[[releasenotes]]
== Release Notes

This section summarizes the changes in the following releases:

* <<logstash-5-5-3,Logstash 5.5.3>>
* <<logstash-5-5-2,Logstash 5.5.2>>
* <<logstash-5-5-1,Logstash 5.5.1>>
* <<logstash-5-5-0,Logstash 5.5.0>>

[[logstash-5-5-3]]
=== Logstash 5.5.3 Release Notes

There are no user-facing changes in Logstash core for this release.

[[logstash-5-5-2]]
=== Logstash 5.5.2 Release Notes

* Optimized the response time for metrics releated APIs by caching the hostname ({lsissue}7857[Issue 7857]).
* Set the JVM min and max heapsize to be 1 GB out of the box. Previously, only the max heapsize was set to 1 GB.
* Fixed a condition where Logstash would not start when using persistent queue feature and a queue page file of zero byte existed with a fully acked checkpoint ({lsissue}7809[Issue 7809]).
* Fix an issue where Logstash would crash when using the dead letter queue seek by timestamp feature.
* Fixed an issue where Logstash would not reload unconditionally when SIGHUP was received with auto-reload turned off.  ({lsissue}6417[Issue 6417]) 

[[logstash-5-5-1]]
=== Logstash 5.5.1 Release Notes

* Added a new setting `dead_letter_queue.max_bytes` to allow a user to set the maximum possible size of a dead letter queue on disk.

[float]
==== Input Plugins

*`Dead Letter Queue`*: 

* Re-published this plugin to include jar artifacts. Without this, the plugin couldn't be used with Logstash.

[float]
==== Filter Plugins

*`Dissect`*: 

* Re-published this plugin to include jar artifacts. Without this, the plugin couldn't be used with Logstash.

[float]
==== Output Plugins

*`Elasticsearch`*: 

* We now correctly handle special characters in the password option.

[[logstash-5-5-0]]
=== Logstash 5.5.0 Release Notes

* Introduced a new feature called dead letter queues. When enabled, the dead letter queue (DLQ) feature will route 
  events to a file-based store when the output plugin is unable to process the events. Currently, the Elasticsearch 
  output is the only plugin that uses this feature to store "dead" events that result from Elasticsearch mapping errors.
* Upgraded to JRuby version 1.7.27.
* Set the default entropy source to `/dev/urandom`. This change resolves an issue that caused Logstash to 
  stall on startup for several minutes. This stall behavior was especially visible when Logstash was 
  deployed on VMs ({lsissue}6117[Issue 6117]).
* Added support to resolve environment variables specified in the `logstash.yml` file ({lsissue}6785[Issue 6785]).
* Fixed the ability to change log levels via the API ({lsissue}7277[Issue 7277]).

[float]
==== Filter Plugins

*`Date`*:

* A warning message is no longer logged when `ISO8601` format and timezone interpolation is used (https://github.com/logstash-plugins/logstash-filter-date/issues/97[#97]).

*`Mutate`*:

* Added a new copy option that allows users to clone a field into a new field target.