by amberframework

GitHub Readme.md

⚠️ Latest Amber v0.7.2 is not compatible with Crystal v0.25.0

Please use a .crystal-version file with 0.24.2 instead

Amber Heroku Buildpack

Based on Crystal Heroku Buildpack

Amber logo

You can create an app in Heroku with Amber's buildpack by running the following command:

$ heroku create myapp --buildpack amberframework/amber

The default behaviour is to use the latest crystal release. If you need to use a specific version create a .crystal-version file in your application root directory with the version that should be used (e.g. 0.17.1).


In order for the buildpack to work properly you should have a shard.yml file, as it is how it will detect that your app is a Crystal app.

Your application has to listen on a port defined by Heroku.

Append the following code to your config/application.cr file:

Amber::Server.configure do |settings|
  settings.port = ENV["PORT"].to_i if ENV["PORT"]?

To be able to use production enviroment config Heroku needs .amber_secret_key or .encryption_key during compilation process, so in this case you should remove the encryption key from .gitignore file.

DISCLAIMER: Don't publish encryption key in open source projects if you have sensitive config


To test a change to this buildpack, write a unit test in tests/run that asserts your change and run make test to ensure the change works as intended and does not break backwards compatibility.

More info

This buildpack have been configured to work with Amber Framework projects.

To learn more about how to deploy other Crystal applications to Heroku, read this blog post.

Older versions of Crystal

Currently latest Amber v0.3.6 is compatible with Crystal v0.23.1

Other versions aren't guaranteed to be compatible.

Edge version of the buildpack

The amberframework/amber buildpack from the Heroku Registry contains the latest stable version of the buildpack. If you'd like to use the latest buildpack code from this Github repository, you can set your buildpack to the Github URL:

heroku buildpacks:set https://github.com/amberframework/heroku-buildpack-amber