# banger

Minimal Firecracker launcher.

## Requirements
- Linux host with KVM (`/dev/kvm` access)
- `sudo`, `ip`, `curl`, `ssh`

## Files
- `firecracker`: Firecracker binary
- `vmlinux`: guest kernel
- `rootfs.ext4`: guest root filesystem
- `id_ed25519`: SSH key for `root`

## Run
```
./run.sh
```

## Run Options
```
./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`.

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

## Shutdown
```
reboot
```

## VM Info File
Each VM writes a metadata file at `state/vm-*/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.
- `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).

## Log Notes
- `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.