Class: Karafka::Web::Management::Actions::CreateTopics

Inherits:
Base
  • Object
show all
Defined in:
lib/karafka/web/management/actions/create_topics.rb

Overview

Creates all the needed topics (if they don’t exist). It does not populate data.

Instance Method Summary collapse

Instance Method Details

#call(replication_factor) ⇒ Object

Note:

The order of creation of those topics is important. In order to support the zero-downtime bootstrap, we use the presence of the states topic and its initial state existence as an indicator that the setup went as expected. It the consumers states topic exists and contains needed data, it means all went as expected and that topics created before it also exist (as no error).

Runs the creation process

Parameters:

  • replication_factor (Integer) —

    replication factor for Web-UI topics



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# File 'lib/karafka/web/management/actions/create_topics.rb', line 19

def call(replication_factor)
  consumers_states_topic = ::Karafka::Web.config.topics.consumers.states
  consumers_metrics_topic = ::Karafka::Web.config.topics.consumers.metrics
  consumers_reports_topic = ::Karafka::Web.config.topics.consumers.reports
  consumers_commands_topic = ::Karafka::Web.config.topics.consumers.commands
  errors_topic = ::Karafka::Web.config.topics.errors

  if existing_topics_names.include?(errors_topic.name)
    exists(errors_topic.name)
  else
    creating(errors_topic.name)
    # All the errors will be dispatched here
    # This topic can have multiple partitions but we go with one by default. A single
    # Ruby process should not crash that often and if there is an expectation of a higher
    # volume of errors, this can be changed by the end user
    ::Karafka::Admin.create_topic(
      errors_topic.name,
      1,
      replication_factor,
      errors_topic.config
    )
    created(errors_topic.name)
  end

  if existing_topics_names.include?(consumers_reports_topic.name)
    exists(consumers_reports_topic.name)
  else
    creating(consumers_reports_topic.name)
    # This topic needs to have one partition
    ::Karafka::Admin.create_topic(
      consumers_reports_topic.name,
      1,
      replication_factor,
      consumers_reports_topic.config
    )
    created(consumers_reports_topic.name)
  end

  if existing_topics_names.include?(consumers_metrics_topic.name)
    exists(consumers_metrics_topic.name)
  else
    creating(consumers_metrics_topic.name)
    # This topic needs to have one partition
    # Same as states - only most recent is relevant as it is a materialized state
    ::Karafka::Admin.create_topic(
      consumers_metrics_topic.name,
      1,
      replication_factor,
      consumers_metrics_topic.config
    )
    created(consumers_metrics_topic.name)
  end

  if existing_topics_names.include?(consumers_commands_topic.name)
    exists(consumers_commands_topic.name)
  else
    creating(consumers_commands_topic.name)
    # Commands are suppose to live short and be used for controlling processes and some
    # debug. Their data can be removed safely fast.
    ::Karafka::Admin.create_topic(
      consumers_commands_topic.name,
      1,
      replication_factor,
      consumers_commands_topic.config
    )
    created(consumers_commands_topic.name)
  end

  # Create only if needed
  if existing_topics_names.include?(consumers_states_topic.name)
    exists(consumers_states_topic.name)
  else
    creating(consumers_states_topic.name)
    # This topic needs to have one partition
    ::Karafka::Admin.create_topic(
      consumers_states_topic.name,
      1,
      replication_factor,
      consumers_states_topic.config
    )
    created(consumers_states_topic.name)
  end
end