How to identify a heroku dyno number from within the app?

Question

Is there a way to identify the heroku dyno name (e.g. web.1, web.2) from within the application? I'd like to be able to generate a unique request id (e.g. to track requests between web and worker dynos for consolidated logging of the entire request stack) and it seems to me that the dyno identifier would make a decent starting point.

If this can't be done, does anyone have a fallback recommendation?

Answer 1

Recently that issue has been addressed by Heroku team.

The Dyno Manager adds DYNO environment variables that holds identifier of your dyno e.g. web.1, web.2, foo.1 etc. However, the variable is still experimental and subject to change or removal.

I needed that value (actually instance index like 1, 2 etc) to initialize flake id generator at instance startup and this variable was working perfectly fine for me.

You can read more about the variables on Local environment variables.

Answer 2

The foreman package which heroku local uses seems to have changed the ENV variable name again (heroku/7.54.0). You can now get the worker name via $FOREMAN_WORKER_NAME when running locally. It has the same value $DYNO will have when running on Heroku (web.1, web.2, etc)