NTACurrent en:Upgrading Debian 10 to Debian 11

Overview

This page provides a step-by-step guide for the distribution upgrade from Debian 10 to Debian 11, tailored to the minimal set of packages that are required for Cryptshare for Mail Gateway. To see the full official guide visit https://www.debian.org/releases/bullseye/amd64/release-notes/ch-upgrading.en.html.

Preparation

Create a backup/snapshot of the system before installing, to restore the initial state easily.
Inform your users about the downtime of the system, which will be (depending on the speed of the internet connection) around 1-2 hours. During the upgrade, messages will not be delivered reliably.

Upgrade steps

Become root:
```
sudo su
```

Remove inofficial packages (config files remain)

apt remove ansible
apt remove postfix
apt autoremove

Clean up /etc/apt/sources.list, replace contents with:

deb http://deb.debian.org/debian/ buster main
deb-src http://deb.debian.org/debian/ buster main

deb http://security.debian.org/debian-security buster/updates main
deb-src http://security.debian.org/debian-security buster/updates main

deb http://deb.debian.org/debian/ buster-updates main
deb-src http://deb.debian.org/debian/ buster-updates main

Update to latest Buster packages:

apt update
apt upgrade
apt full-upgrade
apt autoremove
reboot

Become root again:
```
sudo su
```

Replace contents of /etc/apt/sources.list with:

deb http://deb.debian.org/debian bullseye main contrib non-free
deb http://deb.debian.org/debian bullseye-updates main contrib non-free
deb http://security.debian.org/debian-security bullseye-security main contrib non-free

Perform the upgrade:
```
apt clean
apt update
apt full-upgrade
```
Shortly after loading the information for all packages, release notes are displayed. Confirm these with the Q key.

Answer questions during package upgrades.

Questions like this:

Configuration file '/etc/powerdns/recursor.conf'
 ==> Modified (by you or by a script) since installation.
 ==> Package distributor has shipped an updated version.
   What would you like to do about it ? Your options are:
    Y or I  : install the package maintainer's version
    N or O  : keep your currently-installed version
      D     : show the differences between the versions
      Z     : start a shell to examine the situation
 The default action is to keep your current version.
*** recursor.conf (Y/I/N/O/D/Z) [default=N] ?

For /etc/resolvconf/resolv.conf.d/head: N
For /etc/opendkim.conf: N
For /etc/opendmarc.conf: N
For /etc/powerdns/recursor.conf: N

Question about dbconfig-common for OpenDMARC: No
Question about libc6 upgrade: Yes
Question about libc6 automated restarts: Yes

Reboot:
```
reboot
```
Become root again:
```
sudo su
```

Install Postfix and SPF deamon again:

apt install postfix
# -> Answer question with "No configuration"

apt install postfix-pgsql
apt install postfix-policyd-spf-python

Update PostgreSQL

Stop services

systemctl stop cmg-filter
systemctl stop postgresql

Start upgrade

su postgres
cd /tmp
/usr/lib/postgresql/13/bin/pg_upgrade --old-datadir=/var/lib/postgresql/11/main --new-datadir=/var/lib/postgresql/13/main --old-bindir=/usr/lib/postgresql/11/bin --new-bindir=/usr/lib/postgresql/13/bin --old-options '-c config_file=/etc/postgresql/11/main/postgresql.conf' --new-options '-c config_file=/etc/postgresql/13/main/postgresql.conf'
exit

Remove old installation

apt purge postgresql-11
# -> Answer question with yes, remove configuration files

apt purge postgresql-client-11
/tmp/delete_old_cluster.sh

Edit /etc/postgresql/13/main/postgresql.conf, change port back to default
```
...
port = 5432
...
```
Restart PostgreSQL service
```
systemctl restart postgresql
```

Reboot one last time:
```
reboot
```