Backport PR #14175 to 8.3: Refactor: avoid loading polyglot

[github-actions]

Backport PR #14175 to 8.3 branch, original message:

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Release notes

[rn:skip]

What does this PR do?

Avoids require 'polyglot' (and a few others) which patches Kernel.require, for which we introduced another patch due JRuby 9.3 in #14114 (targeted for LS 8.3).

Why is it important/What is the impact to the user?

No user impact.

With this patch in place logstash-core in tests no longer loads polyglot gem (which patches Kernel.require and thus leads to a circular error issue - same as observed in #14114) and is easier to test against JRuby 9.3 (outside Docker).

Sample failure:

An error occurred while loading ./spec/inputs/http_poller_spec.rb.
Failure/Error: require "logstash/devutils/rspec/spec_helper"

RuntimeError:
  circular causes
# /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/polyglot-0.3.5/lib/polyglot.rb:73:in `require'
# /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/faraday-1.10.0/lib/faraday/dependency_loader.rb:11:in `dependency'
# /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/faraday-excon-1.1.0/lib/faraday/adapter/excon.rb:7:in `<class:Excon>'
# /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/faraday-excon-1.1.0/lib/faraday/adapter/excon.rb:6:in `<class:Adapter>'
# /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/faraday-excon-1.1.0/lib/faraday/adapter/excon.rb:4:in `<module:Faraday>'
# /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/faraday-excon-1.1.0/lib/faraday/adapter/excon.rb:3:in `<main>'
# /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/faraday-excon-1.1.0/lib/faraday/excon.rb:3:in `<main>'
# /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/polyglot-0.3.5/lib/polyglot.rb:65:in `require'
# /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/faraday-1.10.0/lib/faraday.rb:40:in `<main>'
# /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/polyglot-0.3.5/lib/polyglot.rb:65:in `require'
# /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/elasticsearch-transport-7.17.1/lib/elasticsearch/transport.rb:23:in `<main>'
# /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/polyglot-0.3.5/lib/polyglot.rb:65:in `require'
# /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/elasticsearch-7.17.1/lib/elasticsearch.rb:19:in `<main>'
# /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/polyglot-0.3.5/lib/polyglot.rb:65:in `require'
# /home/kares/workspace/work/elastic/logstash-7.16.3/logstash-core/lib/logstash/elasticsearch_client.rb:18:in `<main>'
# /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/polyglot-0.3.5/lib/polyglot.rb:65:in `require'
# /home/kares/workspace/work/elastic/logstash-7.16.3/logstash-core/lib/logstash/config/modules_common.rb:18:in `<main>'
# /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/polyglot-0.3.5/lib/polyglot.rb:65:in `require'
# /home/kares/workspace/work/elastic/logstash-7.16.3/logstash-core/lib/logstash/config/source/modules.rb:19:in `<main>'
# /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/polyglot-0.3.5/lib/polyglot.rb:65:in `require'
# /home/kares/workspace/work/elastic/logstash-7.16.3/logstash-core/lib/logstash/config/source_loader.rb:19:in `<main>'
# /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/polyglot-0.3.5/lib/polyglot.rb:65:in `require'
# /home/kares/workspace/work/elastic/logstash-7.16.3/logstash-core/lib/logstash/agent.rb:24:in `<main>'
# /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/logstash-devutils-2.3.0-java/lib/logstash/devutils/rspec/logstash_helpers.rb:1:in `<main>'
# /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/logstash-devutils-2.3.0-java/lib/logstash/devutils/rspec/spec_helper.rb:17:in `<main>'

---

Tested with a sample plugin doing a runtime require (just to demonstrate Polyglot is no longer being loaded during plugin's tests):

        begin
          require 'foo.rb'
        rescue LoadError => e
          puts e.inspect
          puts '  ' + e.backtrace.join("\n  ")
        end

WITHOUT this patch (polyglot is still involved with require):

#<Polyglot::PolyglotLoadError: Failed to load foo.rb using extensions rb, treetop, tt>
  /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/polyglot-0.3.5/lib/polyglot.rb:55:in `load'
  /opt/local/rvm/gems/jruby-9.3.4.0@ls/gems/polyglot-0.3.5/lib/polyglot.rb:68:in `require'
  /home/kares/workspace/work/elastic/logstash/logstash-core/lib/logstash/patches/polyglot.rb:9:in `require'
  /home/kares/workspace/work/elastic/plugins/logstash-input-elasticsearch/spec/inputs/elasticsearch_spec.rb:42:in `block in <main>'
  org/jruby/RubyBasicObject.java:2673:in `instance_exec'

WITH a patched LS :

#<LoadError: no such file to load -- foo.rb>
  org/jruby/RubyKernel.java:1017:in `require'
  /home/kares/workspace/work/elastic/plugins/logstash-input-elasticsearch/spec/inputs/elasticsearch_spec.rb:42:in `block in <main>'
  org/jruby/RubyBasicObject.java:2673:in `instance_exec'

Checklist

Integration tests are currently failing due missing SNAPSHOT builds.
Here's the same change set (+ #14184) against 8.3 #14182 🟢

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files (and/or docker env variables)
• I have added tests that prove my fix is effective or that my feature works