kubernetes.go

/*
Copyright 2018 The Doctl Authors All rights reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
	http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package commands

import (
	"errors"
	"fmt"
	"strconv"
	"strings"

	"github.com/digitalocean/doctl"
	"github.com/digitalocean/doctl/commands/displayers"
	"github.com/digitalocean/doctl/do"
	"github.com/digitalocean/godo"
	"github.com/pborman/uuid"
	"github.com/spf13/cobra"
)

// Kubernetes creates the kubernetes command.
func Kubernetes() *Command {
	cmd := &Command{
		Command: &cobra.Command{
			Use:     "kubernetes",
			Aliases: []string{"kube", "k8s", "k"},
			Short:   "[beta] kubernetes commands",
			Long:    "[beta] kubernetes is used to access Kubernetes commands",
			Hidden:  !isBeta(),
		},
	}

	CmdBuilder(cmd, RunKubernetesGet, "get <id|name>", "get a cluster", Writer, aliasOpt("g"))

	CmdBuilder(cmd, RunKubernetesGetKubeconfig, "kubeconfig <id|name>", "get a cluster's kubeconfig file", Writer, aliasOpt("cfg"))

	CmdBuilder(cmd, RunKubernetesList, "list", "get a list of your clusters", Writer, aliasOpt("ls"))

	cmdKubeClusterCreate := CmdBuilder(cmd, RunKubernetesCreate, "create", "create a cluster", Writer, aliasOpt("c"))
	AddStringFlag(cmdKubeClusterCreate, doctl.ArgClusterName, "", "", "cluster name", requiredOpt())
	AddStringFlag(cmdKubeClusterCreate, doctl.ArgRegionSlug, "", "", "cluster region location, example value: nyc1", requiredOpt())
	AddStringFlag(cmdKubeClusterCreate, doctl.ArgClusterVersionSlug, "", "", "cluster version", requiredOpt())
	AddStringSliceFlag(cmdKubeClusterCreate, doctl.ArgTagNames, "", nil, "cluster tags")
	AddStringSliceFlag(cmdKubeClusterCreate, doctl.ArgClusterNodePools, "", nil, `cluster node pools in the form "name=your-name;size=droplet_size;count=5;tag=tag1;tag=tag2"`, requiredOpt())

	cmdKubeClusterUpdate := CmdBuilder(cmd, RunKubernetesUpdate, "update <id|name>", "update a cluster's properties", Writer, aliasOpt("u"))
	AddStringFlag(cmdKubeClusterUpdate, doctl.ArgClusterName, "", "", "cluster name")
	AddStringSliceFlag(cmdKubeClusterUpdate, doctl.ArgTagNames, "", nil, "cluster tags")

	cmdKubeClusterDelete := CmdBuilder(cmd, RunKubernetesDelete, "delete <id|name>", "delete a cluster", Writer, aliasOpt("d", "rm"))
	AddBoolFlag(cmdKubeClusterDelete, doctl.ArgForce, doctl.ArgShortForce, false, "Force cluster delete")

	nodePoolCmd := &Command{
		Command: &cobra.Command{
			Use:     "node-pool",
			Aliases: []string{"pool", "np", "p"},
			Short:   "node pool commands",
			Long:    "node pool commands are used to act on a cluster's node pools",
		},
	}

	CmdBuilder(nodePoolCmd, RunClusterNodePoolGet, "get <cluster-id|cluster-name> <pool-id|pool-name>", "get a cluster's node pool", Writer, aliasOpt("g"))
	CmdBuilder(nodePoolCmd, RunClusterNodePoolList, "list <cluster-id|cluster-name>", "list a cluster's node pools", Writer, aliasOpt("ls"))

	cmdKubeNodePoolCreate := CmdBuilder(nodePoolCmd, RunClusterNodePoolCreate, "create <cluster-id|cluster-name>", "create a new node pool for a cluster", Writer, aliasOpt("c"))
	AddStringFlag(cmdKubeNodePoolCreate, doctl.ArgNodePoolName, "", "", "node pool name", requiredOpt())
	AddStringFlag(cmdKubeNodePoolCreate, doctl.ArgSizeSlug, "", "", "size of nodes in the node pool", requiredOpt())
	AddStringFlag(cmdKubeNodePoolCreate, doctl.ArgNodePoolCount, "", "", "count of nodes in the node pool", requiredOpt())
	AddStringFlag(cmdKubeNodePoolCreate, doctl.ArgTagNames, "", "", "tags to apply to the node pool")

	cmdKubeNodePoolUpdate := CmdBuilder(nodePoolCmd, RunClusterNodePoolUpdate, "update <cluster-id|cluster-name> <pool-id|pool-name>", "update an existing node pool in a cluster", Writer, aliasOpt("u"))
	AddStringFlag(cmdKubeNodePoolUpdate, doctl.ArgNodePoolName, "", "", "node pool name")
	AddStringFlag(cmdKubeNodePoolUpdate, doctl.ArgNodePoolCount, "", "", "count of nodes in the node pool")
	AddStringFlag(cmdKubeNodePoolUpdate, doctl.ArgTagNames, "", "", "tags to apply to the node pool")

	cmdKubeNodePoolRecycle := CmdBuilder(nodePoolCmd, RunClusterNodePoolRecycle, "recycle <cluster-id|cluster-name> <pool-id|pool-name>", "recycle nodes in a node pool", Writer, aliasOpt("r"))
	AddStringFlag(cmdKubeNodePoolRecycle, doctl.ArgNodePoolNodeIDs, "", "", "ID or name of the nodes in the node pool to recycle")

	cmdKubeNodePoolDelete := CmdBuilder(nodePoolCmd, RunClusterNodePoolDelete, "delete <cluster-id|cluster-name> <pool-id|pool-name>", "delete node pool from a cluster", Writer, aliasOpt("d", "rm"))
	AddBoolFlag(cmdKubeNodePoolDelete, doctl.ArgForce, doctl.ArgShortForce, false, "Force node pool delete")

	cmd.AddCommand(nodePoolCmd)

	optionsCmd := &Command{
		Command: &cobra.Command{
			Use:     "options",
			Aliases: []string{"opts", "o"},
			Short:   "options commands",
			Long:    "options commands are used to find options for Kubernetes clusters",
		},
	}

	CmdBuilder(optionsCmd, RunKubeOptionsListVersion, "versions", "versions that can be used to create a Kubernetes cluster", Writer, aliasOpt("v"))

	cmd.AddCommand(optionsCmd)

	return cmd
}

// Clusters

// RunKubernetesGet retrieves an existing kubernetes by its identifier.
func RunKubernetesGet(c *CmdConfig) error {
	if len(c.Args) != 1 {
		return doctl.NewMissingArgsErr(c.NS)
	}
	clusterIDorName := c.Args[0]

	cluster, err := clusterByIDorName(c.Kubernetes(), clusterIDorName)
	if err != nil {
		return err
	}
	return displayClusters(c, *cluster)
}

// RunKubernetesGetKubeconfig retrieves an existing kubernetes by its identifier.
func RunKubernetesGetKubeconfig(c *CmdConfig) error {
	if len(c.Args) != 1 {
		return doctl.NewMissingArgsErr(c.NS)
	}
	clusterID, err := clusterIDize(c.Kubernetes(), c.Args[0])
	if err != nil {
		return err
	}

	kube := c.Kubernetes()
	kubeconfig, err := kube.GetKubeConfig(clusterID)
	if err != nil {
		return err
	}

	// TODO: better integration with existing kubeconfig file
	_, err = c.Out.Write(kubeconfig)
	return err
}

// RunKubernetesList lists kubernetess.
func RunKubernetesList(c *CmdConfig) error {
	kube := c.Kubernetes()
	list, err := kube.List()
	if err != nil {
		return err
	}

	return displayClusters(c, list...)
}

// RunKubernetesCreate creates a new kubernetes with a given configuration.
func RunKubernetesCreate(c *CmdConfig) error {
	r := new(godo.KubernetesClusterCreateRequest)
	if err := buildClusterCreateRequestFromArgs(c, r); err != nil {
		return err
	}

	kube := c.Kubernetes()

	cluster, err := kube.Create(r)
	if err != nil {
		return err
	}

	return displayClusters(c, *cluster)
}

// RunKubernetesUpdate updates an existing kubernetes with new configuration.
func RunKubernetesUpdate(c *CmdConfig) error {
	if len(c.Args) == 0 {
		return doctl.NewMissingArgsErr(c.NS)
	}
	clusterID, err := clusterIDize(c.Kubernetes(), c.Args[0])
	if err != nil {
		return err
	}

	r := new(godo.KubernetesClusterUpdateRequest)
	if err := buildClusterUpdateRequestFromArgs(c, r); err != nil {
		return err
	}

	kube := c.Kubernetes()
	cluster, err := kube.Update(clusterID, r)
	if err != nil {
		return err
	}

	return displayClusters(c, *cluster)
}

// RunKubernetesDelete deletes a kubernetes by its identifier.
func RunKubernetesDelete(c *CmdConfig) error {
	if len(c.Args) != 1 {
		return doctl.NewMissingArgsErr(c.NS)
	}
	clusterID, err := clusterIDize(c.Kubernetes(), c.Args[0])
	if err != nil {
		return err
	}

	force, err := c.Doit.GetBool(c.NS, doctl.ArgForce)
	if err != nil {
		return err
	}

	if force || AskForConfirm("delete this Kubernetes cluster") == nil {
		kube := c.Kubernetes()
		if err := kube.Delete(clusterID); err != nil {
			return err
		}
	} else {
		return fmt.Errorf("operation aborted")
	}

	return nil
}

// Node Pools

// RunClusterNodePoolGet retrieves an existing cluster node pool by its identifier.
func RunClusterNodePoolGet(c *CmdConfig) error {
	if len(c.Args) != 2 {
		return doctl.NewMissingArgsErr(c.NS)
	}
	clusterID, err := clusterIDize(c.Kubernetes(), c.Args[0])
	if err != nil {
		return err
	}
	nodePool, err := poolByIDorName(c.Kubernetes(), clusterID, c.Args[1])
	if err != nil {
		return err
	}
	return displayNodePools(c, *nodePool)
}

// RunClusterNodePoolList lists cluster node pool.
func RunClusterNodePoolList(c *CmdConfig) error {
	if len(c.Args) != 1 {
		return doctl.NewMissingArgsErr(c.NS)
	}
	clusterID, err := clusterIDize(c.Kubernetes(), c.Args[0])
	if err != nil {
		return err
	}
	kube := c.Kubernetes()
	list, err := kube.ListNodePools(clusterID)
	if err != nil {
		return err
	}

	return displayNodePools(c, list...)
}

// RunClusterNodePoolCreate creates a new cluster node pool with a given configuration.
func RunClusterNodePoolCreate(c *CmdConfig) error {
	if len(c.Args) != 1 {
		return doctl.NewMissingArgsErr(c.NS)
	}
	clusterID, err := clusterIDize(c.Kubernetes(), c.Args[0])
	if err != nil {
		return err
	}

	r := new(godo.KubernetesNodePoolCreateRequest)
	if err := buildNodePoolCreateRequestFromArgs(c, r); err != nil {
		return err
	}

	kube := c.Kubernetes()
	nodePool, err := kube.CreateNodePool(clusterID, r)
	if err != nil {
		return err
	}

	return displayNodePools(c, *nodePool)
}

// RunClusterNodePoolUpdate updates an existing cluster node pool with new properties.
func RunClusterNodePoolUpdate(c *CmdConfig) error {
	if len(c.Args) != 2 {
		return doctl.NewMissingArgsErr(c.NS)
	}
	clusterID, err := clusterIDize(c.Kubernetes(), c.Args[0])
	if err != nil {
		return err
	}
	poolID, err := poolIDize(c.Kubernetes(), clusterID, c.Args[1])
	if err != nil {
		return err
	}

	r := new(godo.KubernetesNodePoolUpdateRequest)
	if err := buildNodePoolUpdateRequestFromArgs(c, r); err != nil {
		return err
	}

	kube := c.Kubernetes()
	nodePool, err := kube.UpdateNodePool(clusterID, poolID, r)
	if err != nil {
		return err
	}

	return displayNodePools(c, *nodePool)
}

// RunClusterNodePoolRecycle recycles an existing kubernetes with new configuration.
func RunClusterNodePoolRecycle(c *CmdConfig) error {
	if len(c.Args) != 2 {
		return doctl.NewMissingArgsErr(c.NS)
	}
	clusterID, err := clusterIDize(c.Kubernetes(), c.Args[0])
	if err != nil {
		return err
	}
	poolID, err := poolIDize(c.Kubernetes(), clusterID, c.Args[1])
	if err != nil {
		return err
	}

	r := new(godo.KubernetesNodePoolRecycleNodesRequest)
	if err := buildNodePoolRecycleRequestFromArgs(c, clusterID, poolID, r); err != nil {
		return err
	}

	kube := c.Kubernetes()
	return kube.RecycleNodePoolNodes(clusterID, poolID, r)
}

// RunClusterNodePoolDelete deletes a kubernetes by its identifier.
func RunClusterNodePoolDelete(c *CmdConfig) error {
	if len(c.Args) != 2 {
		return doctl.NewMissingArgsErr(c.NS)
	}
	clusterID, err := clusterIDize(c.Kubernetes(), c.Args[0])
	if err != nil {
		return err
	}
	poolID, err := poolIDize(c.Kubernetes(), clusterID, c.Args[1])
	if err != nil {
		return err
	}

	kube := c.Kubernetes()
	return kube.DeleteNodePool(clusterID, poolID)
}

// RunKubeOptionsListVersion deletes a kubernetes by its identifier.
func RunKubeOptionsListVersion(c *CmdConfig) error {

	kube := c.Kubernetes()
	versions, err := kube.GetVersions()
	if err != nil {
		return err
	}
	item := &displayers.KubernetesVersions{KubernetesVersions: versions}
	return c.Display(item)
}

func buildClusterCreateRequestFromArgs(c *CmdConfig, r *godo.KubernetesClusterCreateRequest) error {
	name, err := c.Doit.GetString(c.NS, doctl.ArgClusterName)
	if err != nil {
		return err
	}
	r.Name = name

	region, err := c.Doit.GetString(c.NS, doctl.ArgRegionSlug)
	if err != nil {
		return err
	}
	r.RegionSlug = region

	version, err := c.Doit.GetString(c.NS, doctl.ArgClusterVersionSlug)
	if err != nil {
		return err
	}
	r.VersionSlug = version

	tags, err := c.Doit.GetStringSlice(c.NS, doctl.ArgTagNames)
	if err != nil {
		return err
	}
	r.Tags = tags

	nodePools, err := buildNodePoolCreateRequestsFromArgs(c)
	if err != nil {
		return err
	}
	r.NodePools = nodePools

	return nil
}

func buildClusterUpdateRequestFromArgs(c *CmdConfig, r *godo.KubernetesClusterUpdateRequest) error {
	name, err := c.Doit.GetString(c.NS, doctl.ArgClusterName)
	if err != nil {
		return err
	}
	r.Name = name

	tags, err := c.Doit.GetStringSlice(c.NS, doctl.ArgTagNames)
	if err != nil {
		return err
	}
	r.Tags = tags

	return nil
}

func buildNodePoolRecycleRequestFromArgs(c *CmdConfig, clusterID, poolID string, r *godo.KubernetesNodePoolRecycleNodesRequest) error {
	nodeIDorNames, err := c.Doit.GetStringSlice(c.NS, doctl.ArgNodePoolNodeIDs)
	if err != nil {
		return err
	}
	allUUIDs := true
	for _, node := range nodeIDorNames {
		if !looksLikeUUID(node) {
			allUUIDs = false
		}
	}
	if allUUIDs {
		r.Nodes = nodeIDorNames
	} else {
		// at least some of the args weren't UUIDs, so assume that they're all names
		nodes, err := nodesByNames(c.Kubernetes(), clusterID, poolID, nodeIDorNames)
		if err != nil {
			return err
		}
		for _, node := range nodes {
			r.Nodes = append(r.Nodes, node.ID)
		}
	}
	return nil
}

func buildNodePoolCreateRequestsFromArgs(c *CmdConfig) ([]*godo.KubernetesNodePoolCreateRequest, error) {
	nodePools, err := c.Doit.GetStringSlice(c.NS, doctl.ArgClusterNodePools)
	if err != nil {
		return nil, err
	}
	out := make([]*godo.KubernetesNodePoolCreateRequest, 0, len(nodePools))
	for i, nodePoolString := range nodePools {
		poolCreateReq, err := parseNodePoolString(nodePoolString)
		if err != nil {
			return nil, fmt.Errorf("invalid node pool arguments for flag %d: %v", i, err)
		}
		out = append(out, poolCreateReq)
	}
	return out, nil
}

func parseNodePoolString(nodePool string) (*godo.KubernetesNodePoolCreateRequest, error) {
	const (
		argSeparator = ";"
		kvSeparator  = "="
	)
	out := new(godo.KubernetesNodePoolCreateRequest)
	for _, arg := range strings.Split(nodePool, argSeparator) {
		kvs := strings.SplitN(arg, kvSeparator, 2)
		if len(kvs) < 2 {
			return nil, fmt.Errorf("a node pool string argument must be of the form `key=value`, got KVs %v", kvs)
		}
		key := kvs[0]
		value := kvs[1]
		switch key {
		case "name":
			out.Name = value
		case "size":
			out.Size = value
		case "count":
			count, err := strconv.ParseInt(value, 10, 64)
			if err != nil {
				return nil, errors.New("node pool count argument must be a valid integer")
			}
			out.Count = int(count)
		case "tag":
			out.Tags = append(out.Tags, value)
		default:
			return nil, fmt.Errorf("unsupported node pool argument %q", key)
		}
	}
	return out, nil
}

func buildNodePoolCreateRequestFromArgs(c *CmdConfig, r *godo.KubernetesNodePoolCreateRequest) error {
	name, err := c.Doit.GetString(c.NS, doctl.ArgNodePoolName)
	if err != nil {
		return err
	}
	r.Name = name

	size, err := c.Doit.GetString(c.NS, doctl.ArgSizeSlug)
	if err != nil {
		return err
	}
	r.Size = size

	count, err := c.Doit.GetInt(c.NS, doctl.ArgNodePoolCount)
	if err != nil {
		return err
	}
	r.Count = count

	tags, err := c.Doit.GetStringSlice(c.NS, doctl.ArgTagNames)
	if err != nil {
		return err
	}
	r.Tags = tags

	return nil
}

func buildNodePoolUpdateRequestFromArgs(c *CmdConfig, r *godo.KubernetesNodePoolUpdateRequest) error {
	name, err := c.Doit.GetString(c.NS, doctl.ArgNodePoolName)
	if err != nil {
		return err
	}
	r.Name = name

	count, err := c.Doit.GetInt(c.NS, doctl.ArgNodePoolCount)
	if err != nil {
		return err
	}
	r.Count = count

	tags, err := c.Doit.GetStringSlice(c.NS, doctl.ArgTagNames)
	if err != nil {
		return err
	}
	r.Tags = tags

	return nil
}

func displayClusters(c *CmdConfig, clusters ...do.KubernetesCluster) error {
	item := &displayers.KubernetesClusters{KubernetesClusters: do.KubernetesClusters(clusters)}
	return c.Display(item)
}

func displayNodePools(c *CmdConfig, nodePools ...do.KubernetesNodePool) error {
	item := &displayers.KubernetesNodePools{KubernetesNodePools: do.KubernetesNodePools(nodePools)}
	return c.Display(item)
}

// clusterByIDorName attempts to find a cluster by ID or by name if the argument isn't an ID. If multiple
// clusters have the same name, then an error with the cluster IDs matching this name is returned.
func clusterByIDorName(kube do.KubernetesService, idOrName string) (*do.KubernetesCluster, error) {
	if looksLikeUUID(idOrName) {
		clusterID := idOrName
		return kube.Get(clusterID)
	}
	clusters, err := kube.List()
	if err != nil {
		return nil, err
	}
	var out []*do.KubernetesCluster
	for _, c := range clusters {
		if c.Name == idOrName {
			out = append(out, &c)
		}
	}
	switch {
	case len(out) == 0:
		return nil, fmt.Errorf("no cluster goes by the name %q", idOrName)
	case len(out) > 1:
		var ids []string
		for _, c := range out {
			ids = append(ids, c.ID)
		}
		return nil, fmt.Errorf("many clusters go by the name %q, they have the following IDs: %v", idOrName, ids)
	default:
		if len(out) != 1 {
			panic("the default case should always have len(out) == 1")
		}
		return out[0], nil
	}
}

// clusterIDize attempts to make a cluster ID/name string be a cluster ID.
// use this as opposed to `clusterByIDorName` if you just care about getting
// a cluster ID and don't need the cluster object itself
func clusterIDize(kube do.KubernetesService, idOrName string) (string, error) {
	if looksLikeUUID(idOrName) {
		return idOrName, nil
	}
	clusters, err := kube.List()
	if err != nil {
		return "", err
	}
	var ids []string
	for _, c := range clusters {
		if c.Name == idOrName {
			ids = append(ids, c.ID)
		}
	}
	switch {
	case len(ids) == 0:
		return "", fmt.Errorf("no cluster goes by the name %q", idOrName)
	case len(ids) > 1:
		return "", fmt.Errorf("many clusters go by the name %q, they have the following IDs: %v", idOrName, ids)
	default:
		if len(ids) != 1 {
			panic("the default case should always have len(ids) == 1")
		}
		return ids[0], nil
	}
}

// poolByIDorName attempts to find a pool by ID or by name if the argument isn't an ID. If multiple
// pools have the same name, then an error with the pool IDs matching this name is returned.
func poolByIDorName(kube do.KubernetesService, clusterID, idOrName string) (*do.KubernetesNodePool, error) {
	if looksLikeUUID(idOrName) {
		poolID := idOrName
		return kube.GetNodePool(clusterID, poolID)
	}
	nodePools, err := kube.ListNodePools(clusterID)
	if err != nil {
		return nil, err
	}
	var out []*do.KubernetesNodePool
	for _, c := range nodePools {
		if c.Name == idOrName {
			out = append(out, &c)
		}
	}
	switch {
	case len(out) == 0:
		return nil, fmt.Errorf("no node pool goes by the name %q", idOrName)
	case len(out) > 1:
		var ids []string
		for _, c := range out {
			ids = append(ids, c.ID)
		}
		return nil, fmt.Errorf("many node pools go by the name %q, they have the following IDs: %v", idOrName, ids)
	default:
		if len(out) != 1 {
			panic("the default case should always have len(out) == 1")
		}
		return out[0], nil
	}
}

// poolIDize attempts to make a node pool ID/name string be a node pool ID.
// use this as opposed to `poolByIDorName` if you just care about getting
// a node pool ID and don't need the node pool object itself
func poolIDize(kube do.KubernetesService, clusterID, idOrName string) (string, error) {
	if looksLikeUUID(idOrName) {
		return idOrName, nil
	}
	pools, err := kube.ListNodePools(clusterID)
	if err != nil {
		return "", err
	}
	var ids []string
	for _, c := range pools {
		if c.Name == idOrName {
			ids = append(ids, c.ID)
		}
	}
	switch {
	case len(ids) == 0:
		return "", fmt.Errorf("no node pool goes by the name %q", idOrName)
	case len(ids) > 1:
		return "", fmt.Errorf("many node pools go by the name %q, they have the following IDs: %v", idOrName, ids)
	default:
		if len(ids) != 1 {
			panic("the default case should always have len(ids) == 1")
		}
		return ids[0], nil
	}
}

// nodesByNames attempts to find nodes by names. If multiple nodes have the same name,
// then an error with the node IDs matching this name is returned.
func nodesByNames(kube do.KubernetesService, clusterID, poolID string, nodeNames []string) ([]*godo.KubernetesNode, error) {
	nodePool, err := kube.GetNodePool(clusterID, poolID)
	if err != nil {
		return nil, err
	}
	var out []*godo.KubernetesNode
	for _, name := range nodeNames {
		node, err := nodeByName(name, nodePool.Nodes)
		if err != nil {
			return nil, err
		}
		out = append(out, node)
	}
	return out, nil
}

func nodeByName(name string, nodes []*godo.KubernetesNode) (*godo.KubernetesNode, error) {
	var out []*godo.KubernetesNode
	for _, n := range nodes {
		if n.Name == name {
			out = append(out, n)
		}
	}
	switch {
	case len(out) == 0:
		return nil, fmt.Errorf("no node goes by the name %q", name)
	case len(out) > 1:
		var ids []string
		for _, c := range out {
			ids = append(ids, c.ID)
		}
		return nil, fmt.Errorf("many nodes go by the name %q, they have the following IDs: %v", name, ids)
	default:
		if len(out) != 1 {
			panic("the default case should always have len(out) == 1")
		}
		return out[0], nil
	}
}

func looksLikeUUID(str string) bool {
	return uuid.Parse(str) != nil
}