Heroku で DNS の Aレコードで Heroku のレガシーな IP アドレスを指定するルーティングの方法が 2014/09/22 で廃止されるそうです。example.com のようなネイキッドドメインを Heroku で使うにはひと工夫しないといけなくなりました。

CDN サービス「CloudFlare」を使うと CNAME flattening を実現できるそうなので、詳しくは下記の記事を参考に対応したいと思います。

・妻のパン屋のwebサイトをいろいろ更新した話 ～Rails 4アップデートとかサイトの高速化とか～ - give IT a try

以下、Heroku からの「Action Required: Legacy Routing End of Life」お知らせメールです。

heroku Hi there,

This is a reminder that Heroku is turning off the legacy “.heroku.com” routing path on September 22nd 2014. This is part of an effort to to standardize on a single, fast, highly available and scalable routing stack for all customers.

You are receiving this email because one or more of your apps is still using the legacy routing and you must take action to ensure continued operation of those apps after the September 22nd deadline.

The following domains which are still receiving legacy traffic are:

example.com

Also, you may use the Legacy Routing Analyzer to see which of your apps are affected. Login to your Heroku account and click here.

We recommend that you migrate those affected apps away from the legacy routing infrastructure as soon as possible.

For instructions on how to make the move, please visit this Heroku Dev Center article.

We know that changing DNS settings for live apps requires care and planning, and we will assist with guidance and advice for you to make the necessary updates. If you have any questions about this topic, feel free to open a support ticket.

We will continue to send reminders in the coming months to owners and collaborators on apps that continue to use the legacy routing infrastructure.

Cheers, Heroku team