Could not fetch specs from https://rubygems.org/と言われてbundle installができない。

Question

前提・実現したいこと

bundle installしたい。

発生している問題・エラーメッセージ

$ bundle install
Your Gemfile lists the gem pg (= 1.1.4) more than once.
You should probably keep only one of them.
Remove any duplicate entries and specify the gem only once.
While it's not a problem now, it could cause errors if you change the version of one of them later.
Fetching source index from https://rubygems.org/

Retrying fetcher due to error (2/4): Bundler::HTTPError Could not fetch specs from https://rubygems.org/ due to underlying error <Net::OpenTimeout: execution expired (https://rubygems.org/specs.4.8.gz)>

Retrying fetcher due to error (3/4): Bundler::HTTPError Could not fetch specs from https://rubygems.org/ due to underlying error <Net::OpenTimeout: execution expired (https://rubygems.org/specs.4.8.gz)>

Retrying fetcher due to error (4/4): Bundler::HTTPError Could not fetch specs from https://rubygems.org/ due to underlying error <Net::OpenTimeout: execution expired (https://rubygems.org/specs.4.8.gz)>

Could not fetch specs from https://rubygems.org/ due to underlying error <Net::OpenTimeout: execution expired (https://rubygems.org/specs.4.8.gz)>

該当のソースコード

source 'https://rubygems.org'
git_source(:github) { |repo| "https://github.com/#{repo}.git" }

ruby '2.7.1'

# Bundle edge Rails instead: gem 'rails', github: 'rails/rails', branch: 'main'
gem 'rails', '~> 6.1.4', '>= 6.1.4.1'
# Use Puma as the app server
gem 'puma', '~> 5.0'
# Use SCSS for stylesheets
gem 'sass-rails', '>= 6'
# Transpile app-like JavaScript. Read more: https://github.com/rails/webpacker
gem 'webpacker', '~> 5.0'
# Turbolinks makes navigating your web application faster. Read more: https://github.com/turbolinks/turbolinks
gem 'turbolinks', '~> 5'
# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
gem 'jbuilder', '~> 2.7'
# Use Redis adapter to run Action Cable in production
# gem 'redis', '~> 4.0'
# Use Active Model has_secure_password
# gem 'bcrypt', '~> 3.1.7'

# Use Active Storage variant
# gem 'image_processing', '~> 1.2'

# Reduces boot times through caching; required in config/boot.rb
gem 'bootsnap', '>= 1.4.4', require: false

group :development, :test do
  # Call 'byebug' anywhere in the code to stop execution and get a debugger console
  gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
  gem 'pg', '1.1.4'
end

group :development do
  # Access an interactive console on exception pages or by calling 'console' anywhere in the code.
  gem 'web-console', '>= 4.1.0'
  # Display performance information such as SQL time and flame graphs for each request in your browser.
  # Can be configured to work on production as well see: https://github.com/MiniProfiler/rack-mini-profiler/blob/master/README.md
  gem 'rack-mini-profiler', '~> 2.0'
  gem 'listen', '~> 3.3'
  # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
  gem 'spring'
end

group :test do
  # Adds support for Capybara system testing and selenium driver
  gem 'capybara', '>= 3.26'
  gem 'selenium-webdriver'
  # Easy installation and use of web drivers to run system tests with browsers
  gem 'webdrivers'
end

group :production do
  gem 'pg', '1.1.4'
end
# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]

gem 'bootstrap'
gem 'dotenv-rails'

試したこと

• wgetでリクエストを投げて確認してみるとIPv6の場合だけ接続に失敗することを確認した。

$ wget https://rubygems.org/specs.4.8.gz
--2021-09-30 04:59:18--  https://rubygems.org/specs.4.8.gz
Resolving rubygems.org (rubygems.org)... 2a04:4e42:200::483, 2a04:4e42::483, 2a04:4e42:400::483, ...
Connecting to rubygems.org (rubygems.org)|2a04:4e42:200::483|:443... failed: Operation timed out.
Connecting to rubygems.org (rubygems.org)|2a04:4e42::483|:443... failed: Operation timed out.
Connecting to rubygems.org (rubygems.org)|2a04:4e42:400::483|:443... failed: Operation timed out.
Connecting to rubygems.org (rubygems.org)|2a04:4e42:600::483|:443... failed: Operation timed out.
Connecting to rubygems.org (rubygems.org)|151.101.193.227|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 4485268 (4.3M) [application/octet-stream]
Saving to: ‘specs.4.8.gz.1’

• gem cannot access rubygems.orgには以下のことが書いてありました。

api.rubygems.org is currently experiencing issues with IPv6 setup: this hostname has 4 IPv6 addresses, but responds on neither of them. Neither to ping, nor to TCP connection attempts. "When you are running gem, your gem tries IPv6 addresses first and times out on them, not having time to even try IPv4 addresses.

The solution is to lower priority of IPv6 addresses for api.rubygems.org, so that gem will try IPv4 addresses first. In order to do it, put these lines into /etc/gai.conf:

• 以上のことから、sudo vi /etc/gai.confで、以下を記述しましたが変わりがなかったです。

# Debian defaults.
precedence  ::1/128         50
precedence  ::/0            40
precedence  2002::/16       30
precedence  ::/96           20
precedence  ::ffff:0:0/96   10

# Low precedence for api.rubygems.org IPv6 addresses.
precedence  2a04:4e42::0/32  5

• rubygems.orgのIPv4アドレスを調べてhostsに記載もしてみましたが変わらなかったです。

$ host rubygems.org
rubygems.org has address 151.101.193.227
rubygems.org has address 151.101.129.227
rubygems.org has address 151.101.65.227
rubygems.org has address 151.101.1.227
rubygems.org has IPv6 address 2a04:4e42:600::483
rubygems.org has IPv6 address 2a04:4e42::483
rubygems.org has IPv6 address 2a04:4e42:200::483
rubygems.org has IPv6 address 2a04:4e42:400::483
rubygems.org mail is handled by 10 mxb.mailgun.org.
rubygems.org mail is handled by 10 mxa.mailgun.org.

$ sudo vi /etc/hosts
##
# Host Database
#
# localhost is used to configure the loopback interface
# when the system is booting.  Do not change this entry.
##	127.0.0.1       localhost
255.255.255.255 broadcasthost	::1             localhost
	
/* 記述*/
151.101.129.227  rubygems.org
151.101.65.227   rubygems.org
151.101.1.227    rubygems.org
151.101.193.227  rubygems.org

• 以上のことをしても、変わりはなかったので、gem update --systemしてみたところ、以下のようなエラーが出ました。

$ gem update --system
ERROR:  While executing gem ... (Gem::RemoteFetcher::FetchError)
    Net::OpenTimeout: execution expired (https://rubygems.org/specs.4.8.gz)

参考

• rails5.2 bundle installがこけるので原因を調査してみた - Qiita
• gem cannot access rubygems.org
• rubygems.orgにアクセスできなくなった場合の解決法

手詰まりになってわからなくなってしまいました。
よろしくお願いします。

補足情報（FW/ツールのバージョンなど）

• ruby 2.7.1
• Rails 6.1.4.1
• Bundler v2.2.24

Answer 1

/etc/hostsに設定した後に上のwgetのコマンドの結果は最初から変わりないですか？

自分の環境で以下の手順で試しました。

1. /etc/hostsへ追加

151.101.193.227  rubygems.org

2. wgetで試す、Resolvingの後ろが設定するIPへ変わる

wget "https://rubygems.org/specs.4.8.gz"
--2021-10-19 15:44:24--  https://rubygems.org/specs.4.8.gz
Resolving rubygems.org (rubygems.org)... 151.101.193.227
Connecting to rubygems.org (rubygems.org)|151.101.193.227|:443... connected.