Functions I used to deploy a Debian server.

libDebian.sh

#!/bin/bash
#
# debian deployment script base, this script does nothing itself.
#
###########################################################
# System
###########################################################

function updateSystem {
    apt-get update
    apt-get -y install aptitude
    aptitude -y full-upgrade
}

function get_rdns_primary_ip {
    echo $(get_rdns $(system_primary_ip))
}

function addRepo {
    # add properties common
    aptitude -y install software-properties-common

    # MariaDB
    apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 0xcbcb082a1bb943db
    add-apt-repository 'deb http://ftp.osuosl.org/pub/mariadb/repo/10.0/debian wheezy main'    
    
    # Nginx
    curl http://nginx.org/keys/nginx_signing.key | apt-key add -
    echo "deb http://nginx.org/packages/mainline/debian/ wheezy nginx" | tee -a /etc/apt/sources.list
    echo "deb-src http://nginx.org/packages/mainline/debian/ wheezy nginx" | tee -a /etc/apt/sources.list

    # Varnish cache
    curl http://repo.varnish-cache.org/debian/GPG-key.txt | apt-key add -
    echo "deb http://repo.varnish-cache.org/ubuntu/ wheezy varnish-3.0" | tee -a /etc/apt/sources.list

    # Update the apt catalogue
    aptitude update
}

function configure_user {
    # $1 - username
    # $2 - password
    # $3 - sshkey
    #configure ssh/sudo 
    useradd -m -s /bin/bash $1 #add user account 
    groupadd sudo
    usermod -a -G sudo $1
    echo "$1:$2" | chpasswd #setpassword
    #add user to sudoers
    echo "$1 ALL=NOPASSWD: ALL" >> /etc/sudoers

    mkdir -p /home/$1/.ssh
    echo "$3" >> /home/$1/.ssh/authorized_keys
    chown -R $1:$1 /home/$1/.ssh
    chmod 700 /home/$1/.ssh
    chmod 600 /home/$1/.ssh/authorized_keys
}

function configure_systemSecurity {
    # NOPASSWD sudo by default
    # shut ports except tcp 22
    # lock out root
    sed -i 's/PermitRootLogin yes/PermitRootLogin no/g' /etc/ssh/sshd_config
    aptitude -y install fail2ban ufw
    passwd -l root
    printf "y\ny\ny\n" | ufw reset
    ufw default deny
    ufw allow ssh
    ufw logging on
    printf "y\ny\ny\n" | ufw enable
}


###########################################################
# mariadb-server
###########################################################

function install_mariadb {
    # $1 - the mysql root password
    if [ ! -n "$1" ]; then
        echo "install_mariadb() requires the root pass as its first argument"
        return 1;
    fi

    echo "mariadb-server-10.0 mariadb-server/root_password password $1" | debconf-set-selections
    echo "mariadb-server-10.0 mariadb-server/root_password_again password $1" | debconf-set-selections
    aptitude -y install mariadb-server
    echo "Sleeping while MySQL starts up for the first time..."
    sleep 5
}

function mysql_create_database {
    # $1 - the mysql root password
    # $2 - the db name to create

    if [ ! -n "$1" ]; then
        echo "mysql_create_database() requires the root pass as its first argument"
        return 1;
    fi
    if [ ! -n "$2" ]; then
        echo "mysql_create_database() requires the name of the database as the second argument"
        return 1;
    fi

    echo "CREATE DATABASE $2;" | mysql -u root -p$1
}

# mysql commands are compatible with mariadb.

function mysql_create_user {
    # $1 - the mysql root password
    # $2 - the user to create
    # $3 - their password

    if [ ! -n "$1" ]; then
        echo "mysql_create_user() requires the root pass as its first argument"
        return 1;
    fi
    if [ ! -n "$2" ]; then
        echo "mysql_create_user() requires username as the second argument"
        return 1;
    fi
    if [ ! -n "$3" ]; then
        echo "mysql_create_user() requires a password as the third argument"
        return 1;
    fi

    echo "CREATE USER '$2'@'localhost' IDENTIFIED BY '$3';" | mysql -u root -p$1
}

function mysql_grant_user {
    # $1 - the mysql root password
    # $2 - the user to bestow privileges 
    # $3 - the database

    if [ ! -n "$1" ]; then
        echo "mysql_create_user() requires the root pass as its first argument"
        return 1;
    fi
    if [ ! -n "$2" ]; then
        echo "mysql_create_user() requires username as the second argument"
        return 1;
    fi
    if [ ! -n "$3" ]; then
        echo "mysql_create_user() requires a database as the third argument"
        return 1;
    fi

    echo "GRANT ALL PRIVILEGES ON $3.* TO '$2'@'localhost';" | mysql -u root -p$1
    echo "FLUSH PRIVILEGES;" | mysql -u root -p$1

}


###########################################################
# Other niceties!
###########################################################

function goodstuff {
    # Installs the REAL vim, wget, less, and enables color root prompt and the "ll" list long alias

    aptitude -y install wget vim less axel tmux subversion git zsh mercurial
    sed -i -e "s/^#alias ll='ls -l'/alias ll='ls -al'/" /root/.bashrc # enable ll list long alias <3
}


###########################################################
# utility functions
###########################################################

function restartServices {
    # restarts services that have a file in /tmp/needs-restart/

    for service in $(ls /tmp/restart-* | cut -d- -f2-10); do
        /etc/init.d/$service restart
        rm -f /tmp/restart-$service
    done
}

function randomString {
    if [ ! -n "$1" ];
        then LEN=20
        else LEN="$1"
    fi

    echo $(</dev/urandom tr -dc A-Za-z0-9 | head -c $LEN) # generate a random string
}