Couple of changes:
- move home to /var/lib/ddclient so we can enable ProtectSystem=full
- do not stick binary into systemPackages as it will only run as a daemon
- run as dedicated user/group
- document why we cannot run as type=forking (output is swallowed)
- secure things by running with ProtectSystem and PrivateTmp
- .pid file goes into /run/ddclient
- let nix create the home directory instead of handling it manually
- make the interval configurable
This avoids the following warning:
Apr 19 10:53:48 xen systemd[1]: [/nix/store/...-unit-ddclient.service/ddclient.service:19] Unknown lvalue 'type' in section 'Service'
As `Type=simple` is the default in systemd, the assignment to the
service type can be simply dropped.
* rewrite to systemd.services
* disable forking to give systemd better control
* verifiably run as ddclient user
* expose ssl option
* unset default value for dyndns server
* rename option "web" to "use" to be consistent with ddclient docs
* add descriptions
* add types to options
* clean up formatting
