authorizer extends Configurable, Closeable, Monitorable {
...
}


The following metrics will be added:

Full NameTypeDescription
kafka.server:type=kafka.security.authorizer.metrics,name=acls-total-count32-bit gaugeTotal acls created in the broker
kafka.server:type=kafka.security.authorizer.metrics,name=authorization-request-rate-per-minuteRate per minuteTotal number of authorization requests per minute
kafka.server:type=kafka.security.authorizer.metrics,name=authorization-allowed-rate-per-minuteRate per minuteTotal number of authorization allowed per minute
kafka.server:type=kafka.security.authorizer.metrics,name=authorization-denied-rate-per-minuteRate per minuteTotal number of authorization denied per minute 

Proposed Changes

kafka.server.KafkaServer will be updated to pass instance of Metrics to Authorizer.

...

kafka.security.authorizer.AclAuthorizer will be updated for adding following Kafka metrics
Metrics group name: "kafka.security.authorizer.metrics"
Metric "acls-total-count" for reporting total acls created.
Metric "authorization-request-rate-per-minute" for reporting total number of authorization requests per minute
Metric "authorization-allowed-rate-per-minute" for reporting total number of authorization allowed per minute
Metric "authorization-denied-rate-per-minute" for reporting total number of authorization denied per minute    to collect and add Authorizer metrics.

Code Block
languagescala
titlekafka.security.authorizer.AclAuthorizer
class AclAuthorizer extends Authorizer with Logging with Monitorable {
......
	private var authorizerMetrics: AuthorizerMetrics = _
......
	override def monitor(metrics: Metrics): Unit = {
    	authorizerMetrics = new AuthorizerMetrics(metrics)
  	}
......

	private def authorizeAction(requestContext: AuthorizableRequestContext, action: Action): AuthorizationResult = {
		......
		// Record authorization requests
    	authorizerMetrics.recordAuthorizationRequest()

		logAuditMessage(requestContext, action, authorized)
    	if 		authorizerMetrics.recordAuthorizerMetrics(authorized) {
      		authorizerMetrics.recordAuthorizationAllowed()
      		AuthorizationResult.ALLOWED
    	} else {
      		authorizerMetrics.recordAuthorizationDenied()
      			if (authorized) AuthorizationResult.ALLOWED else AuthorizationResult.DENIED
    	}
	}...

	class AuthorizerMetrics(metrics: Metrics) {
    	val GROUP_NAME = "kafka.security.authorizer.metrics"
    	val authorizationAllowedSensor = metrics.sensor("authorizer-authorization-allowed")
    	authorizationAllowedSensor.add(metrics.metricName("authorization-allowed-rate-per-minute", GROUP_NAME,
      		"The number of authoization allowed per hour"), new Rate(TimeUnit.MINUTES, new WindowedCount()))

    	val authorizationDeniedSensor = metrics.sensor("authorizer-authorization-denied")
    	authorizationDeniedSensor.add(metrics.metricName("authorization-denied-rate-per-minute", GROUP_NAME,
      		"The number of authoization denied per hour"), new Rate(TimeUnit.MINUTES, new WindowedCount()))

    	val authorizationRequestSensor = metrics.sensor("authorizer-authorization-request")
    	authorizationRequestSensor.add(metrics.metricName("authorization-request-rate-per-minute", GROUP_NAME,
      		"The number of authoization request per hour"), new Rate(TimeUnit.MINUTES, new WindowedCount()))

    	metrics.addMetric(metrics.metricName("acls-total-count", GROUP_NAME, "The number of acls defined"), (config, now) => aclCache.size)

    	def recordAuthorizationAllowedrecordAuthorizerMetrics(authorized: Boolean): Unit = {
      		authorizationAllowedSensor.recordif (authorized) {
        		}authorizationAllowedSensor.record()

    	def recordAuthorizationDenied(): Unit = 		} else {
        		authorizationDeniedSensor.record()
    	}

    	def recordAuthorizationRequest(): Unit = {		}
      		authorizationRequestSensor.record()
    	}
  	}
}

...

Authorizer plugins create and configure own Metrics and JmxReport. Using this alternative approach make collecting Kafka metrics in Authorizer plugin separate from broker metrics that cause disconnection. Users need implement and manage own Metrics and JmsReport with extra effort

Pass the instance of Metrics through AuthorizerServerInfo interface. The instance of Metrics should not be part of Authorizer server information. We use an interface to expose Kafka Metrics so that other broker's or client's plugins could potentially implement the interface