This commit adds an *after* ordering dependency on the network device
unit to the *wait-global-address@.service* template unit. Without this
dependency, the service will wait forever for a global address if the
device does not exist. With the dependency, though, if the device does
not appear within the default timeout, the wait service will never
start, causing all dependent services to fail, but allowing the boot
process to continue.
The *dch-storage-net* role configures a machine to connect the storage
network and mount shared folders from the storage appliance.
The `wait-global-address.sh` script and corresponding
*wait-global-address@.service* systemd unit template are necessary to
ensure that the storage network is actually available before attempting
to mount the shared volumes. This is particularly important at boot,
since `dhcpcd` does not implement any kind of signaling that can be used
by *network-online.target*, so the network is considered "online" as
soon as the `dhcpcd` process has started. This typically results in
"network unreachable" errors.
Dustin