Rails Env vs Jets Env

We’ll cover the difference between RAILS_ENV and JETS_ENV and how they should be used.

Short vs Long Names

Jets 6 and above uses shows short env names for JETS_ENV. Examples:


RAILS_ENV is a separate thing and uses long names. Examples:



When you deploy, JETS_ENV=dev is the default.

jets deploy # same as JETS_ENV=dev jets deploy

To deploy a production version of your site

JETS_ENV=prod jets deploy

Intesresting in both cases, RAILS_ENV=production. Your RAILS_ENV should always be RAILS_ENV=production and set in:



This is because RAILS_ENV=development will not work when on AWS Lambda. The reasons:

  • AWS Lambda has a read-only filesystem. Rails in development mode will do things like create folders and files and it won’t work on a read-only filesystem.
  • Rails development mode is really designed for you local machine and will do things like hot reloading etc. When running on AWS Lambda these things won’t work well.
  • When running on AWS Lambda, RAILS_ENV=production settings should always be used.
  • If you need to have different behaviors depending on development vs production, you can check Jets.env == "dev" or Jets.env == "prod" instead.