VM interfaces
A VM interface is a network attachment on a VM — the binding between the VM and one of its network ports. Most VMs are fine with the default interface created at launch; you only manage interfaces directly when you need to attach a VM to multiple networks (e.g. dual-homed services, blue/green network swings).
Attaching an interface is hot — the VM doesn't reboot. The kernel sees the new NIC immediately; you may need to bring it up (ip link set <name> up) and configure addressing manually unless the image's cloud-init handles it.
Detaching is also hot. Sockets bound to the detached interface drop; sockets on other interfaces are unaffected.
What's next
- Virtual machines — the parent resource these interfaces belong to.
- Networks and Subnets — what an interface attaches to.
- Floating IPs — the public-IP layer on top of an interface.