docker image fails when -it not specified

[elaygl]

I'm trying to use kubeval docker image with Teamcity.
When -it is not specified I'm getting the following error:
The document stdin appears to be empty

The command I used:
docker run --rm -v $(pwd)/namespaces:/namespaces garethr/kubeval:offline namespaces/*

[garethr]

I think this is the same issue described in #36, which has a few workarounds. I'm looking at making this simpler/documenting the behaviour. I'll close this particular issue but thanks for reporting.