firecracker-hello-world.sh

set -eu

[ -e hello-vmlinux.bin ] || wget https://s3.amazonaws.com/spec.ccfc.min/img/hello/kernel/hello-vmlinux.bin
[ -e hello-rootfs.ext4 ] || wget -O hello-rootfs.ext4 https://raw.githubusercontent.com/firecracker-microvm/firecracker-demo/ec271b1e5ffc55bd0bf0632d5260e96ed54b5c0c/xenial.rootfs.ext4
[ -e hello-id_rsa ] || wget -O hello-id_rsa https://raw.githubusercontent.com/firecracker-microvm/firecracker-demo/ec271b1e5ffc55bd0bf0632d5260e96ed54b5c0c/xenial.rootfs.id_rsa

TAP_DEV="fc-88-tap0"


# set up the kernel boot args
MASK_LONG="255.255.255.252"
MASK_SHORT="/30"
FC_IP="169.254.0.21"
TAP_IP="169.254.0.22"
FC_MAC="02:FC:00:00:00:05"

KERNEL_BOOT_ARGS="ro console=ttyS0 noapic reboot=k panic=1 pci=off nomodules random.trust_cpu=on"
KERNEL_BOOT_ARGS="${KERNEL_BOOT_ARGS} ip=${FC_IP}::${TAP_IP}:${MASK_LONG}::eth0:off"

ip link del "$TAP_DEV" 2> /dev/null || true
ip tuntap add dev "$TAP_DEV" mode tap
sysctl -w net.ipv4.conf.${TAP_DEV}.proxy_arp=1 > /dev/null
sysctl -w net.ipv6.conf.${TAP_DEV}.disable_ipv6=1 > /dev/null
ip addr add "${TAP_IP}${MASK_SHORT}" dev "$TAP_DEV"
ip link set dev "$TAP_DEV" up

cat <<EOF > vmconfig.json
{
  "boot-source": {
    "kernel_image_path": "hello-vmlinux.bin",
    "boot_args": "$KERNEL_BOOT_ARGS"
  },
  "drives": [
    {
      "drive_id": "rootfs",
      "path_on_host": "hello-rootfs.ext4",
      "is_root_device": true,
      "is_read_only": false
    }
  ],
  "network-interfaces": [
      {
          "iface_id": "eth0",
          "guest_mac": "$FC_MAC",
          "host_dev_name": "$TAP_DEV"
      }
  ],
  "machine-config": {
    "vcpu_count": 2,
    "mem_size_mib": 1024,
    "ht_enabled": false
  }
}
EOF
firecracker --no-api --config-file vmconfig.json

@jvns FYI there is a 404 on: [ -e hello-rootfs.ext4 ] || wget -O hello-rootfs.ext4 https://raw.githubusercontent.com/firecracker-microvm/firecracker-demo/ec271b1e5ffc55bd0bf0632d5260e96ed54b5c0c/xenial.rootfs.ext4

This has moved to an S3 bucket, see upstream if you want to keep this up to date.

The JSON file now also appears to fail with firecracker 1.0 with:

2022-03-01T14:56:05.112106369 [anonymous-instance:main:ERROR:src/firecracker/src/main.rs:453] Configuration for VMM from one single json failed: Invalid JSON: unknown field `ht_enabled`, expected one of `vcpu_count`, `mem_size_mib`, `smt`, `cpu_template`, `track_dirty_pages` at line 24 column 16

Removing the ht_enabled field gets a bit further to:

[    0.091330] List of all partitions:
[    0.091665] No filesystem could mount root, tried: 
[    0.091666]  ext3
[    0.092067]  ext4
[    0.092217]  squashfs
[    0.092377] 
[    0.092733] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(254,0)
[    0.093341] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.14.55-84.37.amzn2.x86_64 #1
[    0.093893] Call Trace:
[    0.094086]  dump_stack+0x63/0x89
[    0.094335]  panic+0xdf/0x239
[    0.094557]  mount_block_root+0x27c/0x2af
[    0.094880]  ? set_debug_rodata+0x12/0x12
[    0.095181]  mount_root+0x65/0x68
[    0.095428]  prepare_namespace+0x12f/0x167
[    0.095783]  kernel_init_freeable+0x21a/0x247
[    0.096059]  ? rest_init+0xb0/0xb0
[    0.096059]  kernel_init+0x9/0x100
[    0.096059]  ret_from_fork+0x35/0x40
[    0.096059] Kernel Offset: disabled
[    0.096059] Rebooting in 1 seconds..

@alexellis The script will work if you use the images provided in firecracker repo readme.

Instead of

[ -e hello-vmlinux.bin ] || wget https://s3.amazonaws.com/spec.ccfc.min/img/hello/kernel/hello-vmlinux.bin
[ -e hello-rootfs.ext4 ] || wget -O hello-rootfs.ext4 https://raw.githubusercontent.com/firecracker-microvm/firecracker-demo/ec271b1e5ffc55bd0bf0632d5260e96ed54b5c0c/xenial.rootfs.ext4
[ -e hello-id_rsa ] || wget -O hello-id_rsa https://raw.githubusercontent.com/firecracker-microvm/firecracker-demo/ec271b1e5ffc55bd0bf0632d5260e96ed54b5c0c/xenial.rootfs.id_rsa

Use

arch=`uname -m`
dest_kernel="hello-vmlinux.bin"
dest_rootfs="hello-rootfs.ext4"
image_bucket_url="https://s3.amazonaws.com/spec.ccfc.min/img/quickstart_guide/$arch"

if [ ${arch} = "x86_64" ]; then
    kernel="${image_bucket_url}/kernels/vmlinux.bin"
    rootfs="${image_bucket_url}/rootfs/bionic.rootfs.ext4"
elif [ ${arch} = "aarch64" ]; then
    kernel="${image_bucket_url}/kernels/vmlinux.bin"
    rootfs="${image_bucket_url}/rootfs/bionic.rootfs.ext4"
else
    echo "Cannot run firecracker on $arch architecture!"
    exit 1
fi

if [ ! -f $dest_kernel ]; then
    echo "Kernel not found, downloading $kernel..."
    curl -fsSL -o $dest_kernel $kernel
    echo "Saved kernel file to $dest_kernel."
fi

if [ ! -f $dest_rootfs ]; then
    echo "Rootfs not found, downloading $rootfs..."
    curl -fsSL -o $dest_rootfs $rootfs
    echo "Saved root block device to $dest_rootfs."
fi

echo "Downloading public key file..."
[ -e hello-id_rsa ] || wget -O hello-id_rsa https://raw.githubusercontent.com/firecracker-microvm/firecracker-demo/ec271b1e5ffc55bd0bf0632d5260e96ed54b5c0c/xenial.rootfs.id_rsa
echo "Saved public key file."

For anyone running the initial script and failing with "unknown field ht_enabled", have in mind that ht_enabled has been renamed to smt. See also https://github.com/search?q=repo%3Afirecracker-microvm%2Ffirecracker%20ht_enabled&type=code

Can someone please provide me a script which "just works" as I am trying to tinker with firecracker but I just cannot seem to do so

Thanks and have a nice day to everyone involved, this script and the blog post seems fascinating to look at!