host power

Some VM hosts are not always on. Examples are an on-demand cloud instance that stops when idle, a lab machine behind a smart plug, and a workstation with Wake-on-LAN. The host-power hook lets the web UI show these machines and power them on and off. Corral core contains no provider code. Any installed plugin that declares the host-power capability provides it (ADR-0007).

Contract (corral.plugin/v1)

The plugin lists host-power in its --corral-plugin-metadata capabilities and provides these commands:

Command	Output
corral-<name> host-power list	JSON array of sdk.Host on stdout
corral-<name> host-power start <id>	exit 0 once the provider accepted the request
corral-<name> host-power stop <id>	exit 0 once the provider accepted the request

[{"id": "eu-north-1/i-0abc", "name": "KubeVirt (AWS)", "node": "ip-10-20-1-12",
  "state": "stopped", "actions": ["start"], "detail": "m7i.2xlarge · eu-north-1"}]

state is one of running, stopped, starting, stopping or unknown. actions lists the actions that a user can request now. node ties the host to a Kubernetes node, so the UI can show which VMs it carries.

Web API

• GET /api/hostpower returns the hosts from every capable plugin. If a plugin fails, the response reports it under errors and still shows the others.
• POST /api/hostpower/{plugin}/{start|stop}?id=<id> is admin-gated, like every mutation (CORRAL_ADMINS).

Each plugin call times out after 30 s.

First-party provider: aws-power

corral-aws-power manages the EC2 instances that have the tag corral:host-power (the value is the display name), optionally with corral:node=<k8s node>. Configure it with CORRAL_AWS_POWER_REGIONS (or AWS_REGION) and standard AWS credentials. Scope the credentials to ec2:DescribeInstances plus ec2:StartInstances/ec2:StopInstances on the tagged instances. The plugin also refuses to act on any instance without the tag.

Pair it with an idle-stop job, so that "power on" is the only thing a user ever has to do.