This is a simple sample application designed to showcase Heroku Release Phases, a feature which allows you to automate deploy tasks right before a Heroku app is made publicly available. In this example, a static asset is uploaded to an S3 instance and said asset is referenced in one of the views with help from a S3-hosted base URL for the asset injected in via an environment variable.

The repository includes a set of static assets — in this case, an image and a CSS file — which, at the time of deploy, are coped into S3 (or overwritten) and then referenced in the views.

The release phase task, defined in the Procfile is a standalone, lightweight node application which uploads the assets from the public folder into S3.

Any arbitray code or shell script could be executed in this phase.

You will need:

• A Heroku account
• An Amazon S3 account w/ appropriate public read settings

You'll need the following environment variables to make this work:

• AMAZON_S3_BASE_URL - The fully-qualified S3 base URL for public access to assets stored in S3
• AMAZON_S3_BUCKET_NAME - The bucket name for your specific S3 bucket where assets will be uploaded
• AMAZON_S3_KEY
• AMAZON_S3_SECRET

Big thanks to ![Steve S.] @ Heroku for the help. Heroku Solution Engineers are legit.