@Naf お知らせありがとうございます! jwtの新しいのがいかんかったみたいです
https://github.com/tootsuite/mastodon/pull/4958#issuecomment-329862328
github.comBump ruby version to 2.4.2 by zunda · Pull Request #4958 · tootsuite/mastodonhttps://www.ruby-lang.org/en/news/2017/09/14/ruby-2-4-2-released/
Gemfile.lock is also updated.
TODO
Update Dockerfile with Alpine release of ruby-2.4.2