I was told using GPL code is a problem (mongrel) even if not modifying that code

I was told that we can’t use mongrel with JRuby because mongrel is GPL and based on lawyer language if we include mongrel then our code violates some situation where someone could claim our code should become free. I always thought this would only apply if we modified the mongrel code base in any way then we have to make that mongrel version available but this is not what I am told but rather our code base (totally seperate from mongrel) can’t use mongrel …

This is somehow related to black duck, but I am still confused about what is going on here

You need to consult your lawyer but Mongrel offers a permissive license of their own under dual licensing: mongrel/LICENSE at master · mongrel/mongrel · GitHub you've the option to choose which you like, mongrel2 is BSD: https://github.com/zedshaw/mongrel2/blob/master/LICENSE

oops … I meant to say mongoDB

MongoDB's license doesn't affect your app because it goes through an API to access the data. Their drivers (AKA the Ruby driver) are Apache 2.0.