how-to-heroku.md

Running on Heroku

You can run Dynamo on Heroku using the Elixir third-party buildpack. Follow the steps from the README to create a Dynamo project, then do the following:

Create a new app:

From the project directory, create a new Heroku app and specify the buildpack:

$ heroku create --buildpack "https://github.com/goshakkk/heroku-buildpack-elixir.git" [app_name]

If you already have a Heroku app created, you can just set the BUILDPACK_URL config var:

$ heroku config:add BUILDPACK_URL="https://github.com/goshakkk/heroku-buildpack-elixir.git" -a YOUR_APP

Specify Erlang/OTP and Elixir versions

Elixir requires Erlang/OTP version R15 or greater. Specify a preferred Erlang/OTP version for the buildpack by creating a .preferred_otp_version:

$ echo "OTP_R16B" > .preferred_otp_version

By default, the Elixir buildpack uses the master branch version of Elixir. You can specify a custom branch or tag name from the https://github.com/elixir-lang/elixir repository in the .preferred_elixir_version dotfile:

$ echo "master" > .preferred_elixir_version

Setup a Procfile

Heroku needs a Procfile in order to run your application. Create a Procfile with a web process defined:

$ echo 'web: MIX_ENV=prod mix server -p $PORT' > Procfile

Important Note: Single quotes are important here. $PORT is an environment variable supplied by Heroku. If you use double quotes in the above echo call, your local shell will try to interpolate the contents, and you'll end up with -p and not -p $PORT.

Deploy

Add and commit your changes, then push to Heroku:

$ git add Procfile .preferred_otp_version .preferred_elixir_version  
$ git commit -m "Setup for Heroku"  
$ git push heroku master

Don't forget to start a web process if you don't already have one:

$ heroku ps:scale web=1