Firecracker-setup.md

Firecracker setup

Testing locally

Build vmlinux

cd kernel
./build.sh

Build rootfs

cd image-builder
go build .
sudo ./image-builder nodejs

By default there is no password set for root, to set it you need to mount the rootfs and change the password :

mkdir -p rootfs
sudo mount rootfs.ext4 rootfs
sudo chroot rootfs /bin/sh

# we're now in a shell in the image

passwd
# set your new password...

exit
sudo umount rootfs

Network setup on the host

sudo ip tuntap add tap0 mode tap
sudo ip link set tap0 up
sudo ip addr add 192.168.0.1/24 dev tap0

Change eth0 by the name of the interface on the host that is providing internet.

sudo iptables -t nat -A POSTROUTING -s 192.168.0.0/24 -o eth0 -j MASQUERADE
sudo iptables -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
sudo iptables -A FORWARD -s 192.168.0.0/24 -j ACCEPT

Start firecracker in a terminal

sudo rm -rf /tmp/firecracker.socket && sudo firecracker --api-sock /tmp/firecracker.socket

Start the VM

Set ROOTFS_PATH and KERNEL_PATH in setup-firecracker.sh to point to the generated files and then run the script :

sudo ./setup-firecracker.sh

Then setup the network on the guest

ip link set dev eth0 up
ip addr add 192.168.0.2/24 dev eth0
ip route add default via 192.168.0.1