Program Lifecycle

In Aya, an instance of the Bpf type manages the lifetime of all the eBPF objects created through it.

Consider the following example:

use aya::Bpf;
use aya::programs::{Xdp, XdpFlags};

fn main() {
    {
        // (1)
        let mut bpf = Bpf::load_file("bpf.o"))?;

        let program: &mut Xdp = bpf.program_mut("xdp").unwrap().try_into().unwrap();
        // (2)
        program.load()?;
        // (3)
        program.attach("eth0", XdpFlags::default()).unwrap();
    }
    // (4)

}

1. When you call load or load_file, all the maps referenced by the eBPF code are created and stored inside the returned Bpf instance.
2. Similarly when you load a program to the kernel, it's stored inside the Bpf instance.
3. When you attach a program, it stays attached until the parent Bpf instance gets dropped.
4. At this point the bpf variable has been droppped. Our program and maps are detached/unloaded.