Deploy to Heroku button with env variables

Question

I'd like to add a "Deploy to Heroku" button to my application hosted on GitHub, but the only problem is it requires env variables to run, and will require the user to enter them before it will work. Is there a way in the app.json schema to prompt the user prior to install to set these up? Or is my best bet setting them to a standard string such as "replace_me" and telling the users to enter their data from there in my readme file.

I saw that you could generate a "secret" in their documentation but I'm not sure if that's what I'm looking for.

Answer 1

You may have found this already, but it looks like you define the env variables in the app.json schema. (Described more in detail here: https://blog.heroku.com/introducing_the_app_json_application_manifest)

The example schema they provide:

{
  "name": "Ruby on Rails",
  "description": "A template for getting started with the popular Ruby framework.",
  "website": "http://rubyonrails.org",
  "success_url": "/welcome",
  "addons": ["heroku-postgresql:hobby-dev", "papertrail"],
  "env": {
    "RAILS_ENV": "production",
    "COOKIE_SECRET": {
            "description": "This gets generated",
            "generator": "secret"
    },
    "SETUP_BY": {
            "description": "Who initiated this setup",
            "value": ""
    }
  },
  "scripts": {
    "postdeploy": "bundle exec rake db:migrate"
  }
}

Then, when you visit this deploy URL, you pass in the path to your Github repository where the app.json file lives, as well as any hard-coded ENV variables in the URL:

https://heroku.com/deploy?template=https://github.com/rauchg/slackin/tree/0.5.1& env[SLACK_SUBDOMAIN]=testdomain

When you visit the URL, it will automatically generate a form prompting you to enter the remaining env values.

Here's an example form generated by an app config I made here:

When the app deploys, it stores the values the user entered in the correct environment variables.