Sample files to enable wireless on Debian initramfs

a_enable_wireless.sh

#!/bin/sh
# this goes into /etc/initramfs-tools/scripts/init-premount/a_enable_wireless
PREREQ=""
prereqs()
{
    echo "$PREREQ"
}

case $1 in
prereqs)
    prereqs
    exit 0
    ;;
esac

. /scripts/functions

AUTH_LIMIT=15
INTERFACE="wlp3s0"
alias WPACLI="/sbin/wpa_cli -p/tmp/wpa_supplicant -i$INTERFACE "

log_begin_msg "Starting haveged rng"
/usr/sbin/haveged -r 0 -p /run/initram-haveged.pid
log_begin_msg "Setting WLAN regdomain"
# Set this to your region
/sbin/iw reg set US
log_begin_msg "Starting WLAN connection"
/sbin/wpa_supplicant -Dnl80211,wext -i$INTERFACE -c/etc/wpa_supplicant.conf -P/run/initram-wpa_supplicant.pid -B -f/tmp/wpa_supplicant.log

# Wait for AUTH_LIMIT seconds, then check the status
limit=${AUTH_LIMIT}

echo -n "Waiting for connection (max ${AUTH_LIMIT} seconds)"
while [ $limit -ge 0 -a `WPACLI status | grep wpa_state` != "wpa_state=COMPLETED" ]
do
    sleep 1
    echo -n "."
    limit=`expr $limit - 1`
done
echo ""

if [ `WPACLI status | grep wpa_state` != "wpa_state=COMPLETED" ]; then
  ONLINE=0
  log_failure_msg "WLAN offline after timeout"
  #panic
  /sbin/iwconfig $INTERFACE power off
else
  ONLINE=1
  log_success_msg "WLAN online"
  /sbin/iwconfig $INTERFACE power off
  configure_networking
fi

enable-wireless.sh

# !/bin/sh
# This goes into /etc/initramfs-tools/hooks/enable-wireless
set -e
PREREQ=""
prereqs()
{
    echo "${PREREQ}"
}
case "${1}" in
    prereqs)
        prereqs
        exit 0
        ;;
esac

. /usr/share/initramfs-tools/hook-functions

# CHANGE HERE for your correct modules.
manual_add_modules wl
copy_exec /sbin/wpa_supplicant
copy_exec /sbin/wpa_cli
copy_exec /sbin/iw
copy_exec /sbin/iwconfig
copy_exec /usr/sbin/haveged
copy_file config /etc/initramfs-tools/wpa_supplicant.conf /etc/wpa_supplicant.conf
copy_file config /lib/crda/regulatory.bin
copy_file config /lib/firmware/regulatory.db
copy_file config /lib/firmware/regulatory.db.p7s

final_commands.sh

# This is run in the shell
sudo chmod +x /etc/initramfs-tools/scripts/local-bottom/kill_wireless.sh
sudo chmod +x /etc/initramfs-tools/scripts/init-premount/a_enable_wireless.sh
sudo chmod +x /etc/initramfs-tools/hooks/enable-wireless.sh

sudo apt install haveged wireless-regdb -y
sudo update-initramfs -k all -c
sudo update-grub

kill_wireless.sh

#!/bin/sh
# this goes into /etc/initramfs-tools/scripts/local-bottom/kill_wireless
PREREQ=""
prereqs()
{
    echo "$PREREQ"
}

case $1 in
prereqs)
    prereqs
    exit 0
    ;;
esac
. /scripts/functions

log_begin_msg "Killing wpa_supplicant so the system takes over later."
kill `cat /run/initram-wpa_supplicant.pid`
log_begin_msg "Killing haveged rngd so the system takes over later."
kill `cat /run/initram-haveged.pid`

wpa_supplicant.conf

# sample /etc/initramfs-tools/wpa_supplicant.conf
# note that this is independent of the system /etc/wpa_supplicant.conf (if any)
# only add the network you need at boot time. **And keep the ctrl_interface** !!
ctrl_interface=/tmp/wpa_supplicant
# Your region should be here
country=US


network={
    ssid="Network 1"
    proto=RSN
    key_mgmt=WPA-PSK
    pairwise=CCMP TKIP
    psk="secret password 1"
    priority=1
}
network={
    ssid="Network 2"
    proto=RSN
    key_mgmt=WPA-PSK
    pairwise=CCMP TKIP
    psk="secret password 2"
    priority=2
}