Crystal Heroku Buildpack

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

Usage

Create a Heroku app with this buildpack

heroku create --buildpack "https://github.com/msky026/heroku-buildpack-crystal.git"

Set the buildpack of an existing Heroku app

heroku config:set BUILDPACK_URL="https://github.com/msky026/heroku-buildpack-crystal.git"

Configuration

Create a crystal_buildpack.config file in your app's root dir. The file's syntax is bash.

For your reference crystal_buildpack.config.

Here's a full config file with all available options:

# Crystal version
crystal_version=0.24.0

# Always rebuild from scratch on every deploy?
always_rebuild=false

# Export heroku config vars
config_vars_to_export=(DATABASE_URL)

# A command to run right after compiling the app
post_compile="pwd"

# Build command
build_command=("shards update" "make db_migrate" "make build")

Specifying config vars to export at compile time

• To set a config var on your heroku node you can exec from the shell:

heroku config:set MY_VAR=the_value

• Add the config vars you want to be exported in your crystal_buildpack.config file:

config_vars_to_export=(DATABASE_URL MY_VAR)

Default config

If you don't specify a config option, then the default option file will be used.

# Use latest version
crystal_version=LATEST_VERSION
always_rebuild=false
config_vars_to_export=(DATABASE_URL)
build_command=("make run")

Other notes

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.

To learn more about using custom buildpacks in Heroku, read their docs.

Older versions of Crystal

If you have and older version of Crystal (<= 0.9), that uses the old Projectfile way of handling dependencies, you can use version 1.0 of the buildpack.