InstantVM based on Devuan Excalibur

NOTE: WORK IN PROGRESS - I am writing these as I go through the process, therefore until this notice is removed, they are incomplete / untested.

These notes are for creating a virtual server installed and running the way I like it, in under 2 minutes (time is dependent on the hosting hardware, Internet connection speed, and how many packages have been updated since you created the template).

It's based on the previous notes I wrote when doing this for Chimaera and Daedalus.

1. Create a 3Gbyte partition Excalibur VM and go through the standard Devuan installation process, but do not re-start the server at the end
   • Use DHCP networking on eth0
   • Set the hostname to (literally) MyHostNameGoesHere
   • Leave the domain name blank
   • The root password, the first user and its password, will be replicated on every VM created from this image
   • Select Manual partitioning
     • Create vda1 of as large a size as possible, but leave around 1-2Mbyte free (yes, megabytes) for vda2 - try 3218850Kb as the size for vda1
       • Make vda1 an ext4 partition for /
       • Set vda2 to "do not use" (this should end up in the summary as 1Mbyte)
     • Create vdb1 as swap
   • For a 3 Gbyte root FS, the package selector won't offer a graphical desktop environment, but "SSH server" should be selected by default - this is exactly what you want for a server
   • When the installer wants to restart the machine, pause the Grub menu and then just power off the VM
2. Use ddrescue or similar to take a copy of the resultant disk image, just in case something goes horribly wrong with the next few steps and you need to start again - this saves you going through the entire Devuan installation process again
3. Use kpartx to mount the (as yet never-booted-up) root partition and preserve the pristine /var/log directory, copy some files to be unpacked later, and then adjust some configuration files:

   kpartx -av /dev/VG/VMname
   mount /dev/mapper/VG-VMname1 /mnt
   rsync -Pav fs.Excalibur.tgz /mnt
   cd /mnt
   rsync -Pav var/log/ var/log.pristine
   rm -f etc/apt/sources.list etc/apt/sources.list~
   sed -i "s/export PATH/export PATH\nexport HISTSIZE=10000\nexport HISTFILESIZE=10000\nexport HISTCONTROL=none\nexport HISTTIMEFORMAT=\"%F %T \"\nexport QUOTING_STYLE=literal/" etc/profile
   sed -i "s/sulogin/sulogin -t 30/" etc/init.d/checkfs.sh
   sed -i "s/:root:/:MyHostNameGoesHere:/" etc/passwd
   cd ~
   umount /mnt
   dd if=/dev/zero of=/dev/mapper/VG-VMname2
   kpartx -dv /dev/VG/VMname

   • Note: The fs.Excalibur.tgz file contains:

     etc/apt/apt.conf.d/42norecommendationsplease
     etc/apt/apt.conf.d/42nosuggestionsplease
     etc/apt/sources.list.d/Excalibur.list
     etc/boot.d/firstboot
     etc/cron.midnight/
     etc/cron.midnight/.placeholder
     etc/cron.minutely/
     etc/cron.minutely/.placeholder
     etc/cron.yearly/
     etc/cron.yearly/.placeholder
     etc/cron.daily/backup
     etc/crontab
     etc/fstab
     etc/network/interfaces
     etc/ssh/ssh_config.d/nohash.conf
     etc/ssh/ssh_config.d/dsa.conf
     etc/ssh/sshd_config.d/root.conf
     etc/timezone
     etc/rsyslog.d/default.conf
     etc/rsyslog.d/central.conf
     home/youruser/.ssh/authorized_keys
     root/.ssh/authorized_keys
     root/.ssh/backup.id_rsa
     root/.ssh/backup.id_rsa.pub
     root/.ssh/known_hosts

     These will be unpacked onto the new system in the next step.

4. Start the VM, log in as root, and run the following commands on it (adjust as appropriate for your time zone etc.):

   tune2fs -L rootfs /dev/vda1
   ln -fs /usr/share/zoneinfo/Europe/Berlin /etc/localtime
   cd /
   tar -xvf fs.Excalibur.tgz
   rm -f fs.Excalibur.tgz
   apt-get install -y aptitude
   aptitude install -y less openntpd rsync vim
   aptitude purge -y nano vim-tiny
   echo 'syntax off' >>~/.vimrc
   [ -e /etc/default/su ] || echo ALWAYS_SET_PATH=yes >/etc/default/su
   cat /etc/default/su | grep -q ALWAYS_SET_PATH || echo ALWAYS_SET_PATH=yes >>/etc/default/su
   aptitude install -y parted acpi{d,-support-base} sendmail s-nail dnsutils
   echo 'RESUME=LABEL=swap' >/etc/initramfs-tools/conf.d/resume
   update-initramfs -k all -u

5. Shut down the server

You now have a VM server image which can be ddrescue'd over the top of a blank VM partition (3 Gbytes or bigger), and when booted, will be a usable VM in under 2 minutes using the NewInstantVM script..

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