Quota Plugin for Apache Kafka®

This project is based on https://github.com/lulf/kafka-static-quota-plugin and was originally created by Ulf Lilleengen.

This is a broker quota plugin for Apache Kafka® to allow setting a per-broker limits statically in the broker configuration.

The default quota plugin in Apache Kafka will hand out a unique quota per client. This plugin will configure a total quota independent of the number of clients. For example, if you have configured a produce quota of 40 MB/second, and you have 10 producers running as fast as possible, they will be limited by 4 MB/second each.

The quota distribution across clients is not static. If you have a max of 40 MB/second, 2 producers, and one of them is producing messages at 10 MB/second, the second producer will be throttled at 30 MB/second.

Using with Strimzi

Warning: this version is not included in Strimzi yet, see tag 0.2.0 for current Strimzi-compatible docs.

Using with other Apache Kafka clusters

The Quota plugin can be also used with non-Strimzi Apache Kafka clusters. You have to add the plugin JAR file to the Apache Kafka broker class path for example by copying it to the libs/ directory. Configure Apache Kafka brokers to load the plugin and configure it in the broker properties file:

# Enable the Quota plugin
client.quota.callback.class=io.strimzi.kafka.quotas.StaticQuotaCallback

# The quota is given in bytes, and will translate to bytes/sec in total for your clients
# In this example configuration the produce and fetch quota is set to 1MB/s
client.quota.callback.static.produce=1000000
client.quota.callback.static.fetch=1000000

client.quota.callback.static.kafka.admin.bootstrap.servers=localhost:9092 # required if storage.check-interval is >0
client.quota.callback.static.kafka.admin.ssl.truststore.location=/tmp/trust.jks # optionally configure the admin client further
# Storage quota settings in bytes. Clients will be throttled to 0 when any volume in the cluster has <= 5GB available bytes
client.quota.callback.static.storage.per.volume.limit.min.available.bytes=5368709120

# Check storage usage every 5 seconds
# By default set to 60 seconds
client.quota.callback.static.storage.check-interval=5

# Optional list of principals not to be subjected to the quota
client.quota.callback.static.excluded.principal.name.list=User:principal1;User:principal2

Properties and their defaults

Property	Type	Default	Description
client.quota.callback.static.produce	Double	1.7976931348623157e+308	Produce bandwidth rate quota (in bytes)
client.quota.callback.static.fetch	Double	1.7976931348623157e+308	Consume bandwidth rate quota (in bytes)
client.quota.callback.static.request	Double	1.7976931348623157e+308	Request processing time quota (in seconds)
client.quota.callback.static.excluded.principal.name.list	String	""	Semicolon-separated list of principals excluded from the quota. Each principal has to be prefixed with User:.
client.quota.callback.static.storage.check-interval	Integer	60	Interval between storage check runs (in seconds, a value of 0 means disabled)
client.quota.callback.static.storage.per.volume.limit.min.available.bytes	Long	None	Stop message production if availableBytes <= this value. Mutually exclusive with client.quota.callback.static.storage.per.volume.limit.min.available.ratio.
client.quota.callback.static.storage.per.volume.limit.min.available.ratio	Double	None	Stop message production if availableBytes / capacityBytes <= this value. Mutually exclusive with client.quota.callback.static.storage.per.volume.limit.min.available.bytes.
client.quota.callback.static.throttle.factor.fallback	Double	1.0	Fallback throttle factor to apply, in the range 0..1 if current factor expires. Applied by multiplying the factor against client.quota.callback.static.produce thus 0.0 effectively blocks producers.
client.quota.callback.static.throttle.factor.validity.duration	String	PT5M	How long a throttle factor derived from a successful observation of the cluster should be applied (iso8601 duration)
client.quota.callback.static.kafka.admin.bootstrap.servers	String	None	Bootstrap servers of Kafka cluster. This property is required, otherwise the Kafka broker will fail to start.

All configuration properties starting with client.quota.callback.static.kafka.admin. prefix will be passed to the Kafka Admin client configuration.

Metrics

The plugin currently provides the following metrics:

• io.strimzi.kafka.quotas:type=StaticQuotaCallback,name=Produce shows the currently configured produce quota
• io.strimzi.kafka.quotas:type=StaticQuotaCallback,name=Fetch shows the currently configured fetch quota
• io.strimzi.kafka.quotas:type=StaticQuotaCallback,name=Request shows the currently configured request quota

NOTE: Only one quota plugin can be used in Kafka. Enabling this plugin, the built-in Kafka quotas plugin will be automatically disabled. This means that you won't see per-client quota metrics, but only aggregated quota metrics.

Additional metrics for cluster wide monitoring

Name	Metric Type	Meaning	Type	Tags
ThrottleFactor	Gauge	The current factor applied by the plug-in [0..1]	ThrottleFactor	observingBrokerId
FallbackThrottleFactorApplied	Counter	The number of times the plug-in has transitioned to using the fall back factor	ThrottleFactor	observingBrokerId
LimitViolated	Counter	A count of the number logDirs which violate the configured limit	ThrottleFactor	observingBrokerId
ActiveBrokers	Gauge	The current number of brokers returned by the describeCluster rpc	VolumeSource	observingBrokerId
ActiveLogDirs	Gauge	The number of logDirs returned by the describeLogDirs RPC	VolumeSource	observingBrokerId
AvailableBytes	Gauge	The number of available bytes returned by the describeLogDirs RPC	VolumeSource	[observingBrokerId, remoteBrokerId, logDir]
ConsumedBytes	Gauge	The number of consumed bytes returned by the describeLogDirs RPC	VolumeSource	[observingBrokerId, remoteBrokerId, logDir]
CachedEntries	Gauge	The number of logDirs currently cached by the plug-in	CachingVolumeObserver	observingBrokerId
LogDirEvictions	Counter	The number of times each remoteBroker.logDir has been removed from the cache.	CachingVolumeObserver	[observingBrokerId, remoteBrokerId, logDir]

Tag definitions

Tag	Definition
observingBrokerId	The BrokerId of the broker node executing the plug-in
remoteBrokerId	The BrokerId of the broker node hosting the logDir
logDir	The path to the specific logDir as returned by the describeLogDirs RPC

Building

To build the plugin:

mvn package

Copy the resulting jar in target/kafka-quotas-plugin.jar into the Kafka classpath.

Alternatively, you can publish to your local maven repository with:

mvn install

Testing locally

Run it locally (make sure your server.properties enables the reporter):

CLASSPATH=/path/to/target/kafka-quotas-plugin.jar ./bin/kafka-server-start.sh server.properties