OpenURI is a really useful part of the Ruby standard library. I never used it with basic authentication but I thought than specify credential in URL was enough. I was wrong. It returns an error:
ArgumentError: userinfo not supported. [RFC3986]
The right way to use auth params is a bit hidden in the documentation page. You can find it in the OpenRead open method as option.
open("http://www.your-website.net", http_basic_authentication: ["user", "password"])