Tools/Linux_reinstall/RedHat/RHELinit.sh

#!/bin/ash
#
# Alpine Linux use "ash" as the default shell.

exec >/dev/tty0 2>&1

# Delete the initial script itself to prevent to be executed in the new system.
rm -f /etc/local.d/rhelConf.start
rm -f /etc/runlevels/default/local

# Install necessary components.
apk update
apk add coreutils grep sed

# Get RHEL Linux configurations.
confFile='/root/alpine.config'
cloudInitFile='/mnt/etc/cloud/cloud.cfg.d/99-fake_cloud.cfg'

# Read configs from initial file.
IncDisk=$(grep "IncDisk" $confFile | awk '{print $2}')
LinuxMirror=$(grep -w "LinuxMirror" $confFile | awk '{print $2}')
alpineVer=$(grep "alpineVer" $confFile | awk '{print $2}')
TimeZone1=$(grep "TimeZone" $confFile | awk '{print $2}' | cut -d'/' -f 1)
TimeZone2=$(grep "TimeZone" $confFile | awk '{print $2}' | cut -d'/' -f 2)
tmpWORD=$(grep -w "tmpWORD" $confFile | awk '{print $2}')
sshPORT=$(grep "sshPORT" $confFile | awk '{print $2}')
networkAdapter=$(grep "networkAdapter" $confFile | awk '{print $2}')
IPv4=$(grep "IPv4" $confFile | awk '{print $2}')
MASK=$(grep "MASK" $confFile | awk '{print $2}')
ipPrefix=$(grep "ipPrefix" $confFile | awk '{print $2}')
actualIp4Prefix=$(grep "actualIp4Prefix" $confFile | awk '{print $2}')
GATE=$(grep "GATE" $confFile | awk '{print $2}')
ipDNS1=$(grep "ipDNS1" $confFile | awk '{print $2}')
ipDNS2=$(grep "ipDNS2" $confFile | awk '{print $2}')
iAddrNum=$(grep "iAddrNum" $confFile | awk '{print $2}')
writeIpsCmd=$(grep "writeIpsCmd" $confFile | awk '{print $2}')
ip6Addr=$(grep "ip6Addr" $confFile | awk '{print $2}')
ip6Mask=$(grep "ip6Mask" $confFile | awk '{print $2}')
actualIp6Prefix=$(grep "actualIp6Prefix" $confFile | awk '{print $2}')
ip6Gate=$(grep "ip6Gate" $confFile | awk '{print $2}')
ip6DNS1=$(grep "ip6DNS1" $confFile | awk '{print $2}')
ip6DNS2=$(grep "ip6DNS2" $confFile | awk '{print $2}')
i6AddrNum=$(grep "i6AddrNum" $confFile | awk '{print $2}')
writeIp6sCmd=$(grep "writeIp6sCmd" $confFile | awk '{print $2}')
setIPv6=$(grep "setIPv6" $confFile | awk '{print $2}')
HostName=$(grep "HostName" $confFile | awk '{print $2}')
DDURL=$(grep "DDURL" $confFile | awk '{print $2}')
DEC_CMD=$(grep "DEC_CMD" $confFile | awk '{print $2}')
cloudInitUrl=$(grep "cloudInitUrl" $confFile | awk '{print $2}')
RedHatSeries=$(grep "RedHatSeries" $confFile | awk '{print $2}')
lowMemMode=$(grep "lowMemMode" $confFile | awk '{print $2}')

# Reset configurations of repositories.
true >/etc/apk/repositories
setup-apkrepos $LinuxMirror/$alpineVer/main
setup-apkcache /var/cache/apk

# Add community mirror.
sed -i '$a\'$LinuxMirror'/'$alpineVer'/community' /etc/apk/repositories
# Add edge testing to the repositories
# sed -i '$a\'$LinuxMirror'/edge/testing' /etc/apk/repositories

# Synchronize time from hardware.
hwclock -s

# Install necessary components.
apk update
apk add hdparm multipath-tools util-linux wget xz

# Start dd.
wget --no-check-certificate --report-speed=bits --tries=0 --timeout=10 --wait=5 -O- "$DDURL" | $DEC_CMD | dd of="$IncDisk" status=progress

# Get valid loop device.
loopDevice=$(echo $(losetup -f))
loopDeviceNum=$(echo $(losetup -f) | cut -d'/' -f 3)

# Make a soft link between valid loop device and disk.
losetup $loopDevice $IncDisk

# Get mapper partition.
mapperDevice=$(kpartx -av $loopDevice | grep "$loopDeviceNum" | sort -rn | sed -n '1p' | awk '{print $3}')

# Mount RHEL dd partition to /mnt .
mount /dev/mapper/$mapperDevice /mnt

# Download cloud init file.
wget --no-check-certificate -qO $cloudInitFile ''$cloudInitUrl''

# User config.
sed -ri 's/HostName/'${HostName}'/g' $cloudInitFile
sed -ri 's/tmpWORD/'${tmpWORD}'/g' $cloudInitFile
sed -ri 's/sshPORT/'${sshPORT}'/g' $cloudInitFile
sed -ri 's/TimeZone/'${TimeZone1}'\/'${TimeZone2}'/g' $cloudInitFile
sed -ri 's/networkAdapter/'${networkAdapter}'/g' $cloudInitFile
if [[ "$iAddrNum" -ge "2" ]]; then
  sed -ri 's#IPv4/ipPrefix#'${writeIpsCmd}'#g' $cloudInitFile
else
  sed -ri 's/IPv4/'${IPv4}'/g' $cloudInitFile
  sed -ri 's/ipPrefix/'${ipPrefix}'/g' $cloudInitFile
  sed -ri "s/${IPv4}\/${ipPrefix}/${IPv4}\/${actualIp4Prefix}/g" $cloudInitFile
fi
sed -ri 's/GATE/'${GATE}'/g' $cloudInitFile
sed -ri 's/ipDNS1/'${ipDNS1}'/g' $cloudInitFile
sed -ri 's/ipDNS2/'${ipDNS2}'/g' $cloudInitFile
if [[ "$i6AddrNum" -ge "2" ]]; then
  sed -ri 's#ip6Addr/ip6Mask#'${writeIp6sCmd}'#g' $cloudInitFile
else
  sed -ri 's/ip6Addr/'${ip6Addr}'/g' $cloudInitFile
  sed -ri 's/ip6Mask/'${ip6Mask}'/g' $cloudInitFile
  sed -ri "s/${ip6Addr}\/${ip6Mask}/${ip6Addr}\/${actualIp6Prefix}/g" $cloudInitFile
fi
sed -ri 's/ip6Gate/'${ip6Gate}'/g' $cloudInitFile
sed -ri 's/ip6DNS1/'${ip6DNS1}'/g' $cloudInitFile
sed -ri 's/ip6DNS2/'${ip6DNS2}'/g' $cloudInitFile

# Disable SELinux permanently.
sed -ri 's/^SELINUX=.*/SELINUX=disabled/g' /mnt/etc/selinux/config

# Disable IPv6.
[[ "$setIPv6" == "0" ]] && sed -ri 's/net.ifnames=0 biosdevname=0/net.ifnames=0 biosdevname=0 ipv6.disable=1/g' /mnt/etc/default/grub

# Permit root user login by password, change ssh port.
sed -ri 's/^#?PermitRootLogin.*/PermitRootLogin yes/g' /mnt/etc/ssh/sshd_config
sed -ri 's/^#?PasswordAuthentication.*/PasswordAuthentication yes/g' /mnt/etc/ssh/sshd_config
sed -ri 's/^#?Port.*/Port '${sshPORT}'/g' /mnt/etc/ssh/sshd_config

# Disable allocate swap.
# Note: Swap allowcation in "runcmd" stage during execution of Cloud Init on aarch64 CPU architecture would cause a fatal because of "cloud-final.service" runs failed.
[[ "$lowMemMode" != "1" ]] && sed -i '/swapspace/d' $cloudInitFile

# Hack cloud init.
# Note: this trick has a great effect on Ubuntu 20.04+, AlmaLinux / Rocky 9+ in almost any cloud platforms but unfortunately it 
# is not suitable for Rocky 8 otherwise cloud init will meet a fatal may because of the lower version of python3.6(others are 3.9).
# More details: https://github.com/leitbogioro/Tools/blob/master/Linux_reinstall/Ubuntu/ubuntuInit.sh
[[ "$RedHatSeries" -ge "9" ]] && {
  utilProgram=$(find /mnt/usr/lib/python* -name "util.py" | grep "cloudinit" | head -n 1)
  sed -ri 's/iso9660/osi9876/g' $utilProgram
  sed -ri 's#"blkid"#"echo"#g' $utilProgram
}

# Umount mounted directory and loop device.
umount /mnt
kpartx -dv $loopDevice
losetup -d $loopDevice

# Reboot, the temporary intermediary system of AlpineLinux which is executing in memory will be destroyed during the power down and then server will reboot to the newly system immediately.
exec reboot