I wonder if the location of Rivendell is a secret known only by the wise such as Gandalf, or is it public to almost everyone in Middle-earth? 

As seen in the movie, Gandalf leads Bilbo Baggins and the dwarves through a narrow tunnel to escape from orcs, and none of them recognized that they were on the way to Rivendell. Also we see that Rivendell is not flooded with immigrants and poor people seeking refuge (compared to the Medieval Europe in our world, the life in Rivendell should be rather attractive for most people, except the richest ones), but only a few Elves live a secluded life. Does this suggest that the location of Rivendell is a secret?