func addToolsVersionForMachine(machine description.Machine, usedVersions map[version.Binary]bool) {
	tools := machine.Tools()
	usedVersions[tools.Version()] = true
	for _, container := range machine.Containers() {
		addToolsVersionForMachine(container, usedVersions)
	}
}

func (i *importer) machinePortsOps(m description.Machine) []txn.Op {
	var result []txn.Op
	machineId := m.Id()

	for _, ports := range m.NetworkPorts() {
		networkName := ports.NetworkName()
		doc := &portsDoc{
			MachineID:   machineId,
			NetworkName: networkName,
		}
		for _, opened := range ports.OpenPorts() {
			doc.Ports = append(doc.Ports, PortRange{
				UnitName: opened.UnitName(),
				FromPort: opened.FromPort(),
				ToPort:   opened.ToPort(),
				Protocol: opened.Protocol(),
			})
		}
		result = append(result, txn.Op{
			C:      openedPortsC,
			Id:     portsGlobalKey(machineId, networkName),
			Assert: txn.DocMissing,
			Insert: doc,
		})
	}

	return result
}

func (i *importer) importMachineBlockDevices(machine *Machine, m description.Machine) error {
	var devices []BlockDeviceInfo
	for _, device := range m.BlockDevices() {
		devices = append(devices, BlockDeviceInfo{
			DeviceName:     device.Name(),
			DeviceLinks:    device.Links(),
			Label:          device.Label(),
			UUID:           device.UUID(),
			HardwareId:     device.HardwareID(),
			BusAddress:     device.BusAddress(),
			Size:           device.Size(),
			FilesystemType: device.FilesystemType(),
			InUse:          device.InUse(),
			MountPoint:     device.MountPoint(),
		})
	}

	if err := machine.SetMachineBlockDevices(devices...); err != nil {
		return errors.Trace(err)
	}
	return nil
}

func (i *importer) makeMachineDoc(m description.Machine) (*machineDoc, error) {
	id := m.Id()
	supported, supportedSet := m.SupportedContainers()
	supportedContainers := make([]instance.ContainerType, len(supported))
	for j, c := range supported {
		supportedContainers[j] = instance.ContainerType(c)
	}
	jobs, err := i.makeMachineJobs(m.Jobs())
	if err != nil {
		return nil, errors.Trace(err)
	}
	return &machineDoc{
		DocID:                    i.st.docID(id),
		Id:                       id,
		ModelUUID:                i.st.ModelUUID(),
		Nonce:                    m.Nonce(),
		Series:                   m.Series(),
		ContainerType:            m.ContainerType(),
		Principals:               nil, // TODO
		Life:                     Alive,
		Tools:                    i.makeTools(m.Tools()),
		Jobs:                     jobs,
		NoVote:                   true,  // State servers can't be migrated yet.
		HasVote:                  false, // State servers can't be migrated yet.
		PasswordHash:             m.PasswordHash(),
		Clean:                    true, // check this later
		Addresses:                i.makeAddresses(m.ProviderAddresses()),
		MachineAddresses:         i.makeAddresses(m.MachineAddresses()),
		PreferredPrivateAddress:  i.makeAddress(m.PreferredPrivateAddress()),
		PreferredPublicAddress:   i.makeAddress(m.PreferredPublicAddress()),
		SupportedContainersKnown: supportedSet,
		SupportedContainers:      supportedContainers,
		Placement:                m.Placement(),
	}, nil
}

func (i *importer) machine(m description.Machine) error {
	// Import this machine, then import its containers.
	i.logger.Debugf("importing machine %s", m.Id())

	// 1. construct a machineDoc
	mdoc, err := i.makeMachineDoc(m)
	if err != nil {
		return errors.Annotatef(err, "machine %s", m.Id())
	}
	// 2. construct enough MachineTemplate to pass into 'insertNewMachineOps'
	//    - adds constraints doc
	//    - adds status doc
	//    - adds requested network doc
	//    - adds machine block devices doc

	// TODO: consider filesystems and volumes
	mStatus := m.Status()
	if mStatus == nil {
		return errors.NotValidf("missing status")
	}
	machineStatusDoc := statusDoc{
		ModelUUID:  i.st.ModelUUID(),
		Status:     status.Status(mStatus.Value()),
		StatusInfo: mStatus.Message(),
		StatusData: mStatus.Data(),
		Updated:    mStatus.Updated().UnixNano(),
	}
	// XXX(mjs) - this needs to be included in the serialized model
	// (a card exists for the work). Fake it for now.
	instanceStatusDoc := statusDoc{
		ModelUUID: i.st.ModelUUID(),
		Status:    status.StatusStarted,
	}
	cons := i.constraints(m.Constraints())
	networks := []string{}
	prereqOps, machineOp := i.st.baseNewMachineOps(mdoc, machineStatusDoc,
		instanceStatusDoc, cons, networks)

	// 3. create op for adding in instance data
	if instance := m.Instance(); instance != nil {
		prereqOps = append(prereqOps, i.machineInstanceOp(mdoc, instance))
	}

	if parentId := ParentId(mdoc.Id); parentId != "" {
		prereqOps = append(prereqOps,
			// Update containers record for host machine.
			i.st.addChildToContainerRefOp(parentId, mdoc.Id),
		)
	}
	// insertNewContainerRefOp adds an empty doc into the containerRefsC
	// collection for the machine being added.
	prereqOps = append(prereqOps, i.st.insertNewContainerRefOp(mdoc.Id))

	// 4. gather prereqs and machine op, run ops.
	ops := append(prereqOps, machineOp)

	// 5. add any ops that we may need to add the opened ports information.
	ops = append(ops, i.machinePortsOps(m)...)

	if err := i.st.runTransaction(ops); err != nil {
		return errors.Trace(err)
	}

	machine := newMachine(i.st, mdoc)
	if annotations := m.Annotations(); len(annotations) > 0 {
		if err := i.st.SetAnnotations(machine, annotations); err != nil {
			return errors.Trace(err)
		}
	}
	if err := i.importStatusHistory(machine.globalKey(), m.StatusHistory()); err != nil {
		return errors.Trace(err)
	}

	// Now that this machine exists in the database, process each of the
	// containers in this machine.
	for _, container := range m.Containers() {
		if err := i.machine(container); err != nil {
			return errors.Annotate(err, container.Id())
		}
	}
	return nil
}

func (e *exporter) newMachine(exParent description.Machine, machine *Machine, instances map[string]instanceData, portsData []portsDoc) (description.Machine, error) {
	args := description.MachineArgs{
		Id:            machine.MachineTag(),
		Nonce:         machine.doc.Nonce,
		PasswordHash:  machine.doc.PasswordHash,
		Placement:     machine.doc.Placement,
		Series:        machine.doc.Series,
		ContainerType: machine.doc.ContainerType,
	}

	if supported, ok := machine.SupportedContainers(); ok {
		containers := make([]string, len(supported))
		for i, containerType := range supported {
			containers[i] = string(containerType)
		}
		args.SupportedContainers = &containers
	}

	for _, job := range machine.Jobs() {
		args.Jobs = append(args.Jobs, job.MigrationValue())
	}

	// A null value means that we don't yet know which containers
	// are supported. An empty slice means 'no containers are supported'.
	var exMachine description.Machine
	if exParent == nil {
		exMachine = e.model.AddMachine(args)
	} else {
		exMachine = exParent.AddContainer(args)
	}
	exMachine.SetAddresses(
		e.newAddressArgsSlice(machine.doc.MachineAddresses),
		e.newAddressArgsSlice(machine.doc.Addresses))
	exMachine.SetPreferredAddresses(
		e.newAddressArgs(machine.doc.PreferredPublicAddress),
		e.newAddressArgs(machine.doc.PreferredPrivateAddress))

	// We fully expect the machine to have tools set, and that there is
	// some instance data.
	instData, found := instances[machine.doc.Id]
	if !found {
		return nil, errors.NotValidf("missing instance data for machine %s", machine.Id())
	}
	exMachine.SetInstance(e.newCloudInstanceArgs(instData))

	// Find the current machine status.
	globalKey := machine.globalKey()
	statusArgs, err := e.statusArgs(globalKey)
	if err != nil {
		return nil, errors.Annotatef(err, "status for machine %s", machine.Id())
	}
	exMachine.SetStatus(statusArgs)
	exMachine.SetStatusHistory(e.statusHistoryArgs(globalKey))

	tools, err := machine.AgentTools()
	if err != nil {
		// This means the tools aren't set, but they should be.
		return nil, errors.Trace(err)
	}

	exMachine.SetTools(description.AgentToolsArgs{
		Version: tools.Version,
		URL:     tools.URL,
		SHA256:  tools.SHA256,
		Size:    tools.Size,
	})

	for _, args := range e.networkPortsArgsForMachine(machine.Id(), portsData) {
		exMachine.AddNetworkPorts(args)
	}

	exMachine.SetAnnotations(e.getAnnotations(globalKey))

	constraintsArgs, err := e.constraintsArgs(globalKey)
	if err != nil {
		return nil, errors.Trace(err)
	}
	exMachine.SetConstraints(constraintsArgs)

	return exMachine, nil
}