banger/scripts/customize.sh

#!/usr/bin/env bash
set -euo pipefail

log() {
  printf '[customize] %s\n' "$*"
}

usage() {
  cat <<'EOF'
Usage: ./scripts/customize.sh <base-rootfs> [--out <path>] [--size <size>] [--kernel <path>] [--initrd <path>] [--docker] [--modules <dir>]

Creates a copy of rootfs.ext4, optionally resizes it, boots a VM using the
copy as a writable rootfs, then applies base configuration and packages.
EOF
}

parse_size() {
  local raw="$1"
  if [[ "$raw" =~ ^([0-9]+)([KMG])?$ ]]; then
    local num="${BASH_REMATCH[1]}"
    local unit="${BASH_REMATCH[2]}"
    case "$unit" in
      K) echo $((num * 1024)) ;;
      M|"") echo $((num * 1024 * 1024)) ;;
      G) echo $((num * 1024 * 1024 * 1024)) ;;
    esac
    return 0
  fi
  return 1
}

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
REPO_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"
STATE="${BANGER_STATE_DIR:-${XDG_STATE_HOME:-$HOME/.local/state}/banger/image-build}"
VM_ROOT="$STATE/vms"
mkdir -p "$VM_ROOT"

BR_DEV="br-fc"
BR_IP="172.16.0.1"
CIDR="24"
DNS_SERVER="1.1.1.1"

resolve_banger_bin() {
  if [[ -n "${BANGER_BIN:-}" ]]; then
    printf '%s\n' "$BANGER_BIN"
    return
  fi
  if [[ -x "$REPO_ROOT/build/bin/banger" ]]; then
    printf '%s\n' "$REPO_ROOT/build/bin/banger"
    return
  fi
  if [[ -x "$REPO_ROOT/banger" ]]; then
    printf '%s\n' "$REPO_ROOT/banger"
    return
  fi
  if command -v banger >/dev/null 2>&1; then
    command -v banger
    return
  fi
  log "banger binary not found; install/build banger or set BANGER_BIN"
  exit 1
}

BANGER_BIN="$(resolve_banger_bin)"
NAT_ACTIVE=0
FC_BIN="$("$BANGER_BIN" internal firecracker-path)"
SSH_KEY="$("$BANGER_BIN" internal ssh-key-path)"
VSOCK_AGENT="$("$BANGER_BIN" internal vsock-agent-path)"

banger_nat() {
  local action="$1"
  "$BANGER_BIN" internal nat "$action" --guest-ip "$GUEST_IP" --tap "$TAP_DEV"
}

load_package_preset() {
  local preset="$1"
  local -n out="$2"
  mapfile -t out < <("$BANGER_BIN" internal packages "$preset")
  (( ${#out[@]} > 0 ))
}

write_rootfs_manifest_metadata() {
  local rootfs_path="$1"
  local manifest_hash="$2"
  printf '%s\n' "$manifest_hash" > "${rootfs_path}.packages.sha256"
}

BASE_ROOTFS=""
OUT_ROOTFS=""
SIZE_SPEC=""
INSTALL_DOCKER=0
KERNEL=""
INITRD=""
MISE_VERSION="v2025.12.0"
MISE_INSTALL_PATH="/usr/local/bin/mise"
MISE_ACTIVATE_LINE='eval "$(/usr/local/bin/mise activate bash)"'
TMUX_PLUGIN_DIR="/root/.tmux/plugins"
TMUX_RESURRECT_DIR="/root/.tmux/resurrect"
TMUX_TPM_REPO="https://github.com/tmux-plugins/tpm"
TMUX_RESURRECT_REPO="https://github.com/tmux-plugins/tmux-resurrect"
TMUX_CONTINUUM_REPO="https://github.com/tmux-plugins/tmux-continuum"
TMUX_MANAGED_START="# >>> banger tmux plugins >>>"
TMUX_MANAGED_END="# <<< banger tmux plugins <<<"
MODULES_DIR=""
while [[ $# -gt 0 ]]; do
  case "$1" in
    --out)
      OUT_ROOTFS="${2:-}"
      shift 2
      ;;
    --size)
      SIZE_SPEC="${2:-}"
      shift 2
      ;;
    --kernel)
      KERNEL="${2:-}"
      shift 2
      ;;
    --initrd)
      INITRD="${2:-}"
      shift 2
      ;;
    --docker)
      INSTALL_DOCKER=1
      shift
      ;;
    --modules)
      MODULES_DIR="${2:-}"
      shift 2
      ;;
    -h|--help)
      usage
      exit 0
      ;;
    *)
      if [[ -z "$BASE_ROOTFS" ]]; then
        BASE_ROOTFS="$1"
        shift
      else
        log "unknown option: $1"
        usage
        exit 1
      fi
      ;;
  esac
done

if [[ -z "$BASE_ROOTFS" ]]; then
  usage
  exit 1
fi

if [[ ! -f "$BASE_ROOTFS" ]]; then
  log "base rootfs not found: $BASE_ROOTFS"
  exit 1
fi

if [[ -z "$OUT_ROOTFS" ]]; then
  base_dir="$(dirname "$BASE_ROOTFS")"
  base_name="$(basename "$BASE_ROOTFS")"
  OUT_ROOTFS="${base_dir}/docker-${base_name}"
fi
if [[ "$OUT_ROOTFS" == *.ext4 ]]; then
  WORK_SEED="${OUT_ROOTFS%.ext4}.work-seed.ext4"
else
  WORK_SEED="${OUT_ROOTFS}.work-seed"
fi
if [[ -z "$KERNEL" ]]; then
  log "kernel path is required; pass --kernel"
  exit 1
fi
if [[ ! -f "$KERNEL" ]]; then
  log "kernel not found: $KERNEL"
  exit 1
fi
if [[ -n "$INITRD" && ! -f "$INITRD" ]]; then
  log "initrd not found: $INITRD"
  exit 1
fi
if [[ -n "$MODULES_DIR" && ! -d "$MODULES_DIR" ]]; then
  log "modules dir not found: $MODULES_DIR"
  exit 1
fi

if [[ -e "$OUT_ROOTFS" ]]; then
  log "output rootfs already exists: $OUT_ROOTFS"
  exit 1
fi

if ! command -v resize2fs >/dev/null 2>&1; then
  log "resize2fs required"
  exit 1
fi
if ! command -v jq >/dev/null 2>&1; then
  log "jq required"
  exit 1
fi
if ! command -v sha256sum >/dev/null 2>&1; then
  log "sha256sum required to record package preset metadata"
  exit 1
fi
if [[ ! -x "$VSOCK_AGENT" ]]; then
  log "vsock agent not found or not executable: $VSOCK_AGENT"
  log "run 'make build'"
  exit 1
fi

APT_PACKAGES=()
if ! load_package_preset debian APT_PACKAGES; then
  log "debian package preset is empty"
  exit 1
fi
if ! PACKAGES_HASH="$(printf '%s\n' "${APT_PACKAGES[@]}" | sha256sum | awk '{print $1}')"; then
  log "failed to hash package preset"
  exit 1
fi
printf -v APT_PACKAGES_ESCAPED '%q ' "${APT_PACKAGES[@]}"

log "copying base rootfs to $OUT_ROOTFS"
cp --reflink=auto "$BASE_ROOTFS" "$OUT_ROOTFS"

if [[ -n "$SIZE_SPEC" ]]; then
  SIZE_BYTES="$(parse_size "$SIZE_SPEC")"
  BASE_BYTES="$(stat -c%s "$BASE_ROOTFS")"
  if [[ -z "$SIZE_BYTES" || "$SIZE_BYTES" -lt "$BASE_BYTES" ]]; then
    log "size must be >= base image size"
    exit 1
  fi
  log "resizing rootfs to $SIZE_SPEC"
  truncate -s "$SIZE_BYTES" "$OUT_ROOTFS"
  e2fsck -p -f "$OUT_ROOTFS" >/dev/null
  resize2fs "$OUT_ROOTFS" >/dev/null
fi

VM_ID="$(head -c 32 /dev/urandom | xxd -p -c 256)"
VM_TAG="${VM_ID:0:8}"
VM_NAME="customize-${VM_TAG}"
VM_DIR="$VM_ROOT/$VM_ID"
mkdir -p "$VM_DIR"

API_SOCK="${XDG_RUNTIME_DIR:-/run/user/$(id -u)}/banger/fc-$VM_TAG.sock"
LOG_FILE="$VM_DIR/firecracker.log"
TAP_DEV="tap-fc-$VM_TAG"

# Allocate guest IP
NEXT_IP_FILE="$STATE/next_ip"
NEXT_IP="$(cat "$NEXT_IP_FILE" 2>/dev/null || echo 2)"
GUEST_IP="172.16.0.$NEXT_IP"
echo "$((NEXT_IP + 1))" > "$NEXT_IP_FILE"

sudo -v

cleanup() {
  sudo kill "${FC_PID:-}" 2>/dev/null || true
  if [[ "$NAT_ACTIVE" -eq 1 ]]; then
    banger_nat down >/dev/null 2>&1 || true
  fi
  sudo ip link del "$TAP_DEV" 2>/dev/null || true
  rm -f "$API_SOCK"
  rm -rf "$VM_DIR"
}
trap cleanup EXIT

sudo mkdir -p "$(dirname "$API_SOCK")"
sudo chown "$(id -u):$(id -g)" "$(dirname "$API_SOCK")"

# Host bridge
if ! ip link show "$BR_DEV" >/dev/null 2>&1; then
  log "creating host bridge $BR_DEV ($BR_IP/$CIDR)"
  sudo ip link add name "$BR_DEV" type bridge
  sudo ip addr add "${BR_IP}/${CIDR}" dev "$BR_DEV"
  sudo ip link set "$BR_DEV" up
else
  sudo ip link set "$BR_DEV" up
fi

log "creating tap device $TAP_DEV"
TAP_USER="${SUDO_UID:-$(id -u)}"
TAP_GROUP="${SUDO_GID:-$(id -g)}"
sudo ip tuntap add dev "$TAP_DEV" mode tap user "$TAP_USER" group "$TAP_GROUP"
sudo ip link set "$TAP_DEV" master "$BR_DEV"
sudo ip link set "$TAP_DEV" up
sudo ip link set "$BR_DEV" up

log "starting firecracker process"
rm -f "$API_SOCK"
nohup sudo -E "$FC_BIN" --api-sock "$API_SOCK" >"$LOG_FILE" 2>&1 &
FC_PID="$!"

log "waiting for firecracker api socket"
for _ in $(seq 1 200); do
  [[ -S "$API_SOCK" ]] && break
  sleep 0.02
done
[[ -S "$API_SOCK" ]] || { log "firecracker api socket not ready"; exit 1; }

log "configuring machine"
sudo -E curl --unix-socket "$API_SOCK" -X PUT http://localhost/machine-config \
  -H "Content-Type: application/json" \
  -d '{
    "vcpu_count": 2,
    "mem_size_mib": 1024,
    "smt": false
  }' >/dev/null

KCMD="console=ttyS0 reboot=k panic=1 pci=off root=/dev/vda rw ip=${GUEST_IP}::${BR_IP}:255.255.255.0:${VM_NAME}:eth0:off:${DNS_SERVER} hostname=${VM_NAME} systemd.mask=home.mount systemd.mask=var.mount"

INITRD_JSON=""
if [[ -n "$INITRD" ]]; then
  INITRD_JSON=", \"initrd_path\": \"$INITRD\""
fi

sudo -E curl --unix-socket "$API_SOCK" -X PUT http://localhost/boot-source \
  -H "Content-Type: application/json" \
  -d "{
    \"kernel_image_path\": \"$KERNEL\",
    \"boot_args\": \"$KCMD\"${INITRD_JSON}
  }" >/dev/null

sudo -E curl --unix-socket "$API_SOCK" -X PUT http://localhost/drives/rootfs \
  -H "Content-Type: application/json" \
  -d "{
    \"drive_id\": \"rootfs\",
    \"path_on_host\": \"$OUT_ROOTFS\",
    \"is_root_device\": true,
    \"is_read_only\": false
  }" >/dev/null

sudo -E curl --unix-socket "$API_SOCK" -X PUT http://localhost/network-interfaces/eth0 \
  -H "Content-Type: application/json" \
  -d "{
    \"iface_id\": \"eth0\",
    \"host_dev_name\": \"$TAP_DEV\"
  }" >/dev/null

sudo -E curl --unix-socket "$API_SOCK" -X PUT http://localhost/actions \
  -H "Content-Type: application/json" \
  -d '{ "action_type": "InstanceStart" }' >/dev/null

SUDO_CHILD_PID="$(pgrep -n -f "$API_SOCK" || true)"
if [[ -n "$SUDO_CHILD_PID" ]]; then
  FC_PID="$SUDO_CHILD_PID"
fi

VM_CONFIG_JSON="$(sudo -E curl --unix-socket "$API_SOCK" -sS http://localhost/vm/config)"
CREATED_AT="$(date -Iseconds)"
jq -n \
  --arg id "$VM_ID" \
  --arg name "$VM_NAME" \
  --arg pid "$FC_PID" \
  --arg created_at "$CREATED_AT" \
  --arg guest_ip "$GUEST_IP" \
  --arg tap "$TAP_DEV" \
  --arg api_sock "$API_SOCK" \
  --arg log "$LOG_FILE" \
  --arg rootfs "$OUT_ROOTFS" \
  --arg kernel "$KERNEL" \
  --argjson config "$VM_CONFIG_JSON" \
  '{meta:{id:$id,name:$name,pid:$pid,created_at:$created_at,guest_ip:$guest_ip,tap:$tap,api_sock:$api_sock,log:$log,rootfs:$rootfs,kernel:$kernel},config:$config}' \
  > "$VM_DIR/vm.json"

log "enabling NAT for customization"
banger_nat up >/dev/null
NAT_ACTIVE=1

log "waiting for SSH"
SSH_READY=0
for _ in $(seq 1 60); do
  if ssh -i "$SSH_KEY" -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null \
    "root@${GUEST_IP}" "true" >/dev/null 2>&1; then
    SSH_READY=1
    break
  fi
  sleep 1
done
if [[ "$SSH_READY" -ne 1 ]]; then
  log "ssh did not become ready on $GUEST_IP"
  exit 1
fi

log "configuring guest"
log "installing vsock agent"
scp -i "$SSH_KEY" -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null \
  "$VSOCK_AGENT" "root@${GUEST_IP}:/usr/local/bin/banger-vsock-agent" >/dev/null

ssh -i "$SSH_KEY" -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null \
  "root@${GUEST_IP}" bash -lc "set -e
printf 'nameserver %s\n' \"$DNS_SERVER\" > /etc/resolv.conf
echo \"$VM_NAME\" > /etc/hostname
printf '127.0.0.1 localhost\n127.0.1.1 %s\n' \"$VM_NAME\" > /etc/hosts
touch /etc/fstab
sed -i '\|^/dev/vdb[[:space:]]\+/home[[:space:]]|d; \|^/dev/vdc[[:space:]]\+/var[[:space:]]|d' /etc/fstab
if ! grep -q '^tmpfs /run ' /etc/fstab; then
  echo 'tmpfs /run tmpfs defaults,nodev,nosuid,mode=0755 0 0' >> /etc/fstab
fi
if ! grep -q '^tmpfs /tmp ' /etc/fstab; then
  echo 'tmpfs /tmp tmpfs defaults,nodev,nosuid,mode=1777 0 0' >> /etc/fstab
fi
apt-get update
DEBIAN_FRONTEND=noninteractive apt-get -y upgrade
DEBIAN_FRONTEND=noninteractive apt-get -y install ${APT_PACKAGES_ESCAPED}
curl -fsSL https://mise.run | MISE_INSTALL_PATH=\"$MISE_INSTALL_PATH\" MISE_VERSION=\"$MISE_VERSION\" sh
\"$MISE_INSTALL_PATH\" use -g github:anomalyco/opencode
\"$MISE_INSTALL_PATH\" reshim
if [[ ! -e /root/.local/share/mise/shims/opencode ]]; then
  echo 'opencode shim not found after mise install' >&2
  exit 1
fi
ln -snf /root/.local/share/mise/shims/opencode /usr/local/bin/opencode
mkdir -p /etc/profile.d
cat > /etc/profile.d/mise.sh <<'MISEPROFILE'
if [ -n \"\${BASH_VERSION:-}\" ] && [ -x \"$MISE_INSTALL_PATH\" ]; then
  eval \"\$($MISE_INSTALL_PATH activate bash)\"
fi
MISEPROFILE
chmod 0644 /etc/profile.d/mise.sh
touch /etc/bash.bashrc
if ! grep -Fqx '$MISE_ACTIVATE_LINE' /etc/bash.bashrc; then
  printf '\n%s\n' '$MISE_ACTIVATE_LINE' >> /etc/bash.bashrc
fi
if [[ \"$INSTALL_DOCKER\" == \"1\" ]]; then
  DEBIAN_FRONTEND=noninteractive apt-get -y remove containerd || true
  if ! DEBIAN_FRONTEND=noninteractive apt-get -y install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin; then
    DEBIAN_FRONTEND=noninteractive apt-get -y install docker.io
  fi
  if command -v systemctl >/dev/null 2>&1; then
    systemctl enable --now docker || true
  fi
fi
rm -f /root/get-docker /root/get-docker.sh /tmp/get-docker /tmp/get-docker.sh
chmod 0755 /usr/local/bin/banger-vsock-agent
mkdir -p /etc/modules-load.d /etc/systemd/system
cat > /etc/systemd/system/banger-opencode.service <<'EOF'
[Unit]
Description=Banger opencode server
After=network.target
RequiresMountsFor=/root

[Service]
Type=simple
Environment=HOME=/root
WorkingDirectory=/root
ExecStart=/usr/local/bin/opencode serve --hostname 0.0.0.0 --port 4096
Restart=on-failure
RestartSec=1

[Install]
WantedBy=multi-user.target
EOF
chmod 0644 /etc/systemd/system/banger-opencode.service
if command -v systemctl >/dev/null 2>&1; then
  systemctl daemon-reload || true
  systemctl enable --now banger-opencode.service || true
fi
cat > /etc/modules-load.d/banger-vsock.conf <<'EOF'
vsock
vmw_vsock_virtio_transport
EOF
chmod 0644 /etc/modules-load.d/banger-vsock.conf
cat > /etc/systemd/system/banger-vsock-agent.service <<'EOF'
[Unit]
Description=Banger vsock agent
After=network.target

[Service]
Type=simple
ExecStart=/usr/local/bin/banger-vsock-agent
Restart=on-failure
RestartSec=1

[Install]
WantedBy=multi-user.target
EOF
chmod 0644 /etc/systemd/system/banger-vsock-agent.service
if command -v systemctl >/dev/null 2>&1; then
  systemctl daemon-reload || true
  systemctl enable --now banger-vsock-agent.service || true
fi
git config --system init.defaultBranch main
"

log "configuring tmux resurrect"
ssh -i "$SSH_KEY" -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null \
  "root@${GUEST_IP}" bash -se <<EOF
set -euo pipefail

install_tmux_plugin() {
  local dir="\$1"
  local repo="\$2"

  if [[ -d "\$dir/.git" ]]; then
    git -C "\$dir" fetch --depth 1 origin
    git -C "\$dir" reset --hard FETCH_HEAD
  else
    rm -rf "\$dir"
    git clone --depth 1 "\$repo" "\$dir"
  fi
}

mkdir -p "$TMUX_PLUGIN_DIR" "$TMUX_RESURRECT_DIR"
install_tmux_plugin "$TMUX_PLUGIN_DIR/tpm" "$TMUX_TPM_REPO"
install_tmux_plugin "$TMUX_PLUGIN_DIR/tmux-resurrect" "$TMUX_RESURRECT_REPO"
install_tmux_plugin "$TMUX_PLUGIN_DIR/tmux-continuum" "$TMUX_CONTINUUM_REPO"

TMUX_CONF="/root/.tmux.conf"
tmp_tmux_conf="\$(mktemp)"
if [[ -f "\$TMUX_CONF" ]]; then
  awk -v begin="$TMUX_MANAGED_START" -v end="$TMUX_MANAGED_END" '
    \$0 == begin { skip = 1; next }
    \$0 == end { skip = 0; next }
    !skip { print }
  ' "\$TMUX_CONF" > "\$tmp_tmux_conf"
else
  : > "\$tmp_tmux_conf"
fi
if [[ -s "\$tmp_tmux_conf" ]]; then
  printf '\n' >> "\$tmp_tmux_conf"
fi
cat >> "\$tmp_tmux_conf" <<'TMUXCONF'
$TMUX_MANAGED_START
set -g @plugin 'tmux-plugins/tpm'
set -g @plugin 'tmux-plugins/tmux-resurrect'
set -g @plugin 'tmux-plugins/tmux-continuum'
set -g @continuum-save-interval '15'
set -g @continuum-restore 'off'
set -g @resurrect-dir '/root/.tmux/resurrect'
run '~/.tmux/plugins/tpm/tpm'
$TMUX_MANAGED_END
TMUXCONF
mv "\$tmp_tmux_conf" "\$TMUX_CONF"
chmod 0644 "\$TMUX_CONF"
EOF

if [[ -n "$MODULES_DIR" ]]; then
  MODULES_BASE="$(basename "$MODULES_DIR")"
  log "copying kernel modules ($MODULES_BASE) into guest"
  tar -C "$(dirname "$MODULES_DIR")" -cf - "$MODULES_BASE" | \
    ssh -i "$SSH_KEY" -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null \
      "root@${GUEST_IP}" bash -lc "set -e
mkdir -p /lib/modules
tar -C /lib/modules -xf -
depmod -a \"$MODULES_BASE\"
 mkdir -p /etc/modules-load.d
 printf 'nf_tables\nnft_chain_nat\nveth\nbr_netfilter\noverlay\n' > /etc/modules-load.d/docker-netfilter.conf
 mkdir -p /etc/sysctl.d
 cat > /etc/sysctl.d/99-docker.conf <<'SYSCTL'
net.bridge.bridge-nf-call-iptables = 1
net.bridge.bridge-nf-call-ip6tables = 1
net.ipv4.ip_forward = 1
SYSCTL
 sysctl --system >/dev/null 2>&1 || true
sync
"
fi

log "shutting down guest"
ssh -i "$SSH_KEY" -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null \
  "root@${GUEST_IP}" bash -lc "sync" || true
sudo -E curl --unix-socket "$API_SOCK" -X PUT http://localhost/actions \
  -H "Content-Type: application/json" \
  -d '{ "action_type": "SendCtrlAltDel" }' >/dev/null || true
for _ in $(seq 1 200); do
  if ! ps -p "$FC_PID" >/dev/null 2>&1; then
    break
  fi
  sleep 0.05
done
write_rootfs_manifest_metadata "$OUT_ROOTFS" "$PACKAGES_HASH"
log "building work seed $WORK_SEED"
"$BANGER_BIN" internal work-seed --rootfs "$OUT_ROOTFS" --out "$WORK_SEED"
log "done"