clean up field-reference-parser (#12466)

remove field-reference-parser for version 8
Fixed: #12355

docs/static/breaking-changes.asciidoc

@@ -15,6 +15,7 @@ NOTE: Migrating directly between non-consecutive major versions (5.x to
 
 See these topics for a description of breaking changes:
 
+* <<breaking-8.0>>
 * <<breaking-7.0>>
 * <<breaking-pq>>
 * <<breaking-6.0>>
@@ -24,6 +25,21 @@ See also <<releasenotes>>.
 //NOTE: The notable-breaking-changes tagged regions are re-used in the
 //Installation and Upgrade Guide
 
+[[breaking-8.0]]
+=== Breaking changes in 8.0
+Here are the breaking changes for 8.0.
+
+[float]
+==== Changes in Logstash Core
+
+[float]
+[[field-reference-parser]]
+===== Field Reference parser removed
+The Field Reference parser by default was STRICT in version 7. This configuration is removed permanently.
+Logstash keeps the behaviour as if the default setting, which interprets references to fields in your pipelines and plugins,
+and rejects inputs that are either ambiguous or illegal.
+
+
 [[breaking-7.0]]
 === Breaking changes in 7.0
 

logstash-core/lib/logstash/agent.rb

@@ -69,12 +69,6 @@ def initialize(settings = LogStash::SETTINGS, source_loader = nil)
     # Generate / load the persistent uuid
     id
 
-    # Set the global FieldReference parsing mode
-    if @settings.set?('config.field_reference.parser')
-      # TODO: i18n
-      logger.warn("deprecated setting `config.field_reference.parser` set; field reference parsing is strict by default")
-    end
-
     if @settings.set?('pipeline.ecs_compatibility')
       ecs_compatibility_value = settings.get('pipeline.ecs_compatibility')
       if ecs_compatibility_value != 'disabled'

logstash-core/lib/logstash/environment.rb

@@ -49,7 +49,6 @@ module Environment
            Setting::Boolean.new("config.reload.automatic", false),
            Setting::TimeValue.new("config.reload.interval", "3s"), # in seconds
            Setting::Boolean.new("config.support_escapes", false),
-            Setting::String.new("config.field_reference.parser", "STRICT", true, %w(STRICT)),
            Setting::Boolean.new("metric.collect", true),
             Setting::String.new("pipeline.id", "main"),
            Setting::Boolean.new("pipeline.system", false),

logstash-core/lib/logstash/runner.rb

@@ -84,11 +84,6 @@ class LogStash::Runner < Clamp::StrictCommand
     :default => LogStash::SETTINGS.get_default("config.string"),
     :attribute_name => "config.string"
 
-  option ["--field-reference-parser"], "MODE",
-         I18n.t("logstash.runner.flag.field-reference-parser"),
-         :attribute_name => "config.field_reference.parser",
-         :default => LogStash::SETTINGS.get_default("config.field_reference.parser")
-
   # Module settings
   option ["--modules"], "MODULES",
     I18n.t("logstash.runner.flag.modules"),

logstash-core/locales/en.yml

@@ -228,24 +228,6 @@ en:
           "%{default_output}"
           If you wish to use both defaults, please use
           the empty string for the '-e' flag.
-        field-reference-parser: |+
-          (DEPRECATED) This option is no longer
-          configurable.
-
-          Use the given MODE when parsing field
-          references.
-
-          The field reference parser is used to expand
-          field references in your pipeline configs,
-          and has become more strict to better handle
-          ambiguous- and illegal-syntax inputs.
-
-          The only available MODE is:
-           - `STRICT`: parse in a strict manner; when
-             given ambiguous- or illegal-syntax input,
-             raises a runtime exception that should
-             be handled by the calling plugin.
-
         modules: |+
           Load Logstash modules.
           Modules can be defined using multiple instances