Continuous Delivery per Pull Request on Heroku

[discorick]

https://devcenter.heroku.com/articles/github-integration-review-apps

[dahlbyk]

So I got Heroku review apps set up on #201....and GitHub OAuth rejects auth because the URL doesn't match. This is...unfortunate.

[dahlbyk]

I mentioned this challenge to @Steven-Pingel and he directed me toward http://stackoverflow.com/a/32544022/54249. We should be able to use HEROKU_APP_NAME and HEROKU_PARENT_APP_NAME to effectively direct per-PR authorizations through the parent app.

[dahlbyk]

Looks like we're going to have to replace Warden::GitHub::Config.normalized_uri(), which is hard-coded to build redirect_uri from request.url.

[dahlbyk]

Now that the relevant code has been shipped, review apps can be deployed from https://dashboard.heroku.com/apps/huboard-rails/deploy/github. PRs without the new app.json (and relevant Warden code) won't work, so we'll want to pull master into any open branches that we want to review.