Exclude pre releases when checking if the update is targetting a major release in the plugin manager, as bundler is not going to update anyway to this version without an explicit install command.

Fixes #3826

lib/pluginmanager/update.rb

@@ -44,7 +44,7 @@ class LogStash::PluginManager::Update < LogStash::PluginManager::Command
     filtered_plugins = plugins.map { |plugin| gemfile.find(plugin) }
       .compact
       .reject { |plugin| REJECTED_OPTIONS.any? { |key| plugin.options.has_key?(key) } }
-      .select { |plugin| validate_major_version(plugin.name) }
+      .select { |plugin| validates_version(plugin.name) }
       .each   { |plugin| gemfile.update(plugin.name) }
 
     # force a disk sync before running bundler
@@ -67,16 +67,8 @@ class LogStash::PluginManager::Update < LogStash::PluginManager::Command
 
   # validate if there is any major version update so then we can ask the user if he is
   # sure to update or not.
-  def validate_major_version(plugin)
-    require "gems"
-    latest_version  = Gems.versions(plugin)[0]['number'].split(".")
-    current_version = Gem::Specification.find_by_name(plugin).version.version.split(".")
-    if (latest_version[0].to_i > current_version[0].to_i)
-      ## warn if users want to continue
-      puts("You are updating #{plugin} to a new version #{latest_version.join('.')}, which may not be compatible with #{current_version.join('.')}. are you sure you want to proceed (Y/N)?")
-      return ( "y" == STDIN.gets.strip.downcase ? true : false)
-    end
-    true
+  def validates_version(plugin)
+    LogStash::PluginManager.update_to_major_version?(plugin)
   end
 
   # create list of plugins to update

lib/pluginmanager/util.rb

@@ -37,6 +37,34 @@ module LogStash::PluginManager
     end
   end
 
+  # Fetch latest version information as in rubygems
+  # @param [String] The plugin name
+  # @param [Hash] Set of available options when fetching the information
+  # @option options [Boolean] :pre Include pre release versions in the search (default: false)
+  # @return [Hash] The plugin version information as returned by rubygems
+  def self.fetch_latest_version_info(plugin, options={})
+    require "gems"
+    exclude_prereleases =  options.fetch(:pre, false)
+    versions = Gems.versions(plugin)
+    versions = versions.select { |version| !version["prerelease"] } if !exclude_prereleases
+    versions.first
+  end
+
+  # Let's you decide to update to the last version of a plugin if this is a major version
+  # @param [String] A plugin name
+  # @return [Boolean] True in case the update is moving forward, false otherwise
+  def self.update_to_major_version?(plugin_name)
+    plugin_version  = fetch_latest_version_info(plugin_name)
+    latest_version  = plugin_version['number'].split(".")
+    current_version = Gem::Specification.find_by_name(plugin_name).version.version.split(".")
+    if (latest_version[0].to_i > current_version[0].to_i)
+      ## warn if users want to continue
+      puts("You are updating #{plugin_name} to a new version #{latest_version.join('.')}, which may not be compatible with #{current_version.join('.')}. are you sure you want to proceed (Y/N)?")
+      return ( "y" == STDIN.gets.strip.downcase ? true : false)
+    end
+    true
+  end
+
   # @param spec [Gem::Specification] plugin gem specification
   # @return [Boolean] true if this spec is for an installable logstash plugin
   def self.logstash_plugin_gem_spec?(spec)

spec/pluginmanager/util_spec.rb

@@ -0,0 +1,42 @@
+# encoding: utf-8
+require "spec_helper"
+require "pluginmanager/util"
+require "gems"
+
+describe LogStash::PluginManager do
+
+  let(:plugin_name) { "logstash-output-elasticsearch" }
+
+  let(:version_data) do
+    [ { "authors"=>"Elastic", "built_at"=>"2015-08-11T00:00:00.000Z", "description"=>"Output events to elasticsearch",
+        "downloads_count"=>1638, "metadata"=>{"logstash_group"=>"output", "logstash_plugin"=>"true"}, "number"=>"2.0.0.pre",
+        "summary"=>"Logstash Output to Elasticsearch", "platform"=>"java", "ruby_version"=>">= 0", "prerelease"=>true,
+        "licenses"=>["apache-2.0"], "requirements"=>[], "sha"=>"194b27099c13605a882a3669e2363fdecccaab1de48dd44b0cda648dd5516799"},
+    { "authors"=>"Elastic", "built_at"=>"2015-08-10T00:00:00.000Z", "description"=>"Output events to elasticsearch",
+      "downloads_count"=>1638, "metadata"=>{"logstash_group"=>"output", "logstash_plugin"=>"true"}, "number"=>"1.0.7",
+      "summary"=>"Logstash Output to Elasticsearch", "platform"=>"java", "ruby_version"=>">= 0", "prerelease"=>false,
+      "licenses"=>["apache-2.0"], "requirements"=>[], "sha"=>"194b27099c13605a882a3669e2363fdecccaab1de48dd44b0cda648dd5516799"},
+    { "authors"=>"Elastic", "built_at"=>"2015-08-09T00:00:00.000Z", "description"=>"Output events to elasticsearch",
+      "downloads_count"=>1638, "metadata"=>{"logstash_group"=>"output", "logstash_plugin"=>"true"}, "number"=>"1.0.4",
+      "summary"=>"Logstash Output to Elasticsearch", "platform"=>"java", "ruby_version"=>">= 0", "prerelease"=>false,
+      "licenses"=>["apache-2.0"], "requirements"=>[], "sha"=>"194b27099c13605a882a3669e2363fdecccaab1de48dd44b0cda648dd5516799"} ]
+  end
+
+  before(:each) do
+    allow(Gems).to receive(:versions).with(plugin_name).and_return(version_data)
+  end
+
+  context "fetch plugin info" do
+
+    it "should search for the last version infomation non prerelease" do
+      version_info = LogStash::PluginManager.fetch_latest_version_info(plugin_name)
+      expect(version_info["number"]).to eq("1.0.7")
+    end
+
+
+    it "should search for the last version infomation with prerelease" do
+      version_info = LogStash::PluginManager.fetch_latest_version_info(plugin_name, :pre => true)
+      expect(version_info["number"]).to eq("2.0.0.pre")
+    end
+  end
+end