I found a solution, as recommended in Puma issues - to use RACK_ENV
instead of RAILS_ENV
:
» RACK_ENV=production foreman start
16:04:34 web.1 | started with pid 372
16:04:34 web.1 | Puma starting in single mode...
16:04:34 web.1 | * Version 2.8.2 (ruby 2.1.1-p76), codename: Sir Edmund Percival Hillary
16:04:34 web.1 | * Min threads: 0, max threads: 16
16:04:34 web.1 | * Environment: production
16:04:35 web.1 | * Listening on tcp://0.0.0.0:9292
16:04:35 web.1 | Use Ctrl-C to stop