What kind of sample is this?

Hello,

Let's say I want to conduct a study that requires older people. I know a few nursing homes and choose them accordingly. All residents are asked whether they want to participate.

Would that be a sample? I'm not sure if this isn't a full census, although a full census actually means that I'm surveying the entire target population, and that's not the case here. Or is it a sample because all residents are participating? I'm really unsure.
Additionally, if it is a sample, is it a convenience sample?

Maybe someone can help me.