Docker for Mac OSXを使ってJekyllをいじっているのですが。ファイルを編集すると次のようなエラーが…

server    |       Regenerating: 1 file(s) changed at 2016-09-26 14:48:17 E, [2016-09-26T14:48:21.007586 #6] ERROR -- : run() in thread failed: invalid byte sequence in US-ASCII:\n /usr/local/lib/ruby/2.3.0/pathname.rb:41:in `=~'
server    | /usr/local/lib/ruby/2.3.0/pathname.rb:41:in `chop_basename'
server    | /usr/local/lib/ruby/2.3.0/pathname.rb:358:in `plus'
server    | /usr/local/lib/ruby/2.3.0/pathname.rb:350:in `+'
server    | /usr/local/bundle/gems/listen-3.0.8/lib/listen/adapter/linux.rb:47:in `_process_event'
server    | /usr/local/bundle/gems/listen-3.0.8/lib/listen/adapter/base.rb:42:in `block (2 levels) in configure'
server    | /usr/local/bundle/gems/rb-inotify-0.9.7/lib/rb-inotify/notifier.rb:205:in `block in watch'
server    | /usr/local/bundle/gems/rb-inotify-0.9.7/lib/rb-inotify/watcher.rb:41:in `callback!'
server    | /usr/local/bundle/gems/rb-inotify-0.9.7/lib/rb-inotify/event.rb:128:in `callback!'
server    | /usr/local/bundle/gems/rb-inotify-0.9.7/lib/rb-inotify/notifier.rb:238:in `block in process'
server    | /usr/local/bundle/gems/rb-inotify-0.9.7/lib/rb-inotify/notifier.rb:238:in `each'
server    | /usr/local/bundle/gems/rb-inotify-0.9.7/lib/rb-inotify/notifier.rb:238:in `process'
server    | /usr/local/bundle/gems/rb-inotify-0.9.7/lib/rb-inotify/notifier.rb:221:in `run'
server    | /usr/local/bundle/gems/listen-3.0.8/lib/listen/adapter/linux.rb:39:in `_run'

生成されるファイル名が日本語だとエラーになります。

色々調べた結果、RubyがUS-ASCIIになっているのが原因でした（via dockerでpuppet実行エラー (invalid byte sequence in US-ASCII) - Qiita）。

docker-compose.yaml に下記を追加して解決。

environment:
  RUBYOPT: "-EUTF-8"