When Drake turns 30, celebs come out of the woodwork to celebrate!

The rapper was feted by the likes of Taylor Swift, Katy Perry and John Mayer -- yes, ALL the exes were in the same room together! -- at an LA party Sunday night. Noticeably absent, however, was on-again-off-again girlfriend Rihanna!

About 150 of Drake's other friends were there, though, at h.wood group's Delilah, including Karlie Kloss and the Haim sisters. Sounds like TSwiz was Drizzy's party planner! Jamie Foxx, Zoe Kravitz and French Montana were also in attendance.

And the cutest thing EVER ... Drake's dad sang "Happy Birthday" to his son, with his mom standing by his side.