Choosing a user login/authentication system

hi,

i’m at the point in my app where i’m ready to release it into the wild
(in this
case my internal work intranet, not on the internet), and the only thing
holding it up is the implementation of a some sort of
login/authentication
system.

i know there are a bunch of login system generators and plugins that are
available, but I’m not sure which one to use. the setup of the
application is
extremely simple; basically a list of products with some detail
information
that i (the admin) updates, and the rest of the world only has read-only
access. no shopping carts, no designer/author/publisher paradigms-- you
either
can change the data or you can’t.

for such a simple case, should I even bother with a prefab solution, and
just
write one myself? or is that a recipe for disaster (keeping in mind a
looming
deadline and limited, but growing, ruby/rails skills)? if a home-grown
solution is not the answer, which of the available pre-made modules
would be
best for this situation?

thanks in advance for any insight.