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=30
INTERFACE="wlp5s0"
alias WPACLI="/sbin/wpa_cli -p/tmp/wpa_supplicant -i$INTERFACE "

log_begin_msg "Starting WLAN connection"
/sbin/wpa_supplicant  -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
else
  ONLINE=1
  log_success_msg "WLAN online"
fi

configure_networking

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 iwlwifi iwlmvm
copy_exec /sbin/wpa_supplicant
copy_exec /sbin/wpa_cli
copy_file config /etc/initramfs-tools/wpa_supplicant.conf /etc/wpa_supplicant.conf

final_commands.sh

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

update-initramfs -k all -u
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

echo "Killing wpa_supplicant so the system takes over later."
kill `cat /run/initram-wpa_supplicant.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

network={
    ssid="MyNetwork"
    scan_ssid=1
    psk="network passphrase"
    key_mgmt=WPA-PSK
}

2. The resized root partition won't work in another raspberry pi or resized SD card unless you get to boot there from a second USB stick, chroot into the installation with LUKS and rebuild the initramfs. "Cross-initramfs-building" is NOT an option. I learned this the very hard way, that is, time.

It worked well for me, I just had to use QEMU.

It worked well for me, I just had to use QEMU.

I tried to fit a 64gb installation into a 16 gb card (both rsync and resize/dd way). I made sure to use the same UUIDs for the partitions. SSH works on boot, but after entering the passphrase this follows:

Cannot initialize device-mapper. Is dm_mod kernel module loaded?

The same applied to the Pi400. Since I have another installation running on the Pi400, after chrooting and rebuilding it worked there, but rebuilding for the Pi Zero W failed.

Thanks for this scripts.
To add autodetection of wlan interface name in a_enable_wireless.sh
change

INTERFACE="wlp5s0"

to

INTERFACE=`ip link | awk '{if(substr($2,1,1) =="w") {gsub(":","",$2); print($2); exit;}}'`

it finds first interface by mask "w*",
and then add check if INTERFACE is zero string and skip wpa_supplicant.

if ! [ -z "$INTERFACE" ]; then

  # wpa supllicant stuff

fi

configure_networking

Hello, I'm having a little issue. I've tried the above (thanks for the scripts!) but I'm now stuck and not able to boot my server.

I think the connection is failing for some reason except that I never end up again in a command line to unlock my disk manually from the laptop (without using wifi).

Any idea how I can solve this?

Hello, I'm having a little issue. I've tried the above (thanks for the scripts!) but I'm now stuck and not able to boot my server.

You are welcome.

I am not using Debian on this scenarios anymore so I cannot be of much help but:

a) I think there have been some considerable changes to initramfs/dracut that could make all this not very usefull
b) The dropbear packages (dropbear-initramfs), if memory serves well, had some scripts on line with what is proposed here which may be useful.
c) The mandos-client package also had some sample scripts that could help you

Oh, and check the comments posted here by some users giving updates! like @morfikov & @leksmut (Thank you all for those comments!)