Is there a way in Traefik v1 to serve a static robots.txt file on /robots.txt on all the sites proxied?
First, Traefik v1 is deprecated and unmaintained for several years.
Traefik is a reverse proxy and not a web server, which means it doesn't serve files or sites.
Traefik is managing routes.
So it's not possible to do what you are asking for.
Does Traefik v2 have this option? Or is it possible to upload a file from another container somehow?
Traefik is a reverse proxy and not a web server, which means it doesn't serve files or sites.
This doesn't depend on the version of Traefik.
You need to understand the difference like that you will be able to think about the problem differently.
You can create one or several routes to a container that serves a file but Traefik will never serve/upload files because Traefik is a reverse proxy.