How to cherry pick a package dependency when there are several providers

Question

I'm currently writing puppet config to automatically setup a number of system configurations, such as apache2 + php5 + mysql, nginx + php5 + mysql (in reality any http service a long with any addons and databases).

Many packages, such as wordpress, drupal, php5-fpm and more depends on libapache2-mod-php5 which in turn depends on apache2, apache2-common. In the non apache2 configurations (where nginx or similar services are used) this causes problems such as unnecessary installed packages, apache2 binds to the same port etc ..

Is there a way to specifically block packages, change priority of such or perhaps prefer other dependencies which may have lower prio? What approach can the problem be solved with?

Answer 1

You can prevent package installation adding a - (minus) sign after the package name, for example:

sudo apt-get install wordpress nginx-full php5 mariadb-client php5-mysqlnd apache2-
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package 'apache2' is not installed, so not removed
The following NEW packages will be installed:
  libdbd-mysql-perl libjs-cropper libjs-prototype libjs-scriptaculous
  libmariadbclient18 libphp-phpmailer libphp-snoopy mariadb-client
  mariadb-client-5.5 mariadb-client-core-5.5 mariadb-common nginx-common
  nginx-full php5 php5-cgi php5-gd php5-mysqlnd wordpress wordpress-l10n
  wordpress-theme-twentyfourteen wordpress-theme-twentytwelve
0 upgraded, 21 newly installed, 0 to remove and 24 not upgraded.

Of course, you need to select which package will replace it and not using any of the dependencies that also depends on apache like libapache2-mod-php5.

The above example was for wordpress, for drupal:

sudo apt-get install drupal7 nginx-full apache2-
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package 'apache2' is not installed, so not removed
The following extra packages will be installed:
  dbconfig-common libdbd-mysql-perl mysql-client mysql-client-5.5 mysql-server
  mysql-server-5.5 mysql-server-core-5.5 nginx-common php5 php5-cgi php5-gd
  php5-mysql wwwconfig-common
The following NEW packages will be installed:
  dbconfig-common drupal7 libdbd-mysql-perl mysql-client mysql-client-5.5
  mysql-server mysql-server-5.5 mysql-server-core-5.5 nginx-common nginx-full
  php5 php5-cgi php5-gd php5-mysql wwwconfig-common
0 upgraded, 15 newly installed, 0 to remove and 24 not upgraded.

You can modify it adding more packages if you like.