Compute

Instances

An instance is a KVM virtual machine in a project. It boots from an image onto a root volume in a storage class, gets a NIC in a subnet with security groups, and is configured at first boot by cloud-init.

stratumctl key-pairs import web --public-key-file ~/.ssh/id_ed25519.pub --project p-web
stratumctl instances create web-1 --image img-abc123 --instance-type m1.small \
  --subnet subnet-abc123 --security-group sg-abc123 --key-pair web \
  --public-ip --user-data-file cloud-init.yaml --project p-web
stratumctl instances get i-abc123 --project p-web

instances stop, start, reboot and terminate take the instance ID. Without an SSH path, stratumctl instances console-serial i-abc123 opens the serial console.

Instance types

Instance types are the sizes tenants launch: vCPUs, memory and a default root volume size. The install seeds m1.small to m1.xlarge.

stratumctl instance-types list
stratumctl instance-types create c1.large --vcpus 4 --memory-bytes 8589934592 \
  --default-root-volume-bytes 42949672960
stratumctl instance-types deprecate m1.small      # no new launches; running instances keep it

Capacity

How many more instances of each type fit, and which resource runs out first:

stratumctl nodes capacity
stratumctl nodes capacity --type m1.large

The numbers use the scheduler’s own arithmetic: (total − reserved) × overcommit − committed, for vCPU and memory.

Host reservation

Each node keeps part of its CPU and memory for the platform; instances get the rest. See Host reservation.