You can either provide a delegate to manually instantiate your cache provider or directly provide an instance:
services.AddSingleton<ICacheProvider>(provider => new RedisCacheProvider("myPrettyLocalhost:6379"));
services.AddSingleton<ICacheProvider>(new RedisCacheProvider("myPrettyLocalhost:6379"));
Please note that the container will not explicitly dispose of manually instantiated types, even if they implement IDisposable. See the ASP.NET Core doc about Disposal of Services for more info.