One the lessons I learned during my years of Java development was that we had one single artifact for all environments. Later on I learned about the 12 factor app (https://12factor.net/) and how other languages/frameworks adopt that same approach which is great.

Especially around using environment variables: one artifact that gets its values from the environment being served on makes sense. For backend.

But for frontend development I quickly realized that doing this nowadays is simply overkill. With most of the projects I've worked on recently we are deploying to S3 with Cloudfront in front of it.

Which makes environment variable substitution part of the deployment life cycle: you generate your assets to the environment they are going to be deployed and that's cool. Any secrets in it (Sentry, Newrelic, Calibre, whatever) gets bundled in.

What are thoughts on that and how do you do your front end bundling?