David Kimura PRO said about 7 years ago on Decoding and Interacting with Barcodes :

Hello Dede,

I've pulled down the code from github and ran it in production mode.

The only difference that I made in the source app was add a secrets key in the secrets.yml file and run the app with RAILS_ENV=production passenger start as this will mount the rails app under nginx (similar to how it would be on a production environment).

I was able to get the camera showing without any issues.

You may want to check your browser to ensure that the camera was shared.