Use device UUID in hostname for unique mDNS identification

[mihai-chiorean]

Description

Currently, the hostname is generated using device serial or MAC address. We should use the already-generated device UUID (from edgeos-identity) to create a unique, persistent hostname that's broadcasted via mDNS.

Current Behavior

• Hostname: edgeos-${serial_last_8_chars}
• UUID is generated separately in /etc/edgeos/device-uuid
• Two separate identity systems

Desired Behavior

• Generate hostname using the device UUID
• Format: edgeos-${uuid_last_8_chars} or similar
• Ensure mDNS broadcasts the correct hostname
• Single source of truth for device identity

Implementation Requirements

1. Modify hostname generation flow:

   • edgeos-identity service generates UUID first
   • Hostname derived from UUID (not serial/MAC)
   • Both happen before network services start

2. Update generate-hostname.sh:

   # Read UUID from /etc/edgeos/device-uuid
   if [ -f /etc/edgeos/device-uuid ]; then
       UUID=$(cat /etc/edgeos/device-uuid)
       SHORT_ID=${UUID: -8}
       HOSTNAME="edgeos-${SHORT_ID}"
   fi

3. Service ordering:

   • edgeos-identity.service (generates UUID)
   • edgeos-hostname.service (sets hostname from UUID)
   • avahi-daemon.service (broadcasts hostname)

Benefits

• Single identity source (UUID)
• Consistent device identification across all services
• UUID already used in mDNS TXT records
• Simpler troubleshooting with matching identifiers

Acceptance Criteria

• Hostname generated from device UUID
• UUID generation happens before hostname setting
• mDNS broadcasts correct UUID-based hostname
• Hostname persists across reboots
• Both hostname and UUID use same identifier
• Backward compatibility considered