"puts" output not displaying in Heroku logs for Sinatra app

Question

I'm trying to use "puts" to test a few things with a Sinatra app that's hosted on Heroku. Interestingly, the output seems to queue up and only displays upon restarting the Heroku dyno. I've tried with 'Thin' and 'Webrick', but have the same issue.

Any thoughts?

Using Heroku logs, yes. That's how I can see the output upon restarting the dyno. — dougiebuckets, Mar 07 '14 at 22:10
You might just need to sync stdout. Try adding `$stdout.sync = true` early in your apps startup (top of `config.ru` is a good place). — matt, Mar 07 '14 at 22:55

score 38 · Answer 1 · edited Sep 16 '14 at 11:04

38

As you can see on heroku docs: add this to your config.ru:

$stdout.sync = true

Don't forget the $ before stdout or it won't work.

edited Sep 16 '14 at 11:04

Josh

8,329
4
36
33

answered Aug 20 '14 at 07:14

Thiago Diniz

3,041
5
30
35

Thank you! I missed this in the docs and couldn't work out why I wasn't seeing my logs. – James Jan 03 '17 at 18:43

"puts" output not displaying in Heroku logs for Sinatra app

1 Answers1