I have Ruby on Rails 5, NginX, and Ubuntu 16.04. running on my droplet. The app has been running for a number of years, however, for some reason it keeps reverting back to development mode.

Every time I run rake about it tells me that Rails is in development mode.

This is strange because I am telling Rails very clearly that I want it to run in production mode, for example in my unicorn configuration file:

ENV="production"

Whenever I do something on the server, for example, run a migration I tell Rails that it should be done in a production context:

rake db:migrate RAILS_ENV=production

But still Rails seems to be running in development mode all the time.

This command doesn't help either:

RAILS_ENV=production rake about

How can I set my Rails app to production mode permanently?