Heroku's Aspen stack is the product that launched our company and inspired a new class of cloud services. After much deliberation and careful thought, we have decided to sunset the Aspen stack by Thursday, November 22nd. We ask application owners still using Aspen to migrate to Cedar.
Since Aspen's launch over four years ago, Rails has seen the introduction of Bundler for dependency management, the asset pipeline, and a major framework re-write. Heroku has also grown, and with the introduction of the Cedar stack, we have moved beyond our humble origins and have become a true polyglot platform.
The Aspen stack was a prototype that served as a living vision of what a platform that focused on developer productivity and happiness could achieve. While there are many things developers loved about Aspen, the limitations have grown more apparent with time. On Aspen: Ruby is the only supported language, the version is locked, and there is no support for Rails beyond 3.0. As a result the number of apps left on Aspen is very small and decreasing steadily. Heroku has deployed over a million applications and taken all of the lessons learned running Aspen and Bamboo to build our most robust stack ever: Cedar.
Cedar gives users the flexibility to install extra dependencies, run custom buildpacks, and it has built-in support for many popular programming languages and frameworks in addition to Ruby and Rails.
Although we are sunsetting Aspen, applications running on Bamboo or Cedar will not be affected. Heroku is betting big on the Cedar stack - it's our most advanced and flexible stack, and we have no plans to replace Cedar.
Heroku is proud to be an erosion resistant platform and has run a large number of Aspen apps for years with no need for change or deployment. Although Heroku protects you from accidental change, when change needs to happen you deserve to know. Because of this we have outlined our deprecation and sunsetting policy to let you know what to expect. While the Aspen stack has proved to be stable, most developers have chosen to move their apps to Cedar.
This is the first time Heroku has sunset a stable stack from operation, and we are not taking this process lightly. By sunsetting Aspen we hope to be able to better serve all of our customers' needs and to continue to give migrated applications uninterrupted service.
Functionality on the Aspen stack will be gradually diminished as the stack is slowly phased out and we ask application owners to migrate to Cedar. As of now you will not be able to create new Aspen apps; in the future Git pushes will no longer be functional, and add-ons will not be able to be provisioned. On Thursday, November 22nd, all applications that have not requested an extension will no longer be functional. Owners of paid Aspen apps have been individually contacted about this change. We provided migration instructions, a contact for requesting an extension, and many of them have already migrated their apps. If you are an Aspen application owner and you have questions, please contact support.
Since Aspen debuted in 2009, both the Ruby/Rails community and Heroku have grown substantially. Back then, developers spent days or weeks setting up servers, configuring webservers, setting up databases. Heroku turned all that into a single
git push heroku master. While we're proud of the legacy Aspen represents, we acknowledge that it's time to retire Heroku's first grand experiment, and turn all our efforts toward the future.