checkips vdsm hook
=====================
This hook check connectivity from host to given addresses

This hook is useful in cases where you need to check connectivity from host to
specific VLAN, you just need to add custom property checkipv4 or checkipv6,
depend on what type of IP do you want to check, to network.

Syntax:
    checkipv4=IPV4 or FQDN
    checkipv6=IPV6 or FQDN

Where:
    IPV4 is ip address in IPV4 format
    IPV6 is ip address in IPV6 format

Example:
    checkipv4=127.0.0.1
    checkipv6=::1

Installation:
    - Use the engine-config to append the proper custom property:
        $ sudo engine-config -s UserDefinedNetworkCustomProperties='checkipv4=^[0-9\.a-fA-F]+$;checkipv6=^[0-9\.a-fA-F\:]+$'
    - Verify that the checkipv4 and checkipv6 custom properties was properly added:
        $ sudo engine-config -g UserDefinedNetworkCustomProperties
    - Restart ovirt-engine service to apply changes
        $ sudo service ovirt-engine restart
    - The hook should be installed on all hosts,
      and its accompanying service should be enabled and started
        systemctl vdsm-checkips enable
        systemctl vdsm-checkips start

Usage:
    In the host setup network configuration window, choose edit assigned
    logical network, select custom property checkipv4 or checkipv6 and
    enter VLAN IP or FQDN that you want to check for
    connectivity(examples 8.8.8.8,2001:4860:4860::8888). So if you defined
    checkipv4 and checkipv6 custom properties and if the host fails to ping
    both IP's, it will drop the network's state to down.
    If the network is defined as "required",
    the host would become non-operational.