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Testing Red Hat Enterprise Linux 7 and CentOS 7 (preview)

Last week, Red Hat released the final version of Red Hat Enterprise Linux version 7. A few days later the CentOS project made a first preview version of CentOS 7 available. Since many of our customers are running on RHEL 6 and/or CentOS 6, now was a good time to look into the newly release 7.0 version.

Both the CentOS-7 and RHEL-7 installations completed without any problems, something that was still giving more then enough issues during the beta and release-candidate stages of RHEL-7. We tested the ‘default’ graphical install, the text-based install and kickstart installs in both graphical and text-modes. Currently we’re fine-tuning our kickstart configuration for the 7 releases, so installs can be fully automated and fast.

Kickstart Configuration

At this time, our kickstart looks somewhat like this (censored to protect sensitive data):

#version=RHEL7
# System authorization information
auth --enableshadow --passalgo=sha512

# Use network installation
url --url="http://buildlogs.centos.org/centos/7/os/x86_64-20140614/"
# Use text mode install
text
# Keyboard layouts
keyboard --vckeymap=us --xlayouts='us'
# System language
lang en_US.UTF-8

# Network information
network  --bootproto=dhcp --device=eth0 --ipv6=auto --activate
network  --hostname=centos7previewkickstarttest
# Root password
rootpw some-password
# Do not configure the X Window System
skipx
# System timezone
timezone Europe/Amsterdam --isUtc
#user --groups=wheel --name=useraccount --password=some-password --gecos="User"
# Skip EULA
eula --agreed
# Disable firewall
firewall --disabled
# Don't run the Setup Agent on first boot
firstboot --disabled
# Selinux (ENFORCING|permissive|disabled)
selinux --enforcing
# Reboot the machine when the installation is finished, eject CD
reboot --eject
# Enable SSH services
services --enabled sshd
# Include auto-generated disk-config
%include /tmp/include.me

%packages
# Core and base are default, just specify them anyway to make this clear
# Then unselect the 'default' marked packages from core and base, which we don't need
%packages
@core
@base
# default from core
-aic94xx-firmware
-alsa-firmware
-bfa-firmware
-dracut-config-rescue
-ivtv-firmware
-iwl1000-firmware
-iwl100-firmware
-iwl105-firmware
-iwl135-firmware
-iwl2000-firmware
-iwl2030-firmware
-iwl3160-firmware
-iwl3945-firmware
-iwl4965-firmware
-iwl5000-firmware
-iwl5150-firmware
-iwl6000-firmware
-iwl6000g2a-firmware
-iwl6000g2b-firmware
-iwl6050-firmware
-iwl7260-firmware
-kernel-tools
-libertas-sd8686-firmware
-libertas-sd8787-firmware
-libertas-usb8388-firmware
-microcode_ctl
-NetworkManager
-NetworkManager-tui
-ql2100-firmware
-ql2200-firmware
-ql23xx-firmware
postfix
linux-firmware
# default from base
-abrt-addon-ccpp
-abrt-addon-python
-abrt-cli
-abrt-console-notification
bash-completion
-blktrace
bridge-utils
bzip2
chrony
-cryptsetup
-dmraid
-dosfstools
ethtool
-fprintd-pam
-gnupg2
-hunspell-en
-hunspell
-kpatch
-ledmon
-libaio
-libreport-plugin-mailx
-libstoragemgmt
lvm2
man-pages-overrides
man-pages
mdadm
mlocate
mtr
nano
ntpdate
-pinfo
-plymouth
pm-utils
-rdate
-rfkill
rng-tools
rsync
-scl-utils
-setuptool
smartmontools
-sos
-sssd-client
strace
sysstat
-systemtap-runtime
tcpdump
-tcsh
-teamd
time
unzip
usbutils
vim-enhanced
virt-what
wget
which
-words
xfsdump
xz
-yum-langpacks
-yum-plugin-security
yum-utils
zip
acpid
redhat-lsb-core
%end

%pre
#!/bin/bash

# Check physical and virtio disks
for disk in /sys/block/sd* /sys/block/vd*
do
        dsk=$(basename $disk)

        if [[ `cat $disk/ro` -eq 1 ]];
        then
                echo "Skipping disk $dsk: READONLY"
                continue;
        fi

        if [[ `cat $disk/removable` -eq 1 ]];
        then
                echo "Skipping disk $dsk: REMOVABLE"
                continue;
        fi

        if [[ `cat $disk/size` -lt 20971520 ]];
        then
                echo "Skipping disk $dsk: Smaller then 10G"
                continue;
        else
                echo "Using disk $dsk"
                chosen=$dsk;
                break;
        fi
done

incfile=/tmp/include.me
> $incfile

if [[ -n $chosen ]];
then
        echo "zerombr" >> $incfile
        echo "bootloader --location=mbr --driveorder=$chosen --append=\"nomodeset console=tty0 console=ttyS0,115200n8\"" >> $incfile
        echo "ignoredisk --only-use=$chosen" >> $incfile
        echo "clearpart --all --initlabel --drives=$chosen" >> $incfile
        echo "part /boot --fstype=ext3 --asprimary --size=256" >> $incfile
        echo "part pv.$chosen --grow --size=15000" >> $incfile
        echo "volgroup vg00 --pesize=32768 pv.$chosen" >> $incfile
        echo "logvol / --fstype=xfs --name=root --vgname=vg00 --size=4096" >> $incfile
        echo "logvol swap --name=swap --vgname=vg00 --size=256" >> $incfile
else
        echo "" > $incfile
fi

%end

# PostInstall stuff
%post --log=/root/anaconda-postinstall.log
#!/bin/sh
cd /
echo "GRUB_TERMINAL=\"serial console\"" >> /etc/default/grub
echo "GRUB_TERMINAL_OUTPUT=\"serial console\"" >> /etc/default/grub
echo "GRUB_SERIAL_COMMAND=\"serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1\"" >> /etc/default/grub

echo "#!/bin/sh" > /usr/local/sbin/update-grub
echo "grub2-mkconfig -o /boot/grub2/grub.cfg" >> /usr/local/sbin/update-grub
chmod +x /usr/local/sbin/update-grub

/usr/local/sbin/update-grub

echo "[base-c7-preview]" > /etc/yum.repos.d/c7-preview.repo
echo "name=CentOS-7-Preview" >> /etc/yum.repos.d/c7-preview.repo
echo "baseurl=http://buildlogs.centos.org/centos/7/os/x86_64-20140614/" >> /etc/yum.repos.d/c7-preview.repo
echo "enabled=1" >> /etc/yum.repos.d/c7-preview.repo
echo "gpgcheck=0" >> /etc/yum.repos.d/c7-preview.repo
%end

This kickstart configuration will try to install a minimal CentOS 7 (preview) system, on the first available disk that is non-removable and bigger then 10GB. It will use LVM and create a 4GB root filesystem, leaving the remaining diskspace free for later use.

It will also configure grub to react on serial input and the vga console, and also configure the kernel and getty’s to work on both serial and vga consoles. It will configure the centos7-preview repository, so installing extra software should be easy. The current install is optimized for virtual machines, and doesn’t install anything related to sound, wifi, network-manager etc.

The entire install will end up being about 840MB, and includes all requirements for running ansible playbooks, so ansible can be used to further configure the system after initial installation.

Most notable changes

The major changes that you will run into, if you are used to CentOS/RHEL 5 and 6 are:

  • Systemd is now used as init system, with all required changes that come with it
  • BTRFS and XFS are supported, and the system can use either as a root filesystem (xfs was available in centos/redhat 6, but not usable as root or boot filesystem)
  • On installs with X and a desktop, you will now get a Gnome 3 Classic based desktop. Luckily a tweak-tool is available and installed by default, which will allow you to tune the desktop somewhat.

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