通过新增系统启动项来原地重装操作系统

很多时候，我们有一台centos7的主机，但是没有cd-rom的访问权限，有可能也没有console的访问权限，而我们做实验，又需要把这个主机刷新成rhel8等操作系统，那么我们怎么才能把这个centos7主机，原地重新安装成其他操作系统呢？

之前，已经有文章，描述怎么从centos7开始一个openshift/coreos的安装。那么，本文就探讨一下，如何从centos7，自动化安装一个alma8。同时，为了探索在安装的时候，能加载某些第三方驱动，我们也试试如何从centos7 boot进入alma8的手动安装界面。

boot into auto install

我们先来做一个从centos7的系统，做一些配置以后，重启，自动化安装成alma8系统。

这个部署就是一个kvm，这个kvm原来装的是centos7。但是我们需要一个安装源，也就是一个外部的http web server，提供安装光盘，并且提供kickstart配置文件。按理说哈，我们是可以配置kvm，把这些安装光盘里面的文件，还有kickstart文件什么的，都放到本地硬盘里面去，但是无奈在启动参数里面，你要指定这个硬盘id，作者实在是不知道怎么找到这些硬盘id，好在如果你用外部的http web server，只要知道URL就可以。

参考资料：

• https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html-single/system_design_guide/index#starting-a-kickstart-installation-manually_starting-kickstart-installations
• https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html-single/system_design_guide/index#updating-drivers-during-installation_system-design-guide
• https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html-single/system_design_guide/index#updating-drivers-during-installation_system-design-guide

# create a kickstart file and copy to /data/dnf/
# 本文的目录里面，有kickstart的配置模板，我们改变一下里面的IP地址i配置，安装源的URL就能用了。
sed -i '0,/^network.*/s/^network.*/network  --bootproto=static --device=enp1s0 --gateway=192.168.7.11 --ip=192.168.7.12  --netmask=255.255.255.0 --nameserver=192.168.7.11  --ipv6=auto --activate/' helper-ks-alma.cfg

sed -i '0,/^url --url.*/s/^url --url.*/url --url="http:\/\/192.168.7.11:5000\/cdrom\/"/' helper-ks-alma.cfg

# create a centos7 kvm

# 要装kvm，我们需要一个bridge
cat << 'EOF' > /data/kvm/bridge.sh
#!/usr/bin/env bash

PUB_CONN='eno1'
PUB_IP='172.21.6.102/24'
PUB_GW='172.21.6.254'
PUB_DNS='172.21.1.1'

nmcli con down "$PUB_CONN"
nmcli con delete "$PUB_CONN"
nmcli con down baremetal
nmcli con delete baremetal
# RHEL 8.1 appends the word "System" in front of the connection,delete in case it exists
nmcli con down "System $PUB_CONN"
nmcli con delete "System $PUB_CONN"
nmcli connection add ifname baremetal type bridge con-name baremetal ipv4.method 'manual' \
    ipv4.address "$PUB_IP" \
    ipv4.gateway "$PUB_GW" \
    ipv4.dns "$PUB_DNS"
    
nmcli con add type bridge-slave ifname "$PUB_CONN" master baremetal
nmcli con down "$PUB_CONN";pkill dhclient;dhclient baremetal
nmcli con up baremetal
EOF
bash /data/kvm/bridge.sh

nmcli con mod baremetal +ipv4.addresses "192.168.7.102/24"
nmcli con up baremetal

mkdir -p /data/kvm
cd /data/kvm

# 我们就用centos7 minimal iso来安装好了。
# 先下载这个iso，作者发现，南京大学的mirror是真的快啊。。。
wget -O centos.iso http://mirrors.nju.edu.cn/centos/7.9.2009/isos/x86_64/CentOS-7-x86_64-Minimal-2207-02.iso

# 同样，作者提供了一个kvm安装centos的kickstart配置文件模板，替换一下ip地址配置就能用了。
sed -i '0,/^network.*/s/^network.*/network  --bootproto=static --device=eth0 --gateway=192.168.7.9 --ip=192.168.7.12  --netmask=255.255.255.0 --nameserver=192.168.7.11  --ipv6=auto --activate/' helper-ks.cfg

# 接下来，我们定义kvm，给他创建存储空间，启动kvm，就开始自动安装centos kvm了
create_lv() {
    var_vg=$1
    var_pool=$2
    var_lv=$3
    var_size=$4
    var_action=$5
    lvremove -f $var_vg/$var_lv
    # lvcreate -y -L $var_size -n $var_lv $var_vg
    if [ "$var_action" == "recreate" ]; then
      lvcreate --type thin -n $var_lv -V $var_size --thinpool $var_vg/$var_pool
      wipefs --all --force /dev/$var_vg/$var_lv
    fi
}

virsh destroy ocp4-acm-hub
virsh undefine ocp4-acm-hub

create_lv vgdata poolA lvacmhub 100G 
create_lv vgdata poolA lvacmhub-data 100G 

create_lv vgdata poolA lvacmhub 100G recreate
create_lv vgdata poolA lvacmhub-data 100G recreate

virt-install --name="ocp4-acm-hub" --vcpus=16 --ram=$((4*1024)) \
    --cpu=host-model \
    --disk path=/dev/vgdata/lvacmhub,device=disk,bus=virtio,format=raw \
    --disk path=/dev/vgdata/lvacmhub-data,device=disk,bus=virtio,format=raw \
    --os-variant rhel8.5 --network bridge=baremetal,model=virtio \
    --graphics vnc,port=59000 \
    --boot menu=on --location /data/kvm/centos.iso \
    --initrd-inject helper-ks.cfg --extra-args "inst.ks=file:/helper-ks.cfg" 

# 等一会，我们就有了一个centos kvm了。

# on helper web server
# 然后，我们在web server上，下载alma8的安装光盘，我们用minimal的版本就好了。
cd /data/dnf
wget -O alma8.iso http://mirrors.nju.edu.cn/almalinux/8/isos/x86_64/AlmaLinux-8-latest-x86_64-minimal.iso
# wget -O rocky8.iso http://mirrors.nju.edu.cn/rocky/8/isos/x86_64/Rocky-x86_64-minimal.iso

# 我们把光盘挂载在本地，然后我们的web server会自动的发布出去。
mkdir -p /data/dnf/cdrom
mount alma8.iso /data/dnf/cdrom
# mount rocky8.iso /data/dnf/cdrom

# on the centos7 vm
# 登录到新安装的centos7， 修改启动项，让下次启动的时候，直接进入安装界面
sshpass -p 'redhat' ssh-copy-id root@192.168.7.12

ssh root@192.168.7.12

# 在centos7里面，下载alma8的内核和ram disk.
HELPER_URL=http://192.168.7.11:5000/cdrom/

curl -o /boot/initrd.img  $HELPER_URL/images/pxeboot/initrd.img
curl -o /boot/vmlinuz     $HELPER_URL/images/pxeboot/vmlinuz

SNO_IP=192.168.7.13
SNO_GW=192.168.7.11
SNO_NETMAST=255.255.255.0
SNO_HOSTNAME=acm-demo-hub-master
SNO_IF=enp1s0
SNO_DNS=192.168.7.11
SNO_DISK=/dev/vda
SNO_ROOTFS=http://192.168.7.11:5000/cdrom/
SNO_IGN=http://192.168.7.11:5000/helper-ks-alma.cfg

# 根据参数，我们自定义一个启动项，
# 这个启动项，用alma8的内核和ram disk启动，带IP地址参数，
# kickstart配置文件指向web server, 安装文件源也指向web server
cat << EOF > /etc/grub.d/40_custom
#!/bin/sh
exec tail -n +3 \$0
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.

menuentry 'coreos' --class fedora --class gnu-linux --class gnu --class os {
    insmod gzio
    insmod part_msdos
    insmod xfs
    set root='hd0,msdos1'
    echo  'Loading coreos kernel ...'
    linux /vmlinuz rd.neednet=1 ip=$SNO_IP::$SNO_GW:$SNO_NETMAST:$SNO_HOSTNAME:$SNO_IF:none nameserver=$SNO_DNS  inst.ks=$SNO_IGN inst.repo=$SNO_ROOTFS
    echo  'Loading coreos initrd ...'
    initrd /initrd.img
}
EOF

# 定义下次自动启动的启动项，就是我们新定义
sed -i 's/^GRUB_DEFAULT=.*/GRUB_DEFAULT="coreos"/' /etc/default/grub 

# 写入我们的配置到grub
grub2-mkconfig -o /etc/grub2.cfg

# 重启等待就好了。
reboot

boot into install console

有的时候，我们是能接触到console的，而且自动化配置的很多参数，我们也不知道，那么我们就必须用手动的方式安装。同样的，我们假设设备已经装好了centos7，我们从这里开始开始。

这里面的区别和上面的步骤很小，就是在启动参数里面，我们不要加inst.ks这个参数，也就是没有自动化安装的配置文件，这样重启以后，我们就能停留在我们很熟悉的安装界面上了。

# create a centos7 kvm

cat << 'EOF' > /data/kvm/bridge.sh
#!/usr/bin/env bash

PUB_CONN='eno1'
PUB_IP='172.21.6.102/24'
PUB_GW='172.21.6.254'
PUB_DNS='172.21.1.1'

nmcli con down "$PUB_CONN"
nmcli con delete "$PUB_CONN"
nmcli con down baremetal
nmcli con delete baremetal
# RHEL 8.1 appends the word "System" in front of the connection,delete in case it exists
nmcli con down "System $PUB_CONN"
nmcli con delete "System $PUB_CONN"
nmcli connection add ifname baremetal type bridge con-name baremetal ipv4.method 'manual' \
    ipv4.address "$PUB_IP" \
    ipv4.gateway "$PUB_GW" \
    ipv4.dns "$PUB_DNS"
    
nmcli con add type bridge-slave ifname "$PUB_CONN" master baremetal
nmcli con down "$PUB_CONN";pkill dhclient;dhclient baremetal
nmcli con up baremetal
EOF
bash /data/kvm/bridge.sh

nmcli con mod baremetal +ipv4.addresses "192.168.7.102/24"
nmcli con up baremetal


mkdir -p /data/kvm
cd /data/kvm

wget -O centos.iso http://mirrors.nju.edu.cn/centos/7.9.2009/isos/x86_64/CentOS-7-x86_64-Minimal-2207-02.iso

sed -i '0,/^network.*/s/^network.*/network  --bootproto=static --device=eth0 --gateway=192.168.7.9 --ip=192.168.7.12  --netmask=255.255.255.0 --nameserver=192.168.7.11  --ipv6=auto --activate/' helper-ks.cfg


create_lv() {
    var_vg=$1
    var_pool=$2
    var_lv=$3
    var_size=$4
    var_action=$5
    lvremove -f $var_vg/$var_lv
    # lvcreate -y -L $var_size -n $var_lv $var_vg
    if [ "$var_action" == "recreate" ]; then
      lvcreate --type thin -n $var_lv -V $var_size --thinpool $var_vg/$var_pool
      wipefs --all --force /dev/$var_vg/$var_lv
    fi
}

virsh destroy ocp4-acm-hub
virsh undefine ocp4-acm-hub

create_lv vgdata poolA lvacmhub 100G 
create_lv vgdata poolA lvacmhub-data 100G 


create_lv vgdata poolA lvacmhub 100G recreate
create_lv vgdata poolA lvacmhub-data 100G recreate


virt-install --name="ocp4-acm-hub" --vcpus=16 --ram=$((4*1024)) \
    --cpu=host-model \
    --disk path=/dev/vgdata/lvacmhub,device=disk,bus=virtio,format=raw \
    --disk path=/dev/vgdata/lvacmhub-data,device=disk,bus=virtio,format=raw \
    --os-variant rhel8.5 --network bridge=baremetal,model=virtio \
    --graphics vnc,port=59000 \
    --boot menu=on --location /data/kvm/centos.iso \
    --initrd-inject helper-ks.cfg --extra-args "inst.ks=file:/helper-ks.cfg" 

# on helper web server
cd /data/dnf
wget -O alma8.iso http://mirrors.nju.edu.cn/almalinux/8/isos/x86_64/AlmaLinux-8-latest-x86_64-minimal.iso

mkdir -p /data/dnf/cdrom
mount alma8.iso /data/dnf/cdrom

# on the centos7 vm
sshpass -p 'redhat' ssh-copy-id root@192.168.7.12

ssh root@192.168.7.12

HELPER_URL=http://192.168.7.11:5000/cdrom/

curl -o /boot/initrd.img  $HELPER_URL/images/pxeboot/initrd.img
curl -o /boot/vmlinuz     $HELPER_URL/images/pxeboot/vmlinuz

SNO_IP=192.168.7.12
SNO_GW=192.168.7.11
SNO_NETMAST=255.255.255.0
SNO_HOSTNAME=acm-demo-hub-master
SNO_IF=enp1s0
SNO_DNS=192.168.7.11
SNO_DISK=/dev/vda
SNO_ROOTFS=http://192.168.7.11:5000/cdrom/
SNO_IGN=http://192.168.7.11:5000/helper-ks-alma8.cfg


cat << EOF > /etc/grub.d/40_custom
#!/bin/sh
exec tail -n +3 \$0
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.

menuentry 'coreos' --class fedora --class gnu-linux --class gnu --class os {
    insmod gzio
    insmod part_msdos
    insmod xfs
    set root='hd0,msdos1'
    echo  'Loading coreos kernel ...'
    linux /vmlinuz rd.neednet=1 ip=$SNO_IP::$SNO_GW:$SNO_NETMAST:$SNO_HOSTNAME:$SNO_IF:none nameserver=$SNO_DNS inst.repo=$SNO_ROOTFS
    echo  'Loading coreos initrd ...'
    initrd /initrd.img 
}
EOF

sed -i 's/^GRUB_DEFAULT=.*/GRUB_DEFAULT="coreos"/' /etc/default/grub 

grub2-mkconfig -o /etc/grub2.cfg

reboot

build nano boot disk

我们尝试做一个迷你启动盘，在这个迷你启动盘里面，除了内核和ram disk之外，什么也没有。同时，增加内核参数，把安装介质和kickstart配置文件，都指向web server。

• https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html-single/installation_guide/index#s2-kickstart2-boot-media

dnf install -y isomd5sum

cd /data/dnf

wget -O rocky8.iso http://mirrors.nju.edu.cn/rocky/8/isos/x86_64/Rocky-x86_64-minimal.iso
mount rocky8.iso /data/dnf/cdrom

# create a kickstart file and copy to /data/dnf/
# 本文的目录里面，有kickstart的配置模板，我们改变一下里面的IP地址i配置，安装源的URL就能用了。
cd /data/dnf
/bin/cp -f helper-ks-alma.cfg helper-ks-alma-wutong.cfg

# for 101
SNO_IP=172.21.6.101
SNO_IP_INSTALL=172.21.6.199
SNO_GW=172.21.6.254
SNO_NETMAST=255.255.255.0
SNO_HOSTNAME=panlab-101
SNO_IF=eno1
SNO_DNS=172.21.1.1
SNO_DISK=/dev/sda
SNO_ROOTFS=http://172.21.6.11:5000/cdrom/
SNO_IGN=http://172.21.6.11:5000/helper-ks-alma-wutong.cfg

# for 102
SNO_IP=172.21.6.102
SNO_IP_INSTALL=172.21.6.199
SNO_GW=172.21.6.254
SNO_NETMAST=255.255.255.0
SNO_HOSTNAME=panlab-102
SNO_IF=eno1
SNO_DNS=172.21.1.1
SNO_DISK=/dev/sda
SNO_ROOTFS=http://172.21.6.11:5000/cdrom/
SNO_IGN=http://172.21.6.11:5000/helper-ks-alma-wutong.cfg

# for 103
SNO_IP=172.21.6.103
SNO_IP_INSTALL=172.21.6.199
SNO_GW=172.21.6.254
SNO_NETMAST=255.255.255.0
SNO_HOSTNAME=panlab-102
SNO_IF=eno1
SNO_DNS=172.21.1.1
SNO_DISK=/dev/sda
SNO_ROOTFS=http://172.21.6.11:5000/cdrom/
SNO_IGN=http://172.21.6.11:5000/helper-ks-alma-wutong.cfg


sed -i "0,/^network.*/s/^network.*/network  --bootproto=static --device=$SNO_IF --gateway=$SNO_GW --ip=$SNO_IP  --netmask=$SNO_NETMAST --nameserver=$SNO_DNS  --ipv6=auto --activate/" helper-ks-alma-wutong.cfg
sed -i "s/network  --hostname=.*/network  --hostname=$SNO_HOSTNAME/" helper-ks-alma-wutong.cfg

sed -i "0,/^url --url.*/s#^url --url.*#url --url=\"$SNO_ROOTFS\"#" helper-ks-alma-wutong.cfg

sed -i 's/vda/sda/g' helper-ks-alma-wutong.cfg


# mount /data/dnf/alma8.iso /data/dnf/cdrom

mkdir -p /data/tmp/

/bin/cp -pRf /data/dnf/cdrom/ /data/tmp/

cd /data/tmp/cdrom

rm -rf BaseOS/
rm -rf Minimal/
rm -f images/install.img

cat <<EOF > isolinux/isolinux.cfg
default vesamenu.c32
timeout 5

display boot.msg

# Clear the screen when exiting the menu, instead of leaving the menu displayed.
# For vesamenu, this means the graphical background is still displayed without
# the menu itself for as long as the screen remains in graphics mode.
menu clear
menu background splash.png
menu title AlmaLinux 8.7
menu vshift 8
menu rows 18
menu margin 8
#menu hidden
menu helpmsgrow 15
menu tabmsgrow 13

# Border Area
menu color border * #00000000 #00000000 none

# Selected item
menu color sel 0 #ffffffff #00000000 none

# Title bar
menu color title 0 #ff7ba3d0 #00000000 none

# Press [Tab] message
menu color tabmsg 0 #ff3a6496 #00000000 none

# Unselected menu item
menu color unsel 0 #84b8ffff #00000000 none

# Selected hotkey
menu color hotsel 0 #84b8ffff #00000000 none

# Unselected hotkey
menu color hotkey 0 #ffffffff #00000000 none

# Help text
menu color help 0 #ffffffff #00000000 none

# A scrollbar of some type? Not sure.
menu color scrollbar 0 #ffffffff #ff355594 none

# Timeout msg
menu color timeout 0 #ffffffff #00000000 none
menu color timeout_msg 0 #ffffffff #00000000 none

# Command prompt text
menu color cmdmark 0 #84b8ffff #00000000 none
menu color cmdline 0 #ffffffff #00000000 none

# Do not display the actual menu unless the user presses a key. All that is displayed is a timeout message.

menu tabmsg Press Tab for full configuration options on menu items.

menu separator # insert an empty line
menu separator # insert an empty line

label linux
  menu label ^Install WZH Linux 8.7
  menu default
  kernel vmlinuz
  append initrd=initrd.img rd.neednet=1 ip=$SNO_IP_INSTALL::$SNO_GW:$SNO_NETMAST:$SNO_HOSTNAME:$SNO_IF:none nameserver=$SNO_DNS  inst.ks=$SNO_IGN inst.repo=$SNO_ROOTFS

label check
  menu label Test this ^media & install WZH Linux 8.7
  kernel vmlinuz
  append initrd=initrd.img inst.stage2=hd:LABEL=AlmaLinux-8-7-x86_64-dvd rd.live.check quiet

menu separator # insert an empty line

# utilities submenu
menu begin ^Troubleshooting
  menu title Troubleshooting

label vesa
  menu indent count 5
  menu label Install AlmaLinux 8.7 in ^basic graphics mode
  text help
        Try this option out if you're having trouble installing
        AlmaLinux 8.7.
  endtext
  kernel vmlinuz
  append initrd=initrd.img inst.stage2=hd:LABEL=AlmaLinux-8-7-x86_64-dvd nomodeset quiet

label rescue
  menu indent count 5
  menu label ^Rescue a AlmaLinux system
  text help
        If the system will not boot, this lets you access files
        and edit config files to try to get it booting again.
  endtext
  kernel vmlinuz
  append initrd=initrd.img inst.stage2=hd:LABEL=AlmaLinux-8-7-x86_64-dvd inst.rescue quiet

label memtest
  menu label Run a ^memory test
  text help
        If your system is having issues, a problem with your
        system's memory may be the cause. Use this utility to
        see if the memory is working correctly.
  endtext
  kernel memtest

menu separator # insert an empty line

label local
  menu label Boot from ^local drive
  localboot 0xffff

menu separator # insert an empty line
menu separator # insert an empty line

label returntomain
  menu label Return to ^main menu
  menu exit

menu end

EOF


genisoimage -U -r -v -T -J -joliet-long -V "RHEL-6.9" -volset "RHEL-6.9" -A "RHEL-6.9" -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -eltorito-alt-boot -e images/efiboot.img -no-emul-boot -o ../wzh.iso .

implantisomd5 ../wzh.iso

update minimal

dnf update-minimal --security

end

others

https://access.redhat.com/documentation/zh-cn/red_hat_enterprise_linux/7/html/installation_guide/chap-anaconda-boot-options

• inst.graphical
• inst.resolution=800x600

dmsetup info -c -o name,blkdevname,devnos_used,blkdevs_used
# Name                  BlkDevName       DevNosUsed       BlkDevNamesUsed
# vgdata-lvacmhub       dm-4             253:2            dm-2
# vgdata-lvacmhub--data dm-5             253:2            dm-2
# vgdata-poolA          dm-3             253:2            dm-2
# vgdata-poolA-tpool    dm-2             253:1,253:0      dm-1,dm-0
# vgdata-poolA_tdata    dm-1             8:16             sdb
# vgdata-poolA_tmeta    dm-0             8:16             sdb