Module Init Notes

What should happen when someone installs an apache module? Certainly copy a .so file to the right place but what else. Should we

enable the module? Debian-based OS have a concept of "modules available" vs. "modules enabled"
restart apache? and if so, how? If installed in a docker image, then this step is unlikely to happen

What should happen when the module is un-installed?

CentOS Family

Unable to find anything on RedHat or CentOS packaging
Fedora Draft guidelines
Fedora guidelines appears worthless
CentOS 5 is apache 2.2, and CentOS 7 is apache 2.4,, but
CentOS 6 has both
Appears that CentOS Family, installs module, enables module but does not do anything with the apache server.
On uninstall, the .conf file that loads the module is removed and that's the end of that.

# rpm --query --fileprovide  mod_passenger
/etc/httpd/conf.d/passenger.conf
/etc/httpd/conf.modules.d/passenger.conf
/usr/lib64/httpd/modules/mod_passenger.so
/usr/share/doc/mod_passenger-4.0.53
/usr/share/doc/mod_passenger-4.0.53/Users guide Apache.txt

# cat /etc/httpd/conf.modules.d/passenger.conf
LoadModule passenger_module modules/mod_passenger.so

# cat /etc/httpd/conf.d/passenger.conf
<IfModule mod_passenger.c>
   PassengerRoot /usr/share/passenger//phusion_passenger/locations.ini
   PassengerRuby /usr/bin/ruby
</IfModule>

# Deploying a Ruby on Rails application: an example

# Suppose you have a Rails application in /somewhere. Add a virtual host to
# your Apache configuration file and set its DocumentRoot to /somewhere/public:
#
#    <VirtualHost *:80>
#       ServerName www.yourhost.com
#       Be sure to point to 'public'!
#       DocumentRoot /somewhere/public
#       <Directory /somewhere/public>
#          Relax Apache security settings
#          AllowOverride all
#          MultiViews must be turned off
#          Options -MultiViews
#       </Directory>
#    </VirtualHost>

Debian Family

https://wiki.debian.org/Apache/PackagingFor24
https://wiki.debian.org/Apache/PackagingModules
Use passenger as test case
apt-get update; apt-get install libapache2-mod-passenger
pre/post install files are in /var/lib/dpkg/info/libapache2-mod-passenger*
TLDR; pre-install enables module and restarts server while prerm disables module.

conf file layout:

# cat /var/lib/dpkg/info/libapache2-mod-passenger.conffiles
/etc/apache2/mods-available/passenger.conf
/etc/apache2/mods-available/passenger.load

# cat /etc/apache2/mods-available/passenger.load
LoadModule passenger_module /usr/lib/apache2/modules/mod_passenger.so

# cat /etc/apache2/mods-available/passenger.conf
<IfModule mod_passenger.c>
  PassengerRoot /usr/lib/ruby/vendor_ruby/phusion_passenger/locations.ini
  PassengerDefaultRuby /usr/bin/ruby
</IfModule>

Debian 10 -- buster

2.4.38 -- https://packages.debian.org/buster/apache2
see ubuntu 14.04

Debian 9 -- stretch

2.4.25 -- https://packages.debian.org/stretch/apache2
see ubuntu 14.04

Debian 8 -- jessie

2.4.10 -- https://packages.debian.org/jessie/apache2
see ubuntu 14.04

Debian 7 -- wheezy

2.2.22 -- https://packages.debian.org/wheezy/apache2
see ubuntu 12.04

Ubuntu 18.04 -- bionic

2.4.29 -- https://packages.ubuntu.com/bionic/apache2
scripts are identical to ubuntu 14.04

Ubuntu 16.04 -- xenial

2.4.18 -- https://packages.ubuntu.com/xenial/apache2
scripts are identical to ubuntu 14.04

Ubuntu 14.04 -- trusty

2.4.7 -- https://packages.ubuntu.com/trusty/apache2
has 3 scripts, preinst, prerm, postrm

Ubuntu 12.04 --

2.2.22
Same as Debian 7
install scripts are in /var/lib/dpkg/info
on post-install: enable module, and reload server
on pre-remove: disable module, do not reload server

ubuntu 12.04 mod-passenger sample

Taken from libapache2-mod-passenger.postinst

#!/bin/sh

set -e

if [ "$1" != "configure" ]; then
  exit 0
fi

reload_apache()
{
  if apache2ctl configtest 2>/dev/null; then
    invoke-rc.d apache2 force-reload || true
  else
    echo "Your apache2 configuration is broken, so we're not restarting it for you."
  fi
}

if [ -n "$2" ]; then
# we're upgrading. test if we're enabled, and if so, restart to reload the module.
  if [ -e /etc/apache2/mods-enabled/passenger.load ]; then
    reload_apache
  fi
    exit 0
fi

if [ -e /etc/apache2/apache2.conf ]; then
# Enable the module, but hide a2enmod's misleading message about apachectl
# and force-reload the thing ourselves.
        a2enmod passenger >/dev/null || true
  reload_apache
fi
exit 0

Taken from libapache2-mod-passenger.prerm

#!/bin/sh

set -e

if [ "$1" != "remove" -a "$1" != "purge" ]; then
  exit 0
fi;

if [ -e /etc/apache2/apache2.conf ]; then
  a2dismod passenger || true
fi

exit 0

ubuntu 12.04 mod-uwsgi sample

Taken from libapache2-mod-uwsgi.postinst

#!/bin/sh
# postinst script for libapache2-mod-uwsgi
#
# see: dh_installdeb(1)

set -e

apache_force_reload() {
  if apache2ctl configtest 2>/dev/null; then
    invoke-rc.d apache2 force-reload || true
  else
    echo "Your apache2 configuration is broken, please fix it and restart apache2 manually."
  fi
}

# summary of how this script can be called:
#        * <postinst> `configure' <most-recently-configured-version>
#        * <old-postinst> `abort-upgrade' <new version>
#        * <conflictor's-postinst> `abort-remove' `in-favour' <package>
#          <new-version>
#        * <postinst> `abort-remove'
#        * <deconfigured's-postinst> `abort-deconfigure' `in-favour'
#          <failed-install-package> <version> `removing'
#          <conflicting-package> <version>
# for details, see http://www.debian.org/doc/debian-policy/ or
# the debian-policy package

case "$1" in
    configure)
      if [ -z "$2" ]; then # installing package
        if [ -e /etc/apache2/apache2.conf ]; then
          a2enmod uwsgi >/dev/null || true
          apache_force_reload
        fi
      else # upgrading package
        if [ -e /etc/apache2/mods-enabled/uwsgi.load ]; then
          apache_force_reload
        fi
      fi
    ;;

    abort-upgrade|abort-remove|abort-deconfigure)
    ;;

    *)
        echo "postinst called with unknown argument \`$1'" >&2
        exit 1
    ;;
esac

# dh_installdeb will replace this with shell code automatically
# generated by other debhelper scripts.

Ubuntu 14.04

postinst

#!/bin/sh
# postinst script for libapache2-mod-uwsgi
#
# see: dh_installdeb(1)

set -e

# summary of how this script can be called:
#        * <prerm> `remove'
#        * <old-prerm> `upgrade' <new-version>
#        * <new-prerm> `failed-upgrade' <old-version>
#        * <conflictor's-prerm> `remove' `in-favour' <package> <new-version>
#        * <deconfigured's-prerm> `deconfigure' `in-favour'
#          <package-being-installed> <version> `removing'
#          <conflicting-package> <version>
# for details, see http://www.debian.org/doc/debian-policy/ or
# the debian-policy package

if [ "$1" = "configure" ] ; then
    if [ -e /usr/share/apache2/apache2-maintscript-helper ] ; then
        . /usr/share/apache2/apache2-maintscript-helper
        apache2_invoke enmod uwsgi  || exit 1
    fi
fi

# dh_installdeb will replace this with shell code automatically
# generated by other debhelper scripts.

exit 0

#!/bin/sh
# prerm script for libapache2-mod-uwsgi
#
# see: dh_installdeb(1)

set -e

# summary of how this script can be called:
#        * <prerm> `remove'
#        * <old-prerm> `upgrade' <new-version>
#        * <new-prerm> `failed-upgrade' <old-version>
#        * <conflictor's-prerm> `remove' `in-favour' <package> <new-version>
#        * <deconfigured's-prerm> `deconfigure' `in-favour'
#          <package-being-installed> <version> `removing'
#          <conflicting-package> <version>
# for details, see http://www.debian.org/doc/debian-policy/ or
# the debian-policy package

if [ "$1" = "purge" ] ; then
    if [ -e /usr/share/apache2/apache2-maintscript-helper ] ; then
        . /usr/share/apache2/apache2-maintscript-helper
        apache2_invoke dismod uwsgi  || exit 1
    fi
fi

# dh_installdeb will replace this with shell code automatically
# generated by other debhelper scripts.

exit 0

ubuntu 14.04 passenger

3 sections

postinst

#!/bin/sh
set -e
# Automatically added by dh_apache2
if true; then
    if [ -e /usr/share/apache2/apache2-maintscript-helper ] ; then
        . /usr/share/apache2/apache2-maintscript-helper
        for conf in passenger  ; do
            apache2_invoke enmod $conf  || exit $?
        done
    fi
fi
# End automatically added section

prerm

#!/bin/sh
set -e
# Automatically added by dh_apache2
if [ "$1" = "remove" ] || [ "$1" = "deconfigure" ] ; then
    if true; then
        if [ -e /usr/share/apache2/apache2-maintscript-helper ] ; then
            . /usr/share/apache2/apache2-maintscript-helper

            for conf in passenger  ; do
                apache2_invoke dismod $conf  || exit $?
            done
        fi
    fi
fi
# End automatically added section

postrm

#!/bin/sh
set -e
# Automatically added by dh_apache2
if [ "$1" = "purge" ] ; then
    if true; then
        if [ -e /usr/share/apache2/apache2-maintscript-helper ] ; then
            . /usr/share/apache2/apache2-maintscript-helper

            for conf in passenger  ; do
                apache2_invoke dismod $conf  || exit $?
            done
        fi
    fi
fi
# End automatically added section