Traefik is really cool for most usage, I tried to used it in production and here are some of the shortcoming I found (the 2 first issues are on github):

- If you use DNS for a blue-green deployment, traefik does not honor DNS ttls (because it uses the DNS of go and go might do some caching) so when you do the switch you might still end on the "old" environment

- An error on one of the cool feature: serving error page when your backend returns some HTTP code

- Some configuration options are not documented (but easily found using github search)

I still love this software and I will keep looking at it.