Refactor: revisit logstash bootstraping bits (#13791)

* Refactor: logstash boot to know what to do
* Refactor: reduce LOAD_PATH - load jars directly
* Refactor: unused requires in runner
* Refactor: boot - require libs when to be used

lib/bootstrap/bundler.rb

@@ -15,10 +15,6 @@
 # specific language governing permissions and limitations
 # under the License.
 
-require "fileutils"
-require "stringio"
-require 'set'
-
 module LogStash
   module Bundler
     extend self
@@ -115,6 +111,7 @@ module LogStash
       require "bundler"
       require "bundler/cli"
 
+      require "fileutils"
       # create Gemfile from template iff it does not exist
       unless ::File.exists?(Environment::GEMFILE_PATH)
         FileUtils.copy(
@@ -213,7 +210,7 @@ module LogStash
 
     # @param plugin_names [Array] logstash plugin names that are going to update
     # @return [Array] gem names that plugins depend on, including logstash plugins
-    def expand_logstash_mixin_dependencies(plugin_names)
+    def expand_logstash_mixin_dependencies(plugin_names); require 'set'
       plugin_names = Array(plugin_names) if plugin_names.is_a?(String)
 
       # get gem names in Gemfile.lock. If file doesn't exist, it will be generated
@@ -299,7 +296,7 @@ module LogStash
     # capture any $stdout from the passed block. also trap any exception in that block, in which case the trapped exception will be returned
     # @param [Proc] the code block to execute
     # @return [String, Exception] the captured $stdout string and any trapped exception or nil if none
-    def capture_stdout(&block)
+    def capture_stdout(&block); require 'stringio'
       old_stdout = $stdout
       $stdout = StringIO.new("", "w")
       begin

lib/bootstrap/environment.rb

@@ -76,10 +76,7 @@ module LogStash
   end
 end
 
-# when launched as a script, not require'd, (currently from bin/logstash and bin/logstash-plugin) the first
-# argument is the path of a Ruby file to require and a LogStash::Runner class is expected to be
-# defined and exposing the LogStash::Runner#main instance method which will be called with the current ARGV
-# currently lib/logstash/runner.rb and lib/pluginmanager/main.rb are called using this.
+# when launched as a script, not require'd, (currently from bin/logstash)
 if $0 == __FILE__
   bundler_options = {:without => [:build, :development]}
   ## Check for dev flags - this needs to be done before the runner is invoked to set bundler options
@@ -89,7 +86,7 @@ if $0 == __FILE__
   LogStash::Bundler.setup!(bundler_options)
   require_relative "patches/jar_dependencies"
 
-  require ARGV.shift
+  require 'logstash/runner'
   exit_status = LogStash::Runner.run("bin/logstash", ARGV)
   exit(exit_status || 0)
 end

logstash-core/lib/logstash-core/logstash-core.rb

@@ -23,9 +23,8 @@ require "java"
 # wrapper.
 unless $LS_JARS_LOADED
   jar_path = File.join(File.dirname(File.dirname(__FILE__)), "jars")
-  $:.unshift jar_path
-  Dir.glob(jar_path + '/*.jar') do |jar|
-    require File.basename(jar)
+  Dir.glob("#{jar_path}/*.jar") do |jar|
+    load jar
   end
   java_import org.logstash.RubyUtil
 end

logstash-core/lib/logstash/runner.rb

@@ -32,7 +32,6 @@ if !LogStash::OSS
 end
 
 require "clamp"
-require "net/http"
 
 require "logstash-core/logstash-core"
 require "logstash/environment"
@@ -50,7 +49,6 @@ require 'logstash/plugins'
 require "logstash/modules/util"
 require "logstash/bootstrap_check/default_config"
 require "logstash/bootstrap_check/persisted_queue_config"
-require "set"
 require 'logstash/deprecation_message'
 
 java_import 'org.logstash.FileLockFactory'

logstash-core/src/main/java/org/logstash/Logstash.java

@@ -241,10 +241,9 @@ public final class Logstash implements Runnable, AutoCloseable {
      * @return RubyInstanceConfig
      */
     private static RubyInstanceConfig buildConfig(final Path home, final String[] args) {
-        final String[] arguments = new String[args.length + 2];
-        System.arraycopy(args, 0, arguments, 2, args.length);
+        final String[] arguments = new String[args.length + 1];
+        System.arraycopy(args, 0, arguments, 1, args.length);
         arguments[0] = safePath(home, "lib", "bootstrap", "environment.rb");
-        arguments[1] = safePath(home, "logstash-core", "lib", "logstash", "runner.rb");
         return initRubyConfig(home, arguments);
     }