add a check for a plugin to be in rubygems before going to install it

make sure dependency gems is installed

cleanup unnecessary code

Fixes #3021

rakelib/default_plugins.rb

@@ -146,10 +146,16 @@ module LogStash
     # @return [Array<String>] list of all plugin names as defined in the logstash-plugins github organization, minus names that matches the ALL_PLUGINS_SKIP_LIST
     def self.fetch_all_plugins
       require 'octokit'
-
       Octokit.auto_paginate = true
       repos = Octokit.organization_repositories("logstash-plugins")
-      repos.map(&:name).reject{|name| name =~ ALL_PLUGINS_SKIP_LIST}
+      repos.map(&:name).reject do |name|
+        name =~ ALL_PLUGINS_SKIP_LIST || !is_released?(name)
+      end
+    end
+
+    def self.is_released?(plugin)
+      require 'gems'
+      !Gems.search(plugin).empty?
     end
   end
 end

rakelib/dependency.rake

@@ -29,4 +29,8 @@ namespace "dependency" do
     Rake::Task["gem:require"].invoke("octokit", ">= 0", LogStash::Environment.logstash_gem_home)
   end # task octokit
 
+  task "gems" do
+    Rake::Task["gem:require"].invoke("gems", ">= 0", LogStash::Environment.logstash_gem_home)
+  end # task gems
+
 end # namespace dependency

rakelib/plugin.rake

@@ -50,7 +50,7 @@ namespace "plugin" do
     task.reenable # Allow this task to be run again
   end
 
-  task "install-all" => [ "dependency:octokit" ] do
+  task "install-all" => [ "dependency:octokit", "dependency:gems" ] do
     puts("[plugin:install-all] Installing all plugins from https://github.com/logstash-plugins")
     install_plugins("--no-verify", *LogStash::RakeLib.fetch_all_plugins)