How to install CentOS 7 remotely using VNC

This time I will discuss on how to install CentOS 7 remotely using VNC. There are some differences between installing CentOS 6 and CentOS 7 remotely via VNC due to different versions of grub.

Basically in CentOS 6 you will find this kind of setup for the menu entry (supposed we have boot partition):

title CentOS 6 VNC Installation
    root (hd0,0)      
    kernel /netinstall/vmlinuz vnc vncpassword=12345678 headless ip=10.0.0.10 gateway=10.0.0.1 netmask=255.255.255.0 dns=10.0.0.5 ksdevice=eth0 method=http://mirror.centos.org/centos/6/os/x86_64/ lang=en_US keymap=us
    initrd /netinstall/initrd.img

What has changed with CentOS 7?

The following table shows the difference of boot options between CentOS 6 and CentOS 7 for VNC installatons:

CentOS 6 CentOS 7
vnc inst.vnc
vncpassword= inst.vncpassword=
Note: MUST at least 8 char
headless inst.headless
ip= ip=ip::gateway:netmask:hostname:interface:none
Example:
ip=10.0.0.10::10.0.0.1:255.255.255.0:host.example.com:eth0:none or ip=dhcp
gateway= See IP above
netmask= See IP above
dns= nameserver=
method= inst.repo=
lang= inst.lang=
keymap= inst.keymap=

You can read the whole options on ⁠CentOS 7 Boot Options.

VNC Installation Configurations

Make sure if you get the right network configurations for IP Address, Gateway, Netmask, and the network device name.

Download the bootstrap files

yum install wget
cd /boot
wget http://mirror.centos.org/centos/7/os/x86_64/isolinux/vmlinuz -O vmlinuz-7
wget http://mirror.centos.org/centos/7/os/x86_64/isolinux/initrd.img -O initrd-7.img

Creating custom menu entry

The safest thing is we just need to copy menu entry that already exists in /boot/grub2/grub.cfg.

Example existing menu entry:

menuentry 'CentOS Linux, with Linux 3.10.0-123.el7.x86_64' --class centos --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-3.10.0-123.el7.x86_64-advanced-ac9e46e0-6de5-4e6f-baf2-cca39dffe49b' {
    load_video
    set gfxpayload=keep
    insmod gzio
    insmod part_msdos
    insmod ext2
    set root='hd0,msdos1'
    if [ x$feature_platform_search_hint = xy ]; then
      search --no-floppy --fs-uuid --set=root --hint='hd0,msdos1'  ac9e46e0-6de5-4e6f-baf2-cca39dffe49b
    else
      search --no-floppy --fs-uuid --set=root ac9e46e0-6de5-4e6f-baf2-cca39dffe49b
    fi
    linux16 /vmlinuz-3.10.0-123.el7.x86_64 root=UUID=ac9e46e0-6de5-4e6f-baf2-cca39dffe49b ro vconsole.keymap=us crashkernel=auto  vconsole.font=latarcyrheb-sun16 rhgb quiet LANG=en_US.UTF-8
    initrd16 /initramfs-3.10.0-123.el7.x86_64.img
}

And than paste it to /etc/grub.d/40_custom. Modify the menu entry title, the linux16, initrd16..

#!/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 'NetInstall' {
    load_video
    set gfxpayload=keep
    insmod gzio
    insmod part_msdos
    insmod ext2
    set root='hd0,msdos1'
    if [ x$feature_platform_search_hint = xy ]; then
      search --no-floppy --fs-uuid --set=root --hint='hd0,msdos1'  ac9e46e0-6de5-4e6f-baf2-cca39dffe49b
    else
      search --no-floppy --fs-uuid --set=root ac9e46e0-6de5-4e6f-baf2-cca39dffe49b
    fi
    linux16 /vmlinuz-7 inst.vnc inst.vncpassword=12345678 inst.headless ip=ip::gateway:netmask::interface:none nameserver=8.8.8.8 inst.repo=http://mirror.centos.org/centos/7/os/x86_64/ inst.lang=en_US inst.keymap=us
    initrd16 /initrd-7.img
}

Note: replace the ip=ip::gateway:netmask::interface:none with yours. eg:

ip=10.0.0.10::10.0.0.1:255.255.255.0::eth0:none

If you are using GPT disk add inst.gpt option.

linux16 /vmlinuz-7 inst.gpt inst.vnc inst.vncpassword=12345678 inst.headless ip=dhcp nameserver=8.8.8.8 inst.repo=http://mirror.centos.org/centos/7/os/x86_64/ inst.lang=en_US inst.keymap=us

Grub configurations

Make sure it only boot our custom menu entry once. In /etc/default/grub, change GRUB_DEFAULT=0 to GRUB_DEFAULT=saved

GRUB_DEFAULT=saved

Save all the configurations.

# rebuilt the grub.cfg

grub2-mkconfig -o /boot/grub2/grub.cfg

# list available menu entry

awk -F\' '$1=="menuentry " {print $2}' /etc/grub2.cfg

# verify the default menu entry.
# you can use grub2-set-default 'MenuEntry' 
# to change the default boot

grub2-editenv list

# boot our new menu entry for the next reboot. 
# We just need to use the menu entry title.

grub2-reboot NetInstall

Double check your current configurations before rebooting your server.

Wait a moments until the setup finished. You can starting your CentOS 7 remote installatons at YOURIP:1 by using VNC.

Note: If the VNC installation not loaded after a few minutes you just need to reboot your server to booting the default menu entry.


Author: danpros

A self-proclaimed geek, business owner, and part-time blogger.

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