banger

Minimal Firecracker launcher.

Requirements

./run.sh

./run.sh --name calm_otter --vcpu 4 --ram 2048 --disk-size 6G

--name: must be unique and match [a-z0-9][a-z0-9_-]{0,63}.
--vcpu: defaults to 2, max 16.
--ram: MiB, defaults to 1024, max 32768.
--disk-size: M/G suffixes supported; must be >= base rootfs.ext4 size. Requires resize2fs.
DNS_SERVERS: optional env var for resolv.conf (default: 1.1.1.1). Requires debugfs.

ssh -i "./id_ed25519" root@<guest_ip>

VMs do not get internet access by default. You must enable forwarding and NAT:

./nat.sh up <id-or-name-prefix>

This enables net.ipv4.ip_forward=1 and installs per-VM NAT rules for the VM's guest IP and TAP device. To remove rules:

./nat.sh down <id-or-name-prefix>

Check status with:

./nat.sh status <id-or-name-prefix>

reboot

Each VM writes a metadata file at state/vms/<id>/info with the following fields:

id: unique identifier for the VM instance.
pid: Firecracker process ID.
created_at: timestamp when the VM was launched.
guest_ip: IP address assigned to the guest.
tap: host TAP interface name attached to the bridge.
api_sock: path to the Firecracker API socket (stored under $XDG_RUNTIME_DIR/banger/ when available).
log: path to the Firecracker log file.
base_loop: loop device backing the base rootfs (if present).
cow_file: copy-on-write image file (if present).
cow_loop: loop device for the COW image (if present).
dm_name: device-mapper name for the merged rootfs (if present).
dm_dev: device-mapper device path for the merged rootfs (if present).

PCI: Fatal: No config space access function found and MissingAddressRange lines are expected with pci=off in run.sh.
SELinux: Could not open policy file ... is expected in the minimal rootfs.