How to send a multiline file to Heroku Config

On occasion, I’ll need to add sensitive configuration data to a Heroku application that happens to be multiline or contains non-alphanumeric characters. For example, uploading a public or private key file, where whitespace (including vertical whitespace) is significant. Another example that I ran into recently was uploading a JSON file for Google Auth configuration.

The solution is pretty straightforward:

$ heroku config:set FOO="$(< /my/file.json)"

That’s it. If you feel like it, you can confirm that the data is represented accurately by checking heroku config.

Perhaps this will help you if you’re in a similar situation. Cheers!