My system (Ubuntu 18.04.1) is a VPS running on KVM. The network with some additional IPs is configured with Netplan.
The Apache server is running on an additional IP. If the VPS reboots, the apache didn’t start because, it couldn’t be bind on an aditional IP. A log entry like the following can be found:
apachectl: (99)Cannot assign requested address: AH00072: make_sock: could not bind to address [xxxxxxxx]:80
But if you restart Apache after the reboot, it runs as expected!
Strange, isn’t it?
Ok, I couldn’t find the exact reason of this reason. But I think, there is a strange timing issue on reboot. The network isn’t completely up before Apache is starting.
To solve the problem, just edited the section ‘Unit’ in the file /lib/systemd/system/apache2.service and replace
After=network.target remote-fs.target nss-lookup.target
Requires=network-online.target After=network-online.target remote-fs.target nss-lookup.target
More information about the network-target can be found her: https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget/