Last updated 21 July 2015
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.
When you deploy an app, that app may contain its own runtime environment - so the list below is what’s available on the base stack only, not an indicator of what runtimes are ultimately available to your application.
|Celadon Cedar-14||Ubuntu 14.04||•||•||•||•||•||•||•|
|Celadon Cedar (deprecated)||Ubuntu 10.04||•||•||•||•||•||•||•|
$ heroku stack cedar-10 * cedar-14
Here, the app is running on Celadon Cedar-14.
You can change the stack for an existing application with the
stack:set command. For example:
$ heroku stack:set cedar-14 Stack set, next release on example-app will use cedar-14. Run `git push heroku master` to create a new release on cedar-14.
Migrating to a new stack
You will likely need to make changes to your application code as you move an app to a different stack. The
stack:set command will tell Heroku what stack to use, but it is your responsibility, as the application developer, to make any required changes to your code.
When migrating a production app to a new stack, you should perform the migration work on a staging version of the app in a separate code branch. Once you have tested that the app runs correctly on the new stack, you can merge in your changes on the production environment, change the stack with
stack:set and deploy.
Read migrating from Cedar to Cedar-14 to learn more.