Deploying Your Rails/JS App to Heroku - The Problems I Ran Into and How I Solved Them

When deploying my first Rails/JS (with Devise and Google’s OAuth2) app to Heroku I ran into a few speedbumps. Now, admittedly a few of these are rookie mistakes and I might have not run into them had I know more at the time but maybe my mistakes can still help out somone else in the future.

First Rookie Mistake: Make Sure You Precompile Your ES6 Code

If you don’t do this you might run into an error that looks something like this: Precompiling assets failed

  • To figure out what exactly was wrong I ran NODE_ENV=production RAILS_ENV=production rails assets:precompile --trace in my local console, which gave me the necessary hints to solve the problem.
  • Since I had very little ES6 code in my app at the time I decided to turn all ES6 to ES5 (it really wasn’t that much)
  • Better solution: Precompile your ES6!

Devise Secret Not Set

By running the same command, NODE_ENV=production RAILS_ENV=production rails assets:precompile --trace I recieved another error message:

Devise.secret_key was not set. Please add the following to your Devise initializer: config.secret_key = '3f64971...'

Simply do what it says and add that line to your config/initializers/devise.rb.

Run Your Migrations in Heroku

The home page worked at this point in time, but when I clicked on any link I would get my next error (definitely not the most helpful error message in the world): We're sorry, but something went wrong.

  • Turns out I hadn’t run rake db:migrate (and rake db:seed) in my heroku console yet. Doing that solved the problem. This StackOverflow question helped me get there.

Add Your Heroku URL in Your Google Developer Console (When Using Google’s OAuth2)

When trying to login through my Devise gem and through Google’s OAuth2 I received a redirect_uri_mismatch google oauth heroku error. The reason for this error is because I had only registered my localhost domain in my API console for this app. Again, StackOverflow saved the day.

To fix this:

  1. Go to your Google Developer Console
  2. Select your app at the top in the dropdown, if not already selected
  3. Go to credentials
  4. Go to your exisiting client (don’t create a new one)
  5. At the bottom under Authorized redirect URIs add your heroku app URL, like so: (your app might not be under users - compare it to your localhost url!)
  6. Save and you’re done.

I hope this will help someone sometime.