Configuration Parameters

This section provides the Kafka REST Proxy for MapR Event Store For Apache Kafka parameters.

These parameters are configurable in the file.
Table 1. Configuration Parameters for Kafka REST Proxy
Parameter Description Defines the default stream for both the consumer and producer. This allows you to use topics without having the stream path included in the topic name.

Unique ID for this REST server instance. This is used in generating unique IDs for consumers that do not specify their ID. The ID is empty by default, which makes a single server setup easier to get up and running, but is not safe for multi-server deployments where automatic consumer IDs are used. Type: string. Default: empty

consumer.threads The number of threads to run consumer requests on. Type: int. Default: 1

Maximum number of records that can be stored in a single cache. Records with higher offsets replace records with lower ones. The value must be greater than 0. Type: int. Default: 1000.


Maximum number topic-partition combinations for which records are cached. If this parameter is set to 0, then caching is disabled and extra records are thrown away. Cache improves performance if records are fetched sequentially thus increasing offsets.

A pool of caches are available to store extra fetch records by a KafkaConsumer for a particular TopicPartition. The cache increases performance when records are fetched from a particular topic partition in a sequential manner. For example, every next request will start with the following offset after the offset of the latest fetched record in the previous request. Type: int. Default: 0


Specifies the maximum number of milliseconds that are spent for polling records by a simpleconsumer. The greater the value means greater latency but higher throughput. Type: int. Default: 1000


Maximum number of SimpleConsumers that can be instantiated. If 0, then the pool size is not limited. Type: int. Default: 25

Amount of time to wait for an available SimpleConsumer from the pool before failing. Use 0 for no timeout. Type: int. Default: 1000 Amount of idle time (in milliseconds) before a consumer instance is automatically destroyed. Type: int. Default: 300000 (5 minutes)

Amount of time (in milliseconds) to backoff when an iterator runs out of data. If a consumer has a dedicated worker thread, this is effectively the maximum error for the entire request timeout. This parameter should be small enough to closely target the timeout, but large enough to avoid busy waiting. Type: int. Default: 50


Maximum number of bytes in unencoded message keys and values returned by a single request. This can be used by administrators to limit the memory used by a single consumer and to control the memory usage required to decode responses on clients that cannot perform a streaming decode. Note that the actual payload will be larger due to overhead from base64 encoding the response data and from JSON encoding the entire response. Type: long. Default: 6710884

The maximum total time (in milliseconds) to wait for messages for a request if the maximum number of messages has not yet been reached. Type: int. Default: 1


Number of threads to run producer requests on. Type: int. Default: 5

Name of the SLF4J logger to write the NCSA Common Log Format request log. Type: string. Default:


The default response media type that should be used if no specify types are requested in an Accept header. Type: string. Default: application/vnd.kafka.v1+json


An ordered list of the server's preferred media types used for responses, from most preferred to least. Type: list. Default: application/vnd.kafka.v1+json, application/vnd.kafka+json, application/json


Sets the value to the Jetty Access-Control-Allow-Origin header for specified methods. Type: string. Default: empty


Sets the value for the Jetty Access-Control-Allow-Origin header. Type: string. Default: empty

The host name used to generate absolute URLs in responses. If empty, the default canonical hostname is used. Type: string. Default: empty


Boolean indicating whether extra debugging information is generated in some error response entities. Type: Boolean. Default: false

Amount of time to wait after a shutdown request for outstanding requests to complete. Type: int. Default: 1000


A list of classes to use as metrics reporters. Implementing the MetricReporterinterface allows plugging in classes that will be notified of new metric creation. The JmxReporter is always included to register JMX statistics. Type: list. Default: empty


Prefix to apply to metric names for the default JMX reporter. Type: string. Default:


The number of samples maintained to compute metrics. Type: int. Default: 2

The metrics system maintains a configurable number of samples over a fixed window size. This configuration controls the size of the window. For example, used to maintain two samples each measured over a 30 second period. When a window expires, the oldest window is erased and overwritten. Type: long. Default: 30000