We're currently running a Ruby on Rails project (RefineryCMS) on Heroku with two dynos.
Every time we update the site we experience downtime for about 1 to 2 minutes. Management are not happy about this.
What we'd really like is some sort of (transparent) Blue-Green Deployment: http://martinfowler.com/bliki/BlueGreenDeployment.html
Is this possible to achieve on Heroku or another cloud platform as a service?
We're also using Unicorn, but happy to change if necessary.
Have a look at Heroku pre-boot it's a labs feature but sounds like exactly what you need.
Heroku don't support Blue/Green deployment.
I open an issue on that to Heroku support and they reply that Cedar stack wasn't designed for that. So you can't really prevent downtimes
The preboot feature will not help you if your application failed to start(due to config issue or large migration at part of the start-up phase).
来源：https://stackoverflow.com/questions/15500530/blue-green-deployment-on-heroku-or-another-cloud-platform-as-a-service