A Simple installer for Nextcloud on Ubuntu Server

This work was heavily inspired/copied from https://github.com/nextcloud/vm so it inherits its GPL v3 licence.

It's a simplification over it on several points:

• it does not create a filesystem for the data directory or configure the disks: as there are about as many different configurations as there are users, we consider that directory already created and configured
• it does not create system users: for the same reasong. Instead, it relies on the default, existing system user to perform the sudos
• it does not configure the network, for the same reason
• it does not pre-install some Nextcloud apps: they can be installed simply when the server is up
• it does not pre-install Webmin: though a must-have, this script is focused on Nextcloud only
• it does not require a reboot, though it is recommended after upgrading all packages at the end of the installation
• it does not install a Let's Encrypt certificate (in the TODO list)
• it is idempotent: you should be able to run it several times and it should not mess up the system. If you can't, it should be considered as a bug.

Installation

1. Copy the vars.template to vars and edit the parameters:
   • NCBASE (default: /var/www) is where the Nextcloud archive will be extracted (i.e. $NCBASE/nexcloud usually)
   • NCDATA (default: none) is the Nextcloud data directory. Whether a simple folder, a simple disk, LLVM or RAID mount is up to the System Administrator. It is the only mandatory parameter.
   • NCUSER (default: ncadmin) is the Nextcloud Administrator. It is not a system account, but the login you should use when logging in the Nextcloud instance
   • NCPASS (default: auto-generated) is the Nextcloud Administrator password. *Be careful when using characters that could be interpreted by the shell (like ! or )! It is better to set a "simple" password and change it after installation.
   • PGDB_PASS (default: auto-generated) is the PostgreSQL administrator password
   • DBNAME (default: nextcloud) is the Nextcloud database name
   • PHPVER is the PHP version that should be installed. If not defined, the default PHP will be installed (apt install php) and its version will be read (PHP_VERSION constant)
   • NEXTCLOUDVER is the Nextcloud version that should be installed. If not defined, the latest available one will be used. Variable value will be grepped as grep "^$NEXTCLOUDVER" so it can be either "major" or "major.minor" or the fully-qualified version
2. As a sudoer, run sudo ./nextcloud_install.sh
   • A log file will be created detailing the main steps
3. Recommended: upgrade the whole system
   • apt update -q4 && apt dist-upgrade -y && apt autoremove --purge -y && apt autoclean

Bonus: installing Webmin

Because Webmin is such a cool tool, you can use the following snipet to install it (run as root):

if curl -fsSL http://www.webmin.com/jcameron-key.asc | sudo apt-key add - ; then
    echo "deb https://download.webmin.com/download/repository sarge contrib" > /etc/apt/sources.list.d/webmin.list
    apt update -q4
    apt install -qy webmin
fi