TODO:
| Middleware | Environment Variable |
|---|---|
| Redis | REDIS_URL |
| PostgreSQL | DATABASE_URL |
| KibokanDB | KIBOKAN_HOST |
| SMTP Server | SMTP_SETTINGS |
It is written as a JSON.
SMTP_SETTINGS='{ "address": "localhost", "port": 25 }'
The properties of JSON are defined in ActionMailer (refer to Action Mailer Basics — Ruby on Rails Guides).