Files
spinifex/build/microvm/init.sh
T
Josh Siviour 5cf5cba7ac fix(microvm): load virtio_net dependency chain explicitly in init (#311)
The LB system microVM stripped its module tree to virtio + fw_cfg +
failover, but init.sh only loaded qemu_fw_cfg and virtio_net. virtio_net
depends on net_failover -> failover; modprobe resolves that chain via
modules.dep, and load_mod()'s insmod-by-path fallback loads a single .ko
with no dependency resolution.

When the image is built on a kmod-less host (depmod skipped, no
modules.dep) the chain can't be resolved either way, so virtio_net fails
to load, no NIC appears ('no interface found for MAC'), the lb-agent has
no network, heartbeats never reach AWSGW and every LB hangs in
provisioning until the 5m e2e timeout. Baremetal runners ship kmod so
modules.dep is generated and the chain resolves — which is why the LB
suite passed there but failed on normal CI.

Load failover -> net_failover -> virtio_net explicitly bottom-up so the
NIC comes up regardless of whether modules.dep exists.
2026-06-08 08:44:57 +10:00

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#!/bin/sh
mount -t proc proc /proc
mount -t sysfs sys /sys
mount -t devtmpfs dev /dev
# virtio_mmio is built-in (CONFIG_VIRTIO_MMIO=y) so virtio-net devices are
# already enumerated by the time PID 1 runs — no modprobe needed.
# qemu_fw_cfg and virtio_net are =m in stock Alpine linux-virt, so load them.
#
# modprobe needs a usable modules.dep; when the image is built on a host whose
# depmod can't produce one, busybox modprobe silently no-ops and the module
# never loads — fw_cfg then never appears and init panics. insmod by explicit
# path needs no modules.dep, so fall back to it. Handles .ko and .ko.gz.
load_mod() {
modprobe "$1" 2>/dev/null && return 0
for ko in $(find /lib/modules -name "$1.ko" -o -name "$1.ko.gz" 2>/dev/null); do
insmod "$ko" 2>/dev/null && return 0
case "$ko" in
*.gz) gunzip -c "$ko" >/tmp/mod.ko 2>/dev/null \
&& insmod /tmp/mod.ko 2>/dev/null && return 0 ;;
esac
done
return 1
}
load_mod qemu_fw_cfg || load_mod fw_cfg_sysfs || true
# virtio_net depends on net_failover, which depends on failover. The load_mod
# insmod fallback loads a single .ko with no dependency resolution, and
# modules.dep is absent when the image is built on a kmod-less host (depmod
# skipped), so modprobe can't resolve the chain either. Load it explicitly
# bottom-up so the NIC comes up regardless of how the image was built —
# without this the agent has no network and the LB hangs in provisioning.
load_mod failover || true
load_mod net_failover || true
load_mod virtio_net || true
NETCFG=/sys/firmware/qemu_fw_cfg/by_name/opt/spinifex/netcfg/raw
i=0
while [ "$i" -lt 25 ]; do
[ -f "$NETCFG" ] && break
sleep 0.04
i=$((i + 1))
done
if [ ! -f "$NETCFG" ]; then
# Dump host/guest fw_cfg state to the serial console before init exits so a
# "netcfg not available" panic is diagnosable from the captured console log
# (module-not-loaded vs qemu-not-exposing-by_name vs wrong machine type).
echo "[init] FATAL: fw_cfg netcfg not available" >&2
echo "[init] dmi: vendor=$(cat /sys/class/dmi/id/sys_vendor 2>/dev/null) product=$(cat /sys/class/dmi/id/product_name 2>/dev/null) bios=$(cat /sys/class/dmi/id/bios_version 2>/dev/null)" >&2
echo "[init] qemu_fw_cfg dir present: $([ -d /sys/firmware/qemu_fw_cfg ] && echo yes || echo NO)" >&2
echo "[init] modules: $(lsmod 2>/dev/null | awk 'NR>1{print $1}' | tr '\n' ',')" >&2
echo "[init] by_name listing:" >&2
ls -la /sys/firmware/qemu_fw_cfg/by_name/ 2>&1 | sed 's/^/[init] /' >&2
ls -la /sys/firmware/qemu_fw_cfg/by_name/opt/ 2>&1 | sed 's/^/[init] /' >&2
echo "[init] dmesg fw_cfg:" >&2
dmesg 2>/dev/null | grep -i fw_cfg | sed 's/^/[init] /' >&2
exit 1
fi
. "$NETCFG"
for n in 0 1 2 3 4 5; do
eval mac=\$NIC${n}_MAC
[ -z "$mac" ] && continue
iface=""
for attempt in 1 2 3 4 5; do
iface=$(ip -o link | awk -v m="$mac" 'tolower($0) ~ tolower(m) {print $2}' | tr -d :)
[ -n "$iface" ] && break
sleep 0.02
done
if [ -z "$iface" ]; then
echo "[init] WARNING: no interface found for MAC $mac (NIC$n), skipping" >&2
continue
fi
eval cidr=\$NIC${n}_CIDR
eval gw=\$NIC${n}_GW
eval default=\$NIC${n}_DEFAULT
eval rdst=\$NIC${n}_ROUTE_DST
eval rvia=\$NIC${n}_ROUTE_VIA
ip link set "$iface" up
[ -n "$cidr" ] && ip addr add "$cidr" dev "$iface"
[ "$default" = "1" ] && [ -n "$gw" ] && ip route add default via "$gw" dev "$iface"
[ -n "$rdst" ] && [ -n "$rvia" ] && ip route add "$rdst" via "$rvia" dev "$iface"
done
cp /sys/firmware/qemu_fw_cfg/by_name/opt/spinifex/lb-agent-env/raw /etc/conf.d/lb-agent
mkdir -p /etc/ssl/certs
cp /sys/firmware/qemu_fw_cfg/by_name/opt/spinifex/ca-cert/raw /etc/ssl/certs/ca-certificates.crt
exec /sbin/init