If using Ryanair check their Travel Documentation. They don't accept a driving licence. I've never used them to Dublin but often to Kerry and have to show my passport. There may be other documents they accept but nothing that I have other than my passport.
Hi DT. Ever tried to get a bottle of Irish Tomato sauce through Kerry airport on Ryanair? So excited they got with that in the daughter's bag they missed what was in mine and that could have been dangerous!