Rails bootsnap/eventmachine in boot.rb NoMethodError get_hosts_path for module Win32::Resolv

Question

Running Rails under Windows with this in config/boot.rb: require 'bootsnap/setup'

Results in

ruby33/lib/ruby/3.3.0/gems/eventmachine-1.2.7/lib/em/resolver.rb:14:in <class:Resolver>': undefined method get_hosts_path' for module Win32::Resolv (NoMethodError)

Answer 1

To solve this particular issue, add the following code to config/boot.rb prior to bootsnap:

if Gem.win_platform?
  require 'win32/resolv'
end

This require ensures that the Win32::Resolv module, and the get_hosts_path method, is available to EventMachine when it is referenced within Bootsnap.

An example of config/boot.rb with Bootsnap implemented according to Bootsnap, including BootLib, as described by Bootsnap and its reference to BootLib (This assumes that the BootLib module exists in lib/core_ext/, and includes Bumbler, YMMV):

require 'rubygems'
require_relative '../lib/core_ext/boot_lib'
if Gem.win_platform?
  require 'win32/resolv'
end
ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../../Gemfile', __FILE__)
ENV['BUNDLER_LOAD_BUMBLER_ON_STARTUP'] = 'true'
require 'bundler/setup' if File.exist?(ENV['BUNDLE_GEMFILE'])
# require 'bootsnap/setup' # Speed up boot time by caching expensive operations.
BootLib::Require.from_gem('bootsnap', 'bootsnap')
env = ENV['RAILS_ENV'] || "development"
Bootsnap.setup(
  cache_dir: 'tmp/cache', # Path to your cache
  ignore_directories: ['node_modules'], # Directory names to skip.
  development_mode: env == 'development', # Current working environment, e.g. RACK_ENV, RAILS_ENV, etc
  load_path_cache: true, # Optimize the LOAD_PATH with a cache
  compile_cache_iseq: true, # Compile Ruby code into ISeq cache, breaks coverage reporting.
  compile_cache_yaml: true, # Compile YAML into a cache
  compile_cache_json: true, # Compile JSON into a cache
  readonly: true, # Use the caches but don't update them on miss or stale entries.
)