foreman only shows line with “started with pid #” and nothing else

I’ve been able to resolve this issue by 2 different ways:

1. From https://github.com/ddollar/foreman/wiki/Missing-Output:

   If you are not seeing any output from your program, there is a likely chance that it is buffering stdout. Ruby buffers stdout by default. To disable this behavior, add this code as early as possible in your program:

   # ruby
   $stdout.sync = true
   

2. By installing foreman via the heroku toolbelt package

But I still don’t know what’s happening nor why this 2 ways above resolved the issue…

My solution was to put $stdout.sync = true at the top of config/environments/development.rb.

Then everything that loads the development environment (incluing thin) will not buffer stdout.

"Foreman will display to the terminal output anything written to stdout by the processes it launches." - ddollar See foreman-issues#57

BTW, you can use tailf into Procfile to see logs

web: bundle exec rails server thin -p $PORT
log: tail -f log/development.log

Tip: tailf doesn't exist in OSX, using tail -f -n 40 log/development.log works.