Use the gem specification from the plugin to display the version notice to the user

Fixes #2331

lib/logstash/config/mixin.rb

@@ -39,6 +39,8 @@ module LogStash::Config::Mixin
     Regexp => 100,
   }
 
+  GEM_NAME_PREFIX = 'logstash'
+
   # This method is called when someone does 'include LogStash::Config'
   def self.included(base)
     # Add the DSL methods to the 'base' given.
@@ -121,13 +123,16 @@ module LogStash::Config::Mixin
       return @config_name
     end
 
+    # Deprecated: Declare the version of the plugin
+    # inside the gemspec.
     def plugin_status(status=nil)
       milestone(status)
     end
 
+    # Deprecated: Declare the version of the plugin
+    # inside the gemspec.
     def milestone(m=nil)
-      @milestone = m if !m.nil?
-      return @milestone
+      @logger.error(I18n.t('logstash.plugin.deprecated'))
     end
 
     # Define a new configuration setting
@@ -184,7 +189,7 @@ module LogStash::Config::Mixin
         end
       end
       subclass.instance_variable_set("@config", subconfig)
-      @@milestone_notice_given = false
+      @@version_notice_given = false
     end # def inherited
 
     def validate(params)
@@ -193,7 +198,7 @@ module LogStash::Config::Mixin
       @logger = Cabin::Channel.get(LogStash)
       is_valid = true
 
-      is_valid &&= validate_milestone
+      is_valid &&= validate_plugin_version
       is_valid &&= validate_check_invalid_parameter_names(params)
       is_valid &&= validate_check_required_parameter_names(params)
       is_valid &&= validate_check_parameter_values(params)
@@ -201,23 +206,36 @@ module LogStash::Config::Mixin
       return is_valid
     end # def validate
 
-    def validate_milestone
-      return true if @@milestone_notice_given
-      docmsg = "For more information about plugin milestones, see http://logstash.net/docs/#{LOGSTASH_VERSION}/plugin-milestones "
-      plugin_type = ancestors.find { |a| a.name =~ /::Base$/ }.config_name
-      case @milestone
-        when 0,1,2
-          @logger.warn(I18n.t("logstash.plugin.milestone.#{@milestone}", 
-                              :type => plugin_type, :name => @config_name,
-                              :LOGSTASH_VERSION => LOGSTASH_VERSION))
-        when 3
-          # No message to log for milestone 3 plugins.
-        when nil
-          raise "#{@config_name} must set a milestone. #{docmsg}"
-        else
-          raise "#{@config_name} set an invalid plugin status #{@milestone}. Valid values are 0, 1, 2, or 3. #{docmsg}"
+    def plugin_version
+      specification = Gem::Specification.find_by_name(plugin_gem_name)
+      major, minor, patch = specification.version.segments
+
+      Struct.new(:major, :minor, :patch)
+        .new(major, minor, patch)
     end
-      @@milestone_notice_given = true
+
+    def plugin_gem_name
+      [GEM_NAME_PREFIX, @plugin_type, @plugin_name].join('-')
+    end
+
+    def validate_plugin_version
+      return true if @@version_notice_given
+
+      if plugin_version.major < 1
+        if plugin_version.minor == 9
+          @logger.warn(I18n.t("logstash.plugin.version.0-9-0", 
+                              :type => @plugin_type,
+                              :name => @config_name,
+                              :LOGSTASH_VERSION => LOGSTASH_VERSION))
+        else
+          @logger.warn(I18n.t("logstash.plugin.version.0-1-0", 
+                              :type => @plugin_type,
+                              :name => @config_name,
+                              :LOGSTASH_VERSION => LOGSTASH_VERSION))
+        end
+      end
+
+      @@version_notice_given = true
       return true
     end
 

locales/en.yml

@@ -34,23 +34,22 @@ en:
         supported by this plugin. I will continue working as if you had not set
         this setting.
     plugin:
-      milestone:
-        "0": >-
-          Using milestone 0 %{type} plugin '%{name}'. This plugin isn't well
-          supported by the community and likely has no maintainer. For more
-          information on plugin milestones, see
-          http://logstash.net/docs/%{LOGSTASH_VERSION}/plugin-milestones
-        "1": >-
-          Using milestone 1 %{type} plugin '%{name}'. This plugin should work,
-          but would benefit from use by folks like you. Please let us know if you
+      deprecated_milestone: >-
+        %{plugin} plugin is using the 'milestone' method to declare the version
+        of the plugin this method is deprecated in favor of declaring the
+        version inside the gemspec.
+      version:
+        0-9-0:
+         Using version 0.9.x %{type} plugin '%{name}'. This plugin should but
+         would benefit from use by folks like you. Please let us know if you
          find bugs or have suggestions on how to improve this plugin. For more
          information on plugin milestones, see
-          http://logstash.net/docs/%{LOGSTASH_VERSION}/plugin-milestones
-        "2": >-
-          Using milestone 2 %{type} plugin '%{name}'. This plugin should be
-          stable, but if you see strange behavior, please let us know!
-          For more information on plugin milestones, see
-          http://logstash.net/docs/%{LOGSTASH_VERSION}/plugin-milestones
+         http://logstash.net/docs/%{LOGSTASH_VERSION}/plugin-version
+        0-1-0: >-
+         Using version 0.1.x %{type} plugin '%{name}'. This plugin isn't well
+         supported by the community and likely has no maintainer. For more
+         information on plugin milestones, see
+         http://logstash.net/docs/%{LOGSTASH_VERSION}/plugin-version
     agent:
       sighup: >-
         SIGHUP received.

spec/core/plugin_spec.rb

@@ -29,4 +29,60 @@ describe LogStash::Plugin do
     end
     expect(LogStash::Plugin.lookup("filter", "lady_gaga")).to eq(LogStash::Filters::LadyGaga)
   end
+
+  context "when validating the plugin version" do
+    let(:plugin_name) { 'logstash-filter-stromae' }
+    subject do
+      Class.new(LogStash::Filters::Base) do
+        config_name 'stromae'
+      end
+    end
+
+    it "doesn't warn the user if the version is superior or equal to 1.0.0" do
+      allow(Gem::Specification).to receive(:find_by_name)
+        .with(plugin_name)
+        .and_return(double(:version => Gem::Version.new('1.0.0')))
+
+      expect_any_instance_of(Cabin::Channel).not_to receive(:warn)
+      subject.validate({})
+    end
+
+    it 'warns the user if the plugin version is between 0.9.x and 1.0.0' do
+      allow(Gem::Specification).to receive(:find_by_name)
+        .with(plugin_name)
+        .and_return(double(:version => Gem::Version.new('0.9.1')))
+
+      expect_any_instance_of(Cabin::Channel).to receive(:warn)
+        .with(/Using version 0.9.x/)
+
+      subject.validate({})
+    end
+
+    it 'warns the user if the plugin version is inferior to 0.9.x' do
+      allow(Gem::Specification).to receive(:find_by_name)
+        .with(plugin_name)
+        .and_return(double(:version => Gem::Version.new('0.1.1')))
+
+      expect_any_instance_of(Cabin::Channel).to receive(:warn)
+        .with(/Using version 0.1.x/)
+      subject.validate({})
+    end
+
+    it "doesnt show the version notice more than once" do
+      class LogStash::Filters::Stromae < LogStash::Filters::Base
+        config_name "stromae"
+      end
+
+      allow(Gem::Specification).to receive(:find_by_name)
+        .with(plugin_name)
+        .and_return(double(:version => Gem::Version.new('0.1.1')))
+
+      expect_any_instance_of(Cabin::Channel).to receive(:warn)
+        .once
+        .with(/Using version 0.1.x/)
+
+      LogStash::Filters::Stromae.validate({})
+      LogStash::Filters::Stromae.validate({})
+    end
+  end
 end