open-standards/sandbox/sandbox-rs/crates/sandbox-exec-microvm/examples/boot_microvm.rs

//! Boot a real Firecracker microVM through the reference [`FirecrackerVmm`]
//! driver, meter the boot's CPU energy on real hardware (RAPL via MSR), and
//! seal the reading as a Sandbox JCR-1 receipt — the S5 executor's full path,
//! end to end, on a Linux KVM host.
//!
//! ```bash
//! # on a Linux KVM host (e.g. AWS *.metal), as root for MSR access:
//! sudo FC_BIN=/usr/local/bin/firecracker \
//!      KERNEL=/tmp/vmlinux.bin ROOTFS=/tmp/rootfs.ext4 \
//!      ./boot_microvm
//! ```
//!
//! It spawns `firecracker --api-sock <sock>`, drives `PUT /boot-source`,
//! `/drives/rootfs`, `/machine-config`, and the `InstanceStart` action through
//! our unix-socket HTTP/1.1 client, lets the guest run briefly, and reads the
//! package energy counter before and after. A genuine `HwShunt` figure where
//! the MSR is readable; an honest `ModelBased` vCPU-seconds estimate otherwise.

use sandbox_exec_microvm::firecracker::{FirecrackerConfig, FirecrackerVmm, VmState, Vmm};
use sandbox_exec_microvm::power::PowerMeter;
use sandbox_meter::{DeviceEnergy, Provenance, Receipt};
use sandbox_schema::{ContentId, DeviceClass, Tier};
use std::path::Path;
use std::process::Command;
use std::time::{Duration, Instant};

fn env(key: &str, default: &str) -> String {
    std::env::var(key).unwrap_or_else(|_| default.into())
}

fn main() {
    let fc_bin = env("FC_BIN", "/usr/local/bin/firecracker");
    let kernel = env("KERNEL", "/tmp/vmlinux.bin");
    let rootfs = env("ROOTFS", "/tmp/rootfs.ext4");
    let run_secs: f64 = env("RUN_SECS", "4").parse().unwrap_or(4.0);
    let sock = "/tmp/fc-demo.sock";
    let _ = std::fs::remove_file(sock);

    // Spawn the Firecracker process listening on the API socket.
    let mut child = Command::new(&fc_bin)
        .args(["--api-sock", sock])
        .spawn()
        .unwrap_or_else(|e| panic!("spawn {fc_bin}: {e}"));
    for _ in 0..100 {
        if Path::new(sock).exists() {
            break;
        }
        std::thread::sleep(Duration::from_millis(50));
    }

    // The meter: real RAPL via MSR where available (root on Nitro metal),
    // else None → an honest vCPU-seconds ModelBased estimate.
    #[cfg(target_os = "linux")]
    let meter: Option<sandbox_exec_microvm::power::MsrRaplMeter> =
        sandbox_exec_microvm::power::MsrRaplMeter::package0();
    #[cfg(not(target_os = "linux"))]
    let meter: Option<sandbox_exec_microvm::power::NoMeter> = None;

    let before = meter.as_ref().and_then(|m| m.sample_uj());
    println!(
        "meter: {}",
        if before.is_some() { "RAPL via MSR (HwShunt)" } else { "none — ModelBased fallback" }
    );

    let cfg = FirecrackerConfig {
        api_socket: sock.into(),
        kernel_image_path: kernel,
        rootfs_path: rootfs,
        boot_args: "console=ttyS0 reboot=k panic=1 pci=off root=/dev/vda rw".into(),
        vcpus: 2,
        mem_mib: 256,
    };

    let t0 = Instant::now();
    let outcome = FirecrackerVmm.run(&cfg);
    match &outcome {
        Ok(o) => println!("boot: {:?} ({} vcpu-s attributed)", o.state, o.vcpu_seconds),
        Err(e) => println!("boot error: {e}"),
    }
    // Let the guest run so the metered window covers real execution.
    std::thread::sleep(Duration::from_secs_f64(run_secs));
    let after = meter.as_ref().and_then(|m| m.sample_uj());
    let wall = t0.elapsed();
    let _ = child.kill();
    let _ = child.wait();
    let _ = std::fs::remove_file(sock);

    let booted = matches!(outcome.map(|o| o.state), Ok(VmState::Booted | VmState::Completed));
    println!("guest ran {:.2}s; booted={booted}", wall.as_secs_f64());

    // Build the energy record: HwShunt from the MSR delta, else ModelBased.
    let device = match (before, after) {
        (Some(a), Some(b)) => {
            let uj = b.saturating_sub(a);
            println!("CPU energy (RAPL pkg-0, MSR): {:.3} J over the window", uj as f64 / 1e6);
            DeviceEnergy {
                class: DeviceClass::Cpu,
                measured_uj: Some(uj),
                estimated_uj: uj,
                provenance: Provenance::HwShunt,
            }
        }
        _ => {
            // No hardware: vCPU-seconds × a coarse per-vCPU-second figure.
            let est = (cfg.vcpus as u64).saturating_mul(wall.as_secs().max(1)).saturating_mul(15_000_000);
            println!("CPU energy (estimate): {:.3} J", est as f64 / 1e6);
            DeviceEnergy {
                class: DeviceClass::Cpu,
                measured_uj: None,
                estimated_uj: est,
                provenance: Provenance::ModelBased,
            }
        }
    };

    // Seal it as a Sandbox S5 receipt.
    let receipt = Receipt::build(
        ContentId::of_bytes(b"firecracker microvm boot: vmlinux + bionic rootfs"),
        Tier::S5,
        vec![device],
        1,
        [9u8; 8],
    )
    .expect("receipt builds");
    let sk = ed25519_dalek::SigningKey::from_bytes(&[5u8; 32]);
    let envelope = receipt.seal("did:sandbox:metal-demo", &sk).expect("seal");
    receipt
        .verify_sealed(&envelope, &sk.verifying_key(), Some("did:sandbox:metal-demo"))
        .expect("verify");
    std::fs::write("/tmp/microvm-receipt.cose", &envelope).ok();
    println!(
        "sealed S5 receipt {} ({} bytes) — verified ✓; written to /tmp/microvm-receipt.cose",
        receipt.content_id().0,
        envelope.len()
    );
}