Jekyll Requires Webrick Gem on Ruby 3.0

Overview

Jekyll on Ruby 3.0 requires the webrick gem to be added to the Gemfile. If the site doesn’t, Jekyll will fail to generate and serve the site. Below is the error that I’m discussing.

bundle exec jekyll serve
Configuration file: /home/example/testing/myblog/_config.yml
            Source: /home/example/testing/myblog
       Destination: /home/example/testing/myblog/_site
 Incremental build: disabled. Enable with --incremental
      Generating...
       Jekyll Feed: Generating feed for posts
                    done in 0.844 seconds.
  Please add the following to your Gemfile to avoid polling for changes:
    require 'rbconfig'
    if RbConfig::CONFIG['target_os'] =~ /(?i-mx:bsd|dragonfly)/
      gem 'rb-kqueue', '>= 0.2'
    end
 Auto-regeneration: enabled for '/home/example/testing/myblog'
                    ------------------------------------------------
      Jekyll 4.2.1   Please append `--trace` to the `serve` command
                     for any additional information or backtrace.
                    ------------------------------------------------
/home/example/.gems/ruby/3.0/gems/ruby/3.0/gems/jekyll-4.2.1/lib/jekyll/commands/serve/servlet.rb:3:in `require': cannot load such file -- webrick (LoadError)
        from /home/example/.gems/ruby/3.0/gems/ruby/3.0/gems/jekyll-4.2.1/lib/jekyll/commands/serve/servlet.rb:3:in `<top (required)>'
        from /home/example/.gems/ruby/3.0/gems/ruby/3.0/gems/jekyll-4.2.1/lib/jekyll/commands/serve.rb:179:in `require_relative'
        from /home/example/.gems/ruby/3.0/gems/ruby/3.0/gems/jekyll-4.2.1/lib/jekyll/commands/serve.rb:179:in `setup'
        from /home/example/.gems/ruby/3.0/gems/ruby/3.0/gems/jekyll-4.2.1/lib/jekyll/commands/serve.rb:100:in `process'
        from /home/example/.gems/ruby/3.0/gems/ruby/3.0/gems/jekyll-4.2.1/lib/jekyll/command.rb:91:in `block in process_with_graceful_fail'
        from /home/example/.gems/ruby/3.0/gems/ruby/3.0/gems/jekyll-4.2.1/lib/jekyll/command.rb:91:in `each'
        from /home/example/.gems/ruby/3.0/gems/ruby/3.0/gems/jekyll-4.2.1/lib/jekyll/command.rb:91:in `process_with_graceful_fail'
        from /home/example/.gems/ruby/3.0/gems/ruby/3.0/gems/jekyll-4.2.1/lib/jekyll/commands/serve.rb:86:in `block (2 levels) in init_with_program'
        from /home/example/.gems/ruby/3.0/gems/ruby/3.0/gems/mercenary-0.4.0/lib/mercenary/command.rb:221:in `block in execute'
        from /home/example/.gems/ruby/3.0/gems/ruby/3.0/gems/mercenary-0.4.0/lib/mercenary/command.rb:221:in `each'
        from /home/example/.gems/ruby/3.0/gems/ruby/3.0/gems/mercenary-0.4.0/lib/mercenary/command.rb:221:in `execute'
        from /home/example/.gems/ruby/3.0/gems/ruby/3.0/gems/mercenary-0.4.0/lib/mercenary/program.rb:44:in `go'
        from /home/example/.gems/ruby/3.0/gems/ruby/3.0/gems/mercenary-0.4.0/lib/mercenary.rb:21:in `program'
        from /home/example/.gems/ruby/3.0/gems/ruby/3.0/gems/jekyll-4.2.1/exe/jekyll:15:in `<top (required)>'
        from /home/example/.gems/ruby/3.0/gems/ruby/3.0/bin/jekyll:25:in `load'
        from /home/example/.gems/ruby/3.0/gems/ruby/3.0/bin/jekyll:25:in `<main>'

Solution

To fix this the webrick gem needs to be installed. This can be done by entering the following command.

bundle add webrick

Below is the output from the command.

Fetching gem metadata from https://rubygems.org/.........
Resolving dependencies...
Fetching gem metadata from https://rubygems.org/.........
Resolving dependencies...
Using public_suffix 4.0.6
Using bundler 2.2.33
Using concurrent-ruby 1.1.9
Using http_parser.rb 0.8.0
Using eventmachine 1.2.7
Using ffi 1.15.4
Using rexml 3.2.5
Using liquid 4.0.3
Using colorator 1.1.0
Using mercenary 0.4.0
Using rouge 3.27.0
Using safe_yaml 1.0.5
Using forwardable-extended 2.6.0
Using unicode-display_width 1.8.0
Using em-websocket 0.5.3
Using addressable 2.8.0
Using sassc 2.4.0
Using rb-inotify 0.10.1
Using rb-fsevent 0.11.0
Using i18n 1.8.11
Using webrick 1.7.0
Using pathutil 0.16.2
Using kramdown 2.3.1
Using terminal-table 2.0.0
Using jekyll-sass-converter 2.1.0
Using listen 3.7.0
Using kramdown-parser-gfm 1.1.0
Using jekyll-watch 2.2.1
Using jekyll 4.2.1
Using jekyll-feed 0.15.1
Using jekyll-seo-tag 2.7.1
Using minima 2.5.1

Once you start the site, it will have the output below. If ther aren’t any errors, it’s working as expected.

Configuration file: /home/example/testing/myblog/_config.yml
            Source: /home/example/testing/myblog
       Destination: /home/example/testing/myblog/_site
 Incremental build: disabled. Enable with --incremental
      Generating...
       Jekyll Feed: Generating feed for posts
                    done in 2.179 seconds.
  Please add the following to your Gemfile to avoid polling for changes:
    require 'rbconfig'
    if RbConfig::CONFIG['target_os'] =~ /(?i-mx:bsd|dragonfly)/
      gem 'rb-kqueue', '>= 0.2'
    end
 Auto-regeneration: enabled for '/home/example/testing/myblog'
    Server address: http://127.0.0.1:4000/
  Server running... press ctrl-c to stop.