Struct ComputerConfig 

pub struct ComputerConfig {
    pub jailer: Option<JailerConfig>,
    pub data_dir: String,
    pub pool_size: usize,
    pub warm_create: bool,
    pub dmsetup_candidates: Option<Vec<String>>,
}

The [firecracker] keys this runtime reads.

The section is named for the VMM because that is what a deployed vmm.toml has always called it, and the on-disk vocabulary is frozen (computer/AGENTS.md) — but nothing here is Firecracker’s. The keys that configure a VMM adapter (its binaries, its process-level flags, the sandbox datapath) belong to whoever builds that adapter, and are read out of this same section by the composer; serde ignores what it does not know, so one section serves both halves and the file’s shape is unchanged.

Fields

jailer: Option<JailerConfig>

Jailer isolation for every sandbox VMM (absent = no isolation).

data_dir: String

Root data directory (VMs, snapshots, images).

pool_size: usize

Spare pre-warmed restore slots kept per snapshot id (CORE-78).

A slot pre-executes the fixed host-side restore setup — jailer chroot, Firecracker spawn, kernel/vmstate/mem staging, dm-snapshot — so a restore only claims it and issues LoadSnapshot. Only snapshots that have been restored at least once are pooled, for at most two distinct snapshot ids (LRU-evicted). 0 disables pooling.

warm_create: bool

Serve eligible Creates from warm template snapshots (CORE-77).

The first create of a template shape cold-boots and checkpoints the idle guest; every later create of the same shape restores from that snapshot instead of booting a kernel. Requires jailer isolation; only networked creates without a custom boot recipe participate. false restores plain cold boots for every create.

dmsetup_candidates: Option<Vec<String>>

Where to look for the dmsetup binary that drives dm-snapshot CoW rootfs images. The first entry that exists and answers dmsetup version wins; none usable disables CoW (every sandbox copies its rootfs). PATH is never searched. None — the field absent from the file — leaves the choice to the composer, whose fallback is the library’s stock-distro list; an explicit list is used exactly as written, so [] is how a config disables CoW.

Trait Implementations

impl Clone for ComputerConfig

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ComputerConfig

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for ComputerConfig

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for ComputerConfig

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.