Debian Stretch was released last month, so it is time to upgrade my laptop. I’m an i3 window manager user. Previously my procedure was to backup /home, reinstall using the network installer (I don’t like apt-get dist-upgrade, I like to start clean) and tick the “Debian Desktop Environment … GNOME” checkbox and after the installer was done, install i3 and the rest of my tools.

While I use some of the tools from Gnome, like gnome-terminal, network manager, nautilus and Eye of Gnome, I do not really need the complete Gnome desktop environment and 100s of software packages that come with it. This time I want a basic system with only the tools I need. And I want to upgrade in-place without losing my Debian jessie install.

Some notes about the installation:

• It’s a Lenovo Thinkpad T450s
• I currently have 2 partitions: 1 for /boot and the other is encrypted with luks
• The encrypted partition contains 3 logical volumes for /, /home and swap
• A 4th lv (logical volume) will be created for the new root partition for Debian stretch
• The new lv will be BTRFS formatted and I’ll use a BTRFS subvolume to be able to create snapshots of it
• The minimal required software will be installed to run the i3 window manager, including some tools I regularly use.

Let’s prepare the root volume:

VG=bento # my lvm2 volume group is called bento
LV=stretch # the new lv will be called stretch
LABEL=stretch # label for btrfs

lvcreate -L10G -n $LV $VG
mkfs.btrfs -L $LABEL /dev/$VG/$LV

mkdir /mnt/$LV
mount /dev/$VG/$LV /mnt/$LV
cd /mnt/$LV
# create the root subvolume
btrfs subvolume create @
cd -
umount /mnt/$LV
# mount the subvolume instead
mount -o subvol=/@ /dev/$VG/$LV /mnt/$LV

The boot partition (/boot) will be reused/shared between the current Debian jessie install and the new stretch install. Because I still use Debian jessie daily for my work, I still want to be able to boot jessie as a fallback. To see what happens to /boot/grub and especially /boot/grub/grub.cfg I will make a git repository in /boot/grub.

cd /boot/grub
git init
git add -A .
git commit -am 'grub at the time jessie was still installed'

Let’s start with the install:

/usr/sbin/debootstrap --include udev,openssh-server,linux-image-amd64 stretch /mnt/$LV http://deb.debian.org/debian/

# the new system needs to know about the encrypted partition, so copy crypttab
cp /etc/crypttab /mnt/$LV/etc/crypttab

# configure /mnt/$LV/etc/fstab
# example contents (replace $UUID with the uuid of /boot, replace $LABEL with the btrfs label)
UUID=$UUID /boot ext4 defaults 0 2
LABEL=$LABEL / btrfs subvol=/@,defaults,noatime 0 0
LABEL=$LABEL /btrfs-root btrfs subvol=/,defaults,noatime 0 0
# optionally add the existing mountpoint for /home

# The root of the BTRFS filesystem is mounted at `/btrfs-root`. From here we can manage the subvolumes and snapshots
mkdir /mnt/$LV/btrfs-root

# chroot into the new system
mount -o bind /boot /mnt/$LV/boot/
mount -o bind /dev /mnt/$LV/dev/
mount -t proc proc /mnt/$LV/proc
mount -t sysfs sys /mnt/$LV/sys
chroot /mnt/$LV

# set a root password
passwd
# create a normal user account
adduser pommi

# we do not want recommended packages to be installed automatically
echo 'APT::Install-Recommends "false";' > /etc/apt/apt.conf.d/00InstallRecommends

# stable and security updates
cat > /etc/apt/sources.list <<EOT
deb http://deb.debian.org/debian stretch main contrib non-free
deb http://deb.debian.org/debian stretch-updates main contrib non-free
deb http://security.debian.org/ stretch/updates main contrib non-free
EOT
apt-get update
apt-get upgrade

# install some basics
apt-get install cryptsetup lvm2 locales busybox less grub-pc git vim-nox initramfs-tools btrfs-progs

# set the default locale (to for example en_US.UTF-8)
dpkg-reconfigure locales

# set the timezone
dpkg-reconfigure tzdata

The basics are done. Now install the Desktop Environment. To graphically login after booting I chose lightdm, which is a lightweight display manager. Gnome comes with gdm (Gnome Display Manager), but that installs ~87 another software packages I don’t want.

# suckless-tools for dmenu, x11-xserver-utils for xrandr
apt-get install lightdm i3 i3status suckless-tools xserver-xorg x11-xserver-utils

# networking, including wifi, gnome-keyring to store wifi passwords
apt-get install network-manager-gnome firmware-iwlwifi firmware-linux gnome-keyring

# and a terminal and a browser
apt-get install gnome-terminal firefox-esr

The system is now ready. Let’s check the changes in /boot/grub before we reboot.

cd /boot/grub
git status
git diff
# commit the changes
git add -A .
git commit -m 'after installing stretch'

In my case I had (at least) 2 kernels present in /boot. An active one for jessie (/vmlinuz-3.16.0-4-amd64) and a new one for stretch (/vmlinuz-4.9.0-3-amd64). When update-grub was executed from stretch just now, it changed all the grub menu items to boot into the new stretch system (every “linux” line now contains: root=/dev/mapper/$VG-$LV). To be able to still boot to jessie, I revert the changes for the “linux” lines that are supposed to boot the jessie system (/vmlinuz-3.16.0-4-amd64 kernels).

For example, change this:

linux /vmlinuz-3.16.0-4-amd64 root=/dev/mapper/bento-stretch ro quiet

back to (“root” is my current root lv):

linux /vmlinuz-3.16.0-4-amd64 root=/dev/mapper/bento-root ro quiet

And commit the result:

git add grub.cfg
git commit -m 'boot jessie with the old kernel'

Time to reboot to stretch

# exit the chroot
exit
umount /mnt/$LV/sys
umount /mnt/$LV/proc
umount /mnt/$LV/dev/
umount /mnt/$LV/boot/
umount /mnt/$LV
reboot

Lightdm will start and show you a login screen. Login using the normal user you just created an i3 will start.

Additional software and configuration

Lock screen (Ctrl+Alt+l and after 5 minutes):

apt-get install i3lock xautolock
echo 'exec xautolock -time 5 -locker i3lock' >> .config/i3/config
echo 'bindsym Control+$alt+l exec xautolock -locknow' >> .config/i3/config

Start Network Manager Applet on startup

echo 'exec --no-startup-id nm-applet' >> .config/i3/config

Open urls from gnome-terminal in firefox:

apt-get install xdg-utils
xdg-settings get default-web-browser
xdg-settings set default-web-browser firefox-esr.desktop