This package owns the cross-process contract used to direct a command to the node that owns a running EC2 instance. It is not an in-process service interface or the owner of instance state.

Route and purpose

The subject is ec2.cmd.<instance-id>. It is request/reply, and the daemon that hosts that instance's QEMU process is the only subscriber. This route exists because lifecycle operations such as start, stop, terminate, volume attach/detach and ENI attach/detach must reach that one process; sending them through the normal daemon queue group could select a different node.

InstanceCommandSubject constructs a targeted subject. The corresponding subscription and permission pattern is ec2.cmd.*: the * deliberately matches exactly one final instance-ID token, not an arbitrary descendant.

Compatibility boundary

EC2InstanceCommand, its nested data objects, their JSON field names and the subject shape are wire compatibility. Callers and receivers must use this package rather than rebuild those details. commands_test.go preserves the version-1 JSON shape and subject form.

This package owns shared command payloads and the drain-volume response. It does not define every action's reply body, authorize the request, store EC2 state or implement NATS transport. Those remain responsibilities of the EC2 domain and its runtime composition.

Any incompatible subject or payload change requires an explicit versioned contract or an approved compatibility plan; it is not a package refactor.

Internet gateway projection

InternetGatewayEvent carries the EC2 domain's authorized projection of an internet-gateway attachment or detachment into the network data plane. It is published on vpc.igw-attach or vpc.igw-detach, then consumed by the network subscriber to create or remove the OVN gateway realization. The EC2 domain owns the AWS-visible attachment semantics; the network domain owns the OVN work.

The event intentionally contains only the gateway and VPC identifiers. It is not permission to read EC2's private VPC or IGW state. The JSON and both subjects are compatibility-tested in igw_test.go.