There are many ways to greet a friend in the morning in Engpsh. Here are a few options:

Good morning!
Hey, how are you this morning?
Hello, how did you sleep?
Morning! Did you have a good night's rest?
Hi there! I hope your day is off to a great start.

You can choose which greeting to use based on the level of formapty and the relationship you have with the person you are greeting. It's also common to add a personal touch by asking how the person slept or expressing hope for their day.