pxeboot/create_pxeinitrd.sh

#!/bin/bash
set -Eeuxo pipefail

TMP_DIR=${TMP_DIR:=$PWD}
MNT_DIR=$TMP_DIR/newroot
INITRD_DIR=$TMP_DIR/initramfs
RESULT_DIR=$TMP_DIR/files

[[ -d $MNT_DIR ]]    || mkdir -p $MNT_DIR
[[ -d $INITRD_DIR ]] || mkdir -p $INITRD_DIR
[[ -d $RESULT_DIR ]] || mkdir -p $RESULT_DIR

HOSTNAME=localhost
# Configs overwritable via environment variables
RELEASE=${RELEASE:=unstable}
FLAVOUR=${FLAVOUR:=debian}					# Either 'debian' or 'ubuntu'
INCLUDES=${INCLUDES:="openssh-server,init,curl,parted,xz-utils,vim,locales-all,less,dmidecode,iputils-ping,fping,tcpdump,rsync,ethtool,lldpd,iproute2,net-tools,sudo,gnupg,tcpdump,mtr-tiny,ifupdown,ipmitool,iptables,telnet,netcat,bridge-utils,vlan,ifstat,ncurses-term,wget,pciutils,dhcpcd5,python"}
MIRROR=${MIRROR:="https://mirrors.wit.com/debian"}
ARCH=${ARCH:=amd64}


fail() {
	echo ""
	echo "FAILED: $1"
	exit 1
}

cancel() {
	fail "CTRL-C detected"
}

trap cancel INT



if [ $FLAVOUR == "debian" ]; then
    BOOT_PKG="linux-image-$ARCH"
elif [ $FLAVOUR == "ubuntu" ]; then
    BOOT_PKG="linux-image-generic"
fi


###################
## build root fs ##
###################


echo "Installing Debian $RELEASE..."
debootstrap --variant=minbase --include=$INCLUDES,$BOOT_PKG $RELEASE $MNT_DIR $MIRROR || fail "cannot install $RELEASE"

echo $HOSTNAME > $MNT_DIR/etc/hostname

cat <<EOF > $MNT_DIR/etc/hosts
127.0.0.1       localhost
# The following lines are desirable for IPv6 capable hosts
::1     localhost ip6-localhost ip6-loopback
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
EOF

echo "ipv4: \4   ipv6: \6" >>/etc/issue

rm -f $MNT_DIR/etc/apt/sources.list
echo 'deb https://mirrors.wit.com/debian sid main contrib non-free' > $MNT_DIR/etc/apt/sources.list
echo 'deb https://mirrors.wit.com/debcore sid main' >> $MNT_DIR/etc/apt/sources.list
curl https://mirrors.wit.com/debcore/public.key | LANG=C DEBIAN_FRONTEND=noninteractive chroot $MNT_DIR apt-key add -

LANG=C DEBIAN_FRONTEND=noninteractive chroot $MNT_DIR apt-get update
LANG=C DEBIAN_FRONTEND=noninteractive chroot $MNT_DIR apt-get clean

cat /dev/null > $MNT_DIR/etc/machine-id

sed -i '/PasswordAuthentication/d' $MNT_DIR/etc/ssh/sshd_config
echo "PasswordAuthentication no" >>$MNT_DIR/etc/ssh/sshd_config

mkdir -p $MNT_DIR/root/.ssh
echo ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDd7rLlS1NmTpBr5KP5ryuA/euGD8I6uc2RCg4sCIlvH0FhEPb123QuMVImHi23ftVP61cKZXm8MlTtAoLHduYtGMHCkJWAAkiIpPetAP2KPIpuadtgIS8xuD/TCYjl0xNXLh0M1C7i7HOnTd8yr+3QNjUppyDdKjLvMQbPWZZTU5rt7CYoGlrxHjieCkq9jj8kRjRARUaAJ4DHEgMFUDIcq3JYluzzkgPK/JFwoq/IokVQCr5qfQRwr3SCkD4sIuGTj+J67uzabIr/xDBqlrMW3T+7YfY12ciHpijob+l7xESkJ+6Gxh56z8llBkGiVyh3UqnmW4MvfuAA/D3Dzhwr afrank@adams-mbp.lan > $MNT_DIR/root/.ssh/authorized_keys

cat <<EOF > $MNT_DIR/etc/systemd/system/start-me-up.service
[Unit]
Description=WIT System Startup
Wants=network-online.target
After=network-online.target

[Service]
Type=oneshot
ExecStart=/usr/local/bin/start_me_up.sh
RemainAfterExit=true
ExecStop=/usr/local/bin/shut_me_down.sh
StandardOutput=journal

[Install]
WantedBy=multi-user.target
EOF


cat <<EOF > $MNT_DIR/usr/local/bin/start_me_up.sh
#!/bin/bash
eval "kernel_args=( \$(cat /proc/cmdline) )"
for i in "\${kernel_args[@]}"
 do
   if [ \${i:0:4} = exec ]
     then
       export -- "\$i"
   fi
done

echo \$execstartup
eval \$execstartup
EOF


cat <<EOF > $MNT_DIR/usr/local/bin/shut_me_down.sh
#!/bin/bash
eval "kernel_args=( \$(cat /proc/cmdline) )"
for i in "\${kernel_args[@]}"
 do
   if [ \${i:0:4} = exec ]
     then
       export -- "\$i"
   fi
done

echo \$execshutdown
eval \$execshutdown
EOF


cat <<EOF >$MNT_DIR/etc/dhcpcd.conf
hostname
duid
slaac hwaddr
noipv4ll
option domain_name_servers, domain_name, domain_search, host_name
option classless_static_routes, ntp_servers, interface_mtu
require dhcp_server_identifier
EOF


chmod +x $MNT_DIR/usr/local/bin/start_me_up.sh
chmod +x $MNT_DIR/usr/local/bin/shut_me_down.sh

chroot $MNT_DIR systemctl enable start-me-up || fail "failed to enable start-me-up"



#echo "Enter root password:"
#while ! chroot $MNT_DIR passwd root
#do
#	echo "Try again"
#done




##################
## build initrd ##
##################


mkdir -p $INITRD_DIR/bin
wget -O $INITRD_DIR/bin/busybox https://www.busybox.net/downloads/binaries/1.26.1-defconfig-multiarch/busybox-x86_64
chmod +x $INITRD_DIR/bin/busybox

cat <<-"EOF" >$INITRD_DIR/init
		#!/bin/busybox sh
		
		# Dump to sh if something fails
		error() {
		  echo "Jumping into the shell..."
		  setsid cttyhack sh
		}
		
		# Populate /bin with binaries from busybox
		/bin/busybox --install /bin
		
		mkdir -p /proc
		mount -t proc proc /proc
		
		mkdir -p /sys
		mount -t sysfs sysfs /sys
		
		mkdir -p /sys/dev
		mkdir -p /var/run
		mkdir -p /dev
		
		mkdir -p /dev/pts
		mount -t devpts devpts /dev/pts
		
		# Populate /dev
		echo /bin/mdev > /proc/sys/kernel/hotplug
		mdev -s
		
		mkdir -p /newroot
		mount -t tmpfs -o size=${size:=10000}m tmpfs /newroot || error
		
		echo "Extracting rootfs... "
		xz -d -c -f rootfs.tar.xz | tar -x -f - -C /newroot || error
		
		mount --move /sys /newroot/sys
		mount --move /proc /newroot/proc
		mount --move /dev /newroot/dev
		
		exec switch_root /newroot /sbin/init || error
EOF

chmod +x $INITRD_DIR/init

tar -cJf $INITRD_DIR/rootfs.tar.xz -C $MNT_DIR .

cp $MNT_DIR/boot/vmlinuz-* $RESULT_DIR/vmlinuz
cd $INITRD_DIR
find . -print0 | cpio --null -ov --format=newc | gzip -9 > $RESULT_DIR/initramfs.gz


ls -la $RESULT_DIR/



exit 0