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LogScale Self-Hosted Deployment
This is an archived version of the documentation downloaded from LogScale Documentation Archives. Up to date documentation, and documentation for later versions, is available on LogScale Documentation

### Kafka Usage

LogScale uses Apache Kafka internally for queueing incoming messages and for storing shared state when running LogScale in a cluster setup. This page describes how LogScale uses Kafka. If you already understand Kafka concepts, you can skip this and go to the instructions on how to install Kafka using containers, or on bare metal.

For more information on Kafka configuration and settings, see Kafka Configuration.

#### How LogScale Uses Kafka

LogScale creates the following queues in Kafka:

- global-events

- humio-ingest

- transientChatter

You can set the environment variable `HUMIO_KAFKA_TOPIC_PREFIX` to add that prefix to the topic names in Kafka. Adding a prefix is recommended if you share the Kafka installation with applications other than LogScale, or with another LogScale instance. The default is not to add a prefix.

LogScale configures default retention settings on the topics when it creates them. If they exist already, LogScale does not alter retention settings on the topics.

If you wish to inspect and change the topic configurations, such as the retention settings, to match your disk space available for Kafka, please use the kafka-configs command. See below for an example, modifying the retention on the ingest queue to keep burst of data for up to one hour only.

##### global-events

This is LogScale's event-sourced database queue.

- This queue has a relatively low throughput.

- Allow messages of at least 2MB or more to allow large events:

  ini

      max.message.bytes=2097152

- No log data is saved to this queue.

- There should be a high number of replicas for this queue.

- LogScale will raise the number of replicas on this queue to three if there are at least three brokers in the Kafka cluster and LogScale is allowed to manage the topic.

Default required replicas:

ini

    min.insync.replicas = 2

Provided there are three brokers when LogScale creates the topic. Default retention configuration:

ini

    retention.bytes = 1073741824

Which configures 1GB, and disable time based retention:

ini

    retention.ms = -1

Compression should be set to:

ini

    compression.type=producer

##### kafka-humio-ingest

Ingested events are sent to this queue, before they are stored in LogScale. LogScale's front end will accept ingest requests, parse them, and put them on the queue. LogScale's back end processes events from the queue and stores them into the datastore. This queue will have high throughput corresponding to the ingest load. The number of replicas can be configured in accordance with data size, latency and throughput requirements, and how important it is not to lose in-flight data.

LogScale defaults to two replicas on this queue, if at least two brokers exist in the Kafka cluster, and LogScale has not been told otherwise through the configuration parameter `INGEST_QUEUE_REPLICATION_FACTOR`, which defaults to `2`. When data is stored in LogScale's own datastore, we don't need it on the queue any more.

- Default required replicas:

  ini

      min.insync.replicas = $INGEST_QUEUE_REPLICATION_FACTOR - 1

  Provided there are enough brokers when LogScale creates the topic.

- Default retention configuration (7 days as milliseconds):

  ini

      retention.ms = 604800000

- Set the retention configuration on the `humio-ingest`topic to:

  ini

      retention.bytes = disk_space_in_bytes_on_one_host / partitionCount

  with the actual setting based on the disk space available.

- Compression should be set to:

  ini

      compression.type=producer

- Allow messages of at least 8 MB to allow large events:

  ini

      max.message.bytes=8388608

- Compaction is not allowed.

##### transientChatter-events

This queue is used for chatter between LogScale nodes. It is only used for transient data. LogScale will raise the number of replicas on this queue to `3` if there are at least three brokers in the Kafka cluster. The queue can have a short retention and it is not important to keep the data, as it gets stale very fast.

- Default required replicas (provided there are three brokers when LogScale creates the topic):

  ini

      min.insync.replicas = 2

- Default retention configuration (one hour as millis):

  ini

      retention.ms = 3600000

- Compression should be set to:

  ini

      compression.type=producer

- Support compaction settings allowing Kafka to retain only the latest copy:

  ini

      cleanup.policy=compact

#### Kafka Version

LogScale recommends that the latest Kafka version is used with your LogScale deployment. The latest version of Kafka is available at Kafka Downloads.

### Note

The minimum supported Kafka version is Kafka 2.4.1 and greater and is usually tested against the latest Kafka version.

You can set the configuration for individual topics using the following commands:

shell Syntax

    ## Example commands for setting protocol version on topic...
    # See current config for topic, if any:
    kafka-configs.sh --zookeeper localhost:2181 --describe --entity-type topics --entity-name 'humio-ingest'
    # Set protocol version for topic:
    kafka-configs.sh --zookeeper localhost:2181 --alter --entity-type topics --entity-name 'humio-ingest' --add-config 'message.format.version=0.11.0'
    # Remove setting, allowing to use the default of the broker:
    kafka-configs.sh --zookeeper localhost:2181 --alter --entity-type topics --entity-name 'humio-ingest' --delete-config 'message.format.version'

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