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,
+    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
+
+    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))
-        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}"
+          @logger.warn(I18n.t("logstash.plugin.version.0-1-0", 
+                              :type => @plugin_type,
+                              :name => @config_name,
+                              :LOGSTASH_VERSION => LOGSTASH_VERSION))
+        end
       end
-      @@milestone_notice_given = true
+
+      @@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
-          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
+      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-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