Last Updated: 27 November 2013

architecture stack

Table of Contents

A stack is a complete deployment environment including the base operating system, the language runtime and associated libraries. As a result, different stacks support different runtime environments.

Stack summary

  Base Technology REE 1.8.7 MRI 1.8.7 MRI 1.9.2 MRI 1.9.3 MRI 2.0.0 Node.js Clojure Java Python Scala
Celadon Cedar Ubuntu 10.04  
Badious Bamboo Debian Lenny 5.0                

The only stack on which you can provision new apps is Cedar. The stack for existing apps can be determined using the stack CLI command.

$ heroku stack
* cedar

Here, the app is running on Celadon Cedar.

Migrating to Cedar

Migrating from previous stacks to Cedar allows an application to take advantage of a much more flexible and powerful runtime. Because the significant architectural differences, migrating to Cedar is a largely manual process.

You can find instructions for migrating to Cedar here.