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then restart the 'avahi-daemon' if it is already running, by issuing "sudo service avahi-daemon restart". Note that even if the host-name is already defined in the Linux, make this 'host-name' explicit in 'Avahi' to match the data-store FQDN domain name will make sure it will still work even the host-name is changed by other services in the App. The 'use-ipv6=yes' is the default, and people have reported issues when 'Avahi' sometimes only gets the IPv6 address without wait for an IPv4 address and returns the reply, so this 'no' makes the reply have the IPv4 address always. The 'publish-workstation=yes' is to support the service of 'workstation'.
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At least one of the 'workstation' or 'http' or 'https' services has to be defined in the 'Avahi' for this local datastore feature to work.
Verify the App Side mDNS advertisement
An easy way to see if the App is running 'avahi-daemon' and advertising service/hostname correctly, One can issue "ps aux | grep 'avahi-daemon' " to see if it is running. Or one can issue "sudo systemctl status avahi-daemon" to see the 'avahi' status. Then install the 'avahi-browse' program by "sudo apt install avahi-utils". The 'avahi-browse -a" command output should display the hostname, service, etc info:
ubuntu@ubuntu:/etc/avahi$ avahi-browse -a | grep server
+ eth0 IPv4 ubuntu-4321-http-server [00:16:3e:00:01:03] Workstation local
+ lo IPv4 ubuntu-4321-http-server [00:00:00:00:00:00] Workstation local
Local DataStore Protocol Scheme
Since the EVE-OS 'downloader' module uses IP address in URL to fetch the images from the local Datastore, and also the datastore is internal to the device and under control by the user/enterprise, the protocol scheme should be HTTP. The downloaded images are verified by the datastore specified hash value for integrity of the image. In the case the HTTPS scheme needs to be used for the local datastore, the user needs to make sure the local datastore App interface IP address is statically assigned on the Network Instance configuration (so it will not change after reboot, etc.) and also the certificate's 'subjectAltName' needs to include this interface IP address, and the certificate chain is included in the local datastore configuration for EVE-OS to verify during the downloading operation.