Intro to debconf
tl;dr
debcnofis a configuration management tool- all the questions you get during installing
.debpackages are stored indebconf - You can preload answers to those questions to get non-interactive/slient installations
- needs
sudo
sudo apt install debconf-utils
# get configurable values for a package
sudo debconf-get-selections | grep mysql
# set values
echo "set mysql-server/root_password YOURPASSWORD" | debconf-communicate
# sudo debconf-set-selections <<< "mysql-server mysql-server/root_password password YOURPASSWORD"
# echo 'mysql-server mysql-server/root_password password YOURPASSWORD' | debconf-set-selections
# show the list of debconf values configured for a package
debconf-show phpmyadmin
debconf is a configuration management tool for Debain. It let’s you pre-load configurations, meaning you set configuration options before instaling a package. The major benefit of this is during scripting, you can pre-configure the values via debconf-set-selections and avoid entering values in the prompt, getting a non-interactive install.
Debconf keeps all answers to questions packages can ask during installation, both the ones you gave yourself and the implied or low-priority ones chosen by the packager.
When using .deb-packages you’re used to getting asked about licenses, values, locations, downloads etc. All these are stored in debconf. You can preload those answers before so they won’t get asked during installation (a silent, scriptable, install) or to “steer” the package into your desired config-direction.
The only issue is figuring out what the selections mean. For example, if you have gone through the install process of PHPMyAdmin a few times, you might be able to figure out what the five different password selections correspond to.
# install debconf-utils to get `debconf-get-selections`
sudo apt install debconf-utils
Find out what values can be configured
sudo debconf-get-selections | grep mysql
phpmyadmin phpmyadmin/mysql/app-pass password
mysql-server-5.7 mysql-server/root_password_again password
dbconfig-common dbconfig-common/mysql/admin-pass password
dbconfig-common dbconfig-common/mysql/app-pass password
phpmyadmin phpmyadmin/mysql/admin-pass password
mysql-server-5.7 mysql-server/root_password password
mysql-server-5.7 mysql-server-5.7/really_downgrade boolean false
phpmyadmin phpmyadmin/mysql/method select Unix socket
dbconfig-common dbconfig-common/mysql/admin-user string
dbconfig-common dbconfig-common/mysql/method select Unix socket
phpmyadmin phpmyadmin/database-type select mysql
mysql-server-5.7 mysql-server/password_mismatch error
mysql-server-5.7 mysql-server/no_upgrade_when_using_ndb error
phpmyadmin phpmyadmin/mysql/admin-user string debian-sys-maint
mysql-server-5.7 mysql-server-5.7/nis_warning note
mysql-server-5.7 mysql-server-5.7/postrm_remove_databases boolean false
mysql-server-5.7 mysql-server-5.7/start_on_boot boolean true
Set/Confgiure values
sudo debconf-set-selections <<< "mysql-server mysql-server/root_password password YOURPASSWORD"
# OR
echo 'mysql-server mysql-server/root_password password YOURPASSWORD' | debconf-set-selections
# OR
echo "set mysql-server/root_password YOURPASSWORD" | debconf-communicate
Get details about an already configured package
Show the list of debconf values that a package has stored
# debconf-show packagename
debconf-show phpmyadmin
phpmyadmin/password-confirm: (password omitted)
phpmyadmin/app-password-confirm: (password omitted)
phpmyadmin/setup-password: (password omitted)
phpmyadmin/mysql/app-pass: (password omitted)
phpmyadmin/mysql/admin-pass: (password omitted)
phpmyadmin/remote/host: localhost
phpmyadmin/upgrade-backup: true
phpmyadmin/dbconfig-upgrade: true
phpmyadmin/dbconfig-reinstall: false
phpmyadmin/db/dbname: phpmyadmin
phpmyadmin/passwords-do-not-match:
* phpmyadmin/mysql/admin-user: debian-sys-maint
phpmyadmin/internal/reconfiguring: false
phpmyadmin/database-type: mysql
phpmyadmin/setup-username: admin
phpmyadmin/missing-db-package-error: abort
phpmyadmin/remove-error: abort
phpmyadmin/upgrade-error: abort
phpmyadmin/install-error: abort
phpmyadmin/dbconfig-remove: true
phpmyadmin/remote/port:
phpmyadmin/purge: false
* phpmyadmin/reconfigure-webserver: apache2
phpmyadmin/db/app-user: phpmyadmin
phpmyadmin/internal/skip-preseed: false
phpmyadmin/mysql/method: Unix socket
* phpmyadmin/dbconfig-install: true
phpmyadmin/remote/newhost:
to query the current value of an option in the debconf database
echo "get packagename/pgsql/app-pass" | debconf-communicate
and to change that value
echo "set packagename/pgsql/app-pass password1" | debconf-communicate
Getting and setting values with a file
debconf-get-selections | grep application > file
# and edit the file, then use
debconf-set-selections < file
# to load the changed settings.
Backup debconf configurations
debconf-get-selections > debconf-selections-backup-`date +%Y%m%d`