MIT online trainig has this great YouTube playlist on distributed systems, with one of the lectures being on RAFT [1,2,3]. The entire playlist [4] is probably worth your time, though.

[1] Intro https://www.youtube.com/watch?v=UzzcUS2OHqo

[2] Part I: https://www.youtube.com/watch?v=64Zp3tzNbpE

[3] Part II https://www.youtube.com/watch?v=4r8Mz3MMivY

[4] Playlist for the course: https://www.youtube.com/watch?v=cQP8WApzIQQ&list=PLrw6a1wE39...