`bundle install`に失敗する（windows/Ubuntsu/docker）

# 概要
* 以下の開発環境で開発を進めており、ジェムの `rails-i18n` を導入しようとした
    * Windows11
        * Ubuntsu
            * docker
                * Rails7.2.1

# `bundle install` でエラーになる
```bash:確認したエラー
rails@XXXXXXXXXXX:/myapp$ bundle install
Fetching gem metadata from https://rubygems.org/.........
Resolving dependencies...
Fetching rails-i18n 7.0.9

Retrying download gem from https://rubygems.org/ due to error (2/4): Bundler::PermissionError There was an error while trying to write to `/usr/local/bundle/cache/rails-i18n-7.0.9.gem`. It is likely that you need to grant write permissions for that path.

Retrying download gem from https://rubygems.org/ due to error (3/4): Bundler::PermissionError There was an error while trying to write to `/usr/local/bundle/cache/rails-i18n-7.0.9.gem`. It is likely that you need to grant write permissions for that path.

Retrying download gem from https://rubygems.org/ due to error (4/4): Bundler::PermissionError There was an error while trying to write to `/usr/local/bundle/cache/rails-i18n-7.0.9.gem`. It is likely that you need to grant write permissions for that path.

Bundler::PermissionError: There was an error while trying to write to
`/usr/local/bundle/cache/rails-i18n-7.0.9.gem`. It is likely that you need to grant write permissions
for that path.
  /usr/local/bundle/gems/bundler-2.5.19/lib/bundler/shared_helpers.rb:107:in `rescue in
filesystem_access'
  /usr/local/bundle/gems/bundler-2.5.19/lib/bundler/shared_helpers.rb:104:in `filesystem_access'
/usr/local/bundle/gems/bundler-2.5.19/lib/bundler/rubygems_integration.rb:445:in `block in
download_gem'
  /usr/local/bundle/gems/bundler-2.5.19/lib/bundler/retry.rb:40:in `run'
  /usr/local/bundle/gems/bundler-2.5.19/lib/bundler/retry.rb:30:in `attempt'
  /usr/local/bundle/gems/bundler-2.5.19/lib/bundler/rubygems_integration.rb:437:in `download_gem'
  /usr/local/bundle/gems/bundler-2.5.19/lib/bundler/source/rubygems.rb:482:in `download_gem'
  /usr/local/bundle/gems/bundler-2.5.19/lib/bundler/source/rubygems.rb:439:in `fetch_gem'
  /usr/local/bundle/gems/bundler-2.5.19/lib/bundler/source/rubygems.rb:423:in `fetch_gem_if_possible'
  /usr/local/bundle/gems/bundler-2.5.19/lib/bundler/source/rubygems.rb:162:in `install'
  /usr/local/bundle/gems/bundler-2.5.19/lib/bundler/installer/gem_installer.rb:55:in `install'
/usr/local/bundle/gems/bundler-2.5.19/lib/bundler/installer/gem_installer.rb:17:in
`install_from_spec'
  /usr/local/bundle/gems/bundler-2.5.19/lib/bundler/installer/parallel_installer.rb:133:in `do_install'
/usr/local/bundle/gems/bundler-2.5.19/lib/bundler/installer/parallel_installer.rb:124:in `block in
worker_pool'
  /usr/local/bundle/gems/bundler-2.5.19/lib/bundler/worker.rb:62:in `apply_func'
  /usr/local/bundle/gems/bundler-2.5.19/lib/bundler/worker.rb:57:in `block in process_queue'
  /usr/local/bundle/gems/bundler-2.5.19/lib/bundler/worker.rb:54:in `loop'
  /usr/local/bundle/gems/bundler-2.5.19/lib/bundler/worker.rb:54:in `process_queue'
/usr/local/bundle/gems/bundler-2.5.19/lib/bundler/worker.rb:90:in `block (2 levels) in
create_threads'

An error occurred while installing rails-i18n (7.0.9), and Bundler cannot continue.

In Gemfile:
  rails-i18n
```

## エラー文にあたりをつける
* とりあえずは原因らしき文言を見つけて解決を目指すこととした
    * 以下の文言より「書き込みの権限が無い」という旨であることを把握したのでさらに調査を進めた
```bash:原因らしき文言
Bundler::PermissionError: There was an error while trying to write to
`/usr/local/bundle/cache/rails-i18n-7.0.9.gem`. It is likely that you need to grant write permissions
for that path.
```

# シンプルに管理者権限では無かっただけだった
エラー文にもあった `/usr/local/bundle/cache/` までのフォルダーおよびファイルの所有者や権限を調べていて `root` であることに気づいた

* 以下のように `root` ユーザーで実行していなかったからではと考えた (`rails`ユーザーだったの原因)
```
rails@XXXXXXXXXXX:/myapp$ bundle install
```

## `root` ユーザーで実行
* コンテナにアクセスする際 `root` ユーザーでアクセスするようにコマンドを見直した
```:今まで
docker compose exec web bash
```

```:root ユーザーとして
docker compose exec -it -u root web bash
```

### 実行結果
* 結果として問題なく導入することが出来た

```bash:実行結果
root@XXXXXXXXXXX:/myapp# bundle install
Fetching gem metadata from https://rubygems.org/.........
Resolving dependencies...
Fetching rails-i18n 7.0.9
Installing rails-i18n 7.0.9
Bundle complete! 22 Gemfile dependencies, 110 gems now installed.
Use `bundle info [gemname]` to see where a bundled gem is installed.
```

---
### 参考資料・参考記事
https://qiita.com/susumu_chang/items/956435e9baa91774a966

https://qiita.com/yonai_shun/items/9907e056480b053dc420