Availability zone

An availability zone (AZ) is a logical grouping of Multipass instances, modelled after the availability zones of public cloud providers. Zones let you spread instances out and simulate the loss of part of your “infrastructure”, without affecting instances in other zones.

Every instance belongs to exactly one zone, chosen at launch time and visible as the Zone field in multipass info and multipass list output.

Default zones

Out of the box, Multipass creates three zones: zone1, zone2 and zone3. Each zone reserves its own subnet, so instances in different zones never share the same private network. Use multipass zones to see the current zones, their availability, and the subnet assigned to each one.

Choosing a zone at launch

By default, multipass launch assigns the new instance to a zone automatically: Multipass cycles through the available zones, so consecutive launches without an explicit zone tend to land in different zones. Use the --zone option to pin the instance to a specific zone instead:

multipass launch --zone zone2

Simulating an outage

multipass disable-zones makes one or more zones unavailable, simulating a loss of availability on a cloud provider:

  • Any running instances in the affected zones are forcefully switched off, and their state is reported as Unavailable (see Instance states).

  • Multipass refuses to launch new instances into a disabled zone, and refuses to start or otherwise interact with the instances already there, until the zone is re-enabled.

multipass enable-zones reverses this: the zone becomes available again, and any instances that were running when the zone was disabled are started back up.

This makes it possible to test how a multi-instance deployment behaves when part of it becomes unreachable, without actually deleting or reconfiguring anything.