Dgraph on Cygwin/Windows not working

the problem i am facing without mounting the volume is that i am unable to load rdf files using the dgraphloader command.

PS C:\Users\esgazai\dgraph> docker exec -it dgraph dgraphloader -r 1million.rdf.gz

Dgraph version : v0.8.1
Commit SHA-1 : d86498f7
Commit timestamp : 2017-08-16 12:53:17 +1000
Branch : HEAD

Processing 1million.rdf.gz
2017/08/18 05:18:57 open 1million.rdf.gz: no such file or directory