linkerd2/cli/cmd/stat.go

package cmd

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"os"
	"sort"
	"strings"
	"text/tabwriter"
	"time"

	"github.com/linkerd/linkerd2/controller/api/util"
	pb "github.com/linkerd/linkerd2/controller/gen/public"
	"github.com/linkerd/linkerd2/pkg/k8s"
	log "github.com/sirupsen/logrus"
	"github.com/spf13/cobra"
)

type statOptions struct {
	statOptionsBase
	toNamespace   string
	toResource    string
	fromNamespace string
	fromResource  string
	allNamespaces bool
	labelSelector string
	unmeshed      bool
}

type indexedResults struct {
	ix   int
	rows []*pb.StatTable_PodGroup_Row
	err  error
}

func newStatOptions() *statOptions {
	return &statOptions{
		statOptionsBase: *newStatOptionsBase(),
		toNamespace:     "",
		toResource:      "",
		fromNamespace:   "",
		fromResource:    "",
		allNamespaces:   false,
		labelSelector:   "",
		unmeshed:        false,
	}
}

func newCmdStat() *cobra.Command {
	options := newStatOptions()

	cmd := &cobra.Command{
		Use:   "stat [flags] (RESOURCES)",
		Short: "Display traffic stats about one or many resources",
		Long: `Display traffic stats about one or many resources.

  The RESOURCES argument specifies the target resource(s) to aggregate stats over:
  (TYPE [NAME] | TYPE/NAME)
  or (TYPE [NAME1] [NAME2]...)
  or (TYPE1/NAME1 TYPE2/NAME2...)

  Examples:
  * cronjob/my-cronjob
  * deploy
  * deploy/my-deploy
  * deploy/ po/
  * ds/my-daemonset
  * job/my-job
  * ns/my-ns
  * po/mypod1 rc/my-replication-controller
  * po mypod1 mypod2
  * rc/my-replication-controller
  * rs
  * rs/my-replicaset
  * sts/my-statefulset
  * ts/my-split
  * authority
  * au/my-authority
  * all

  Valid resource types include:
  * cronjobs
  * daemonsets
  * deployments
  * namespaces
  * jobs
  * pods
  * replicasets
  * replicationcontrollers
  * statefulsets
  * trafficsplits
  * authorities (not supported in --from)
  * services (only supported if a --from is also specified, or as a --to)
  * all (all resource types, not supported in --from or --to)

This command will hide resources that have completed, such as pods that are in the Succeeded or Failed phases.
If no resource name is specified, displays stats about all resources of the specified RESOURCETYPE`,
		Example: `  # Get all deployments in the test namespace.
  linkerd stat deployments -n test

  # Get the hello1 replication controller in the test namespace.
  linkerd stat replicationcontrollers hello1 -n test

  # Get all namespaces.
  linkerd stat namespaces

  # Get all inbound stats to the web deployment.
  linkerd stat deploy/web

  # Get all inbound stats to the pod1 and pod2 pods
  linkerd stat po pod1 pod2

  # Get all inbound stats to the pod1 pod and the web deployment
  linkerd stat po/pod1 deploy/web

  # Get all pods in all namespaces that call the hello1 deployment in the test namespace.
  linkerd stat pods --to deploy/hello1 --to-namespace test --all-namespaces

  # Get all pods in all namespaces that call the hello1 service in the test namespace.
  linkerd stat pods --to svc/hello1 --to-namespace test --all-namespaces

  # Get all services in all namespaces that receive calls from hello1 deployment in the test namespace.
  linkerd stat services --from deploy/hello1 --from-namespace test --all-namespaces

  # Get all trafficsplits and their leaf services.
  linkerd stat ts

  # Get the hello-split trafficsplit and its leaf services.
  linkerd stat ts/hello-split

  # Get all trafficsplits and their leaf services, and metrics for any traffic coming to the leaf services from the hello1 deployment.
  linkerd stat ts --from deploy/hello1

  # Get all namespaces that receive traffic from the default namespace.
  linkerd stat namespaces --from ns/default

  # Get all inbound stats to the test namespace.
  linkerd stat ns/test`,
		Args:      cobra.MinimumNArgs(1),
		ValidArgs: util.ValidTargets,
		RunE: func(cmd *cobra.Command, args []string) error {
			reqs, err := buildStatSummaryRequests(args, options)
			if err != nil {
				return fmt.Errorf("error creating metrics request while making stats request: %v", err)
			}

			// The gRPC client is concurrency-safe, so we can reuse it in all the following goroutines
			// https://github.com/grpc/grpc-go/issues/682
			client := checkPublicAPIClientOrExit()
			c := make(chan indexedResults, len(reqs))
			for num, req := range reqs {
				go func(num int, req *pb.StatSummaryRequest) {
					resp, err := requestStatsFromAPI(client, req)
					rows := respToRows(resp)
					c <- indexedResults{num, rows, err}
				}(num, req)
			}

			totalRows := make([]*pb.StatTable_PodGroup_Row, 0)
			i := 0
			for res := range c {
				if res.err != nil {
					return res.err
				}
				totalRows = append(totalRows, res.rows...)
				if i++; i == len(reqs) {
					close(c)
				}
			}

			output := renderStatStats(totalRows, options)
			_, err = fmt.Print(output)

			return err
		},
	}

	cmd.PersistentFlags().StringVarP(&options.namespace, "namespace", "n", options.namespace, "Namespace of the specified resource")
	cmd.PersistentFlags().StringVarP(&options.timeWindow, "time-window", "t", options.timeWindow, "Stat window (for example: \"15s\", \"1m\", \"10m\", \"1h\"). Needs to be at least 15s.")
	cmd.PersistentFlags().StringVar(&options.toResource, "to", options.toResource, "If present, restricts outbound stats to the specified resource name")
	cmd.PersistentFlags().StringVar(&options.toNamespace, "to-namespace", options.toNamespace, "Sets the namespace used to lookup the \"--to\" resource; by default the current \"--namespace\" is used")
	cmd.PersistentFlags().StringVar(&options.fromResource, "from", options.fromResource, "If present, restricts outbound stats from the specified resource name")
	cmd.PersistentFlags().StringVar(&options.fromNamespace, "from-namespace", options.fromNamespace, "Sets the namespace used from lookup the \"--from\" resource; by default the current \"--namespace\" is used")
	cmd.PersistentFlags().BoolVarP(&options.allNamespaces, "all-namespaces", "A", options.allNamespaces, "If present, returns stats across all namespaces, ignoring the \"--namespace\" flag")
	cmd.PersistentFlags().StringVarP(&options.outputFormat, "output", "o", options.outputFormat, "Output format; one of: \"table\" or \"json\" or \"wide\"")
	cmd.PersistentFlags().StringVarP(&options.labelSelector, "selector", "l", options.labelSelector, "Selector (label query) to filter on, supports '=', '==', and '!='")
	cmd.PersistentFlags().BoolVar(&options.unmeshed, "unmeshed", options.unmeshed, "If present, include unmeshed resources in the output")
	return cmd
}

func respToRows(resp *pb.StatSummaryResponse) []*pb.StatTable_PodGroup_Row {
	rows := make([]*pb.StatTable_PodGroup_Row, 0)
	if resp != nil {
		for _, statTable := range resp.GetOk().StatTables {
			rows = append(rows, statTable.GetPodGroup().Rows...)
		}
	}
	return rows
}

func requestStatsFromAPI(client pb.ApiClient, req *pb.StatSummaryRequest) (*pb.StatSummaryResponse, error) {
	resp, err := client.StatSummary(context.Background(), req)
	if err != nil {
		return nil, fmt.Errorf("StatSummary API error: %v", err)
	}
	if e := resp.GetError(); e != nil {
		return nil, fmt.Errorf("StatSummary API response error: %v", e.Error)
	}

	return resp, nil
}

func renderStatStats(rows []*pb.StatTable_PodGroup_Row, options *statOptions) string {
	var buffer bytes.Buffer
	w := tabwriter.NewWriter(&buffer, 0, 0, padding, ' ', tabwriter.AlignRight)
	writeStatsToBuffer(rows, w, options)
	w.Flush()

	return renderStats(buffer, &options.statOptionsBase)
}

const padding = 3

type rowStats struct {
	route              string
	dst                string
	requestRate        float64
	successRate        float64
	latencyP50         uint64
	latencyP95         uint64
	latencyP99         uint64
	tcpOpenConnections uint64
	tcpReadBytes       float64
	tcpWriteBytes      float64
}

type row struct {
	meshed string
	status string
	*rowStats
	*tsStats
}

type tsStats struct {
	apex   string
	leaf   string
	weight string
}

var (
	nameHeader      = "NAME"
	namespaceHeader = "NAMESPACE"
	apexHeader      = "APEX"
	leafHeader      = "LEAF"
	weightHeader    = "WEIGHT"
)

func statHasRequestData(stat *pb.BasicStats) bool {
	return stat.GetSuccessCount() != 0 || stat.GetFailureCount() != 0 || stat.GetActualSuccessCount() != 0 || stat.GetActualFailureCount() != 0
}

func isPodOwnerResource(typ string) bool {
	return typ != k8s.TrafficSplit && typ != k8s.Authority
}

func writeStatsToBuffer(rows []*pb.StatTable_PodGroup_Row, w *tabwriter.Writer, options *statOptions) {
	maxNameLength := len(nameHeader)
	maxNamespaceLength := len(namespaceHeader)
	maxApexLength := len(apexHeader)
	maxLeafLength := len(leafHeader)
	maxWeightLength := len(weightHeader)

	statTables := make(map[string]map[string]*row)

	prefixTypes := make(map[string]bool)
	for _, r := range rows {
		prefixTypes[r.Resource.Type] = true
	}
	usePrefix := false
	if len(prefixTypes) > 1 {
		usePrefix = true
	}

	for _, r := range rows {

		// Skip unmeshed pods if the unmeshed option isn't enabled.
		if !options.unmeshed && r.GetMeshedPodCount() == 0 &&
			// Skip only if the resource can own pods
			isPodOwnerResource(r.Resource.Type) &&
			// Skip only if --from isn't specified (unmeshed resources can show
			// stats in --from mode because metrics are collected on the client
			// side).
			options.fromResource == "" {
			continue
		}

		name := r.Resource.Name
		nameWithPrefix := name
		if usePrefix {
			nameWithPrefix = getNamePrefix(r.Resource.Type) + nameWithPrefix
		}

		namespace := r.Resource.Namespace
		key := fmt.Sprintf("%s/%s", namespace, name)
		if r.Resource.Type == k8s.TrafficSplit {
			key = fmt.Sprintf("%s/%s/%s", namespace, name, r.TsStats.Leaf)
		}
		resourceKey := r.Resource.Type

		if _, ok := statTables[resourceKey]; !ok {
			statTables[resourceKey] = make(map[string]*row)
		}

		if len(nameWithPrefix) > maxNameLength {
			maxNameLength = len(nameWithPrefix)
		}

		if len(namespace) > maxNamespaceLength {
			maxNamespaceLength = len(namespace)
		}

		meshedCount := fmt.Sprintf("%d/%d", r.MeshedPodCount, r.RunningPodCount)
		if resourceKey == k8s.Authority {
			meshedCount = "-"
		}
		statTables[resourceKey][key] = &row{
			meshed: meshedCount,
			status: r.Status,
		}

		if r.Stats != nil && statHasRequestData(r.Stats) {
			statTables[resourceKey][key].rowStats = &rowStats{
				requestRate:        getRequestRate(r.Stats.GetSuccessCount(), r.Stats.GetFailureCount(), r.TimeWindow),
				successRate:        getSuccessRate(r.Stats.GetSuccessCount(), r.Stats.GetFailureCount()),
				latencyP50:         r.Stats.LatencyMsP50,
				latencyP95:         r.Stats.LatencyMsP95,
				latencyP99:         r.Stats.LatencyMsP99,
				tcpOpenConnections: r.GetTcpStats().GetOpenConnections(),
				tcpReadBytes:       getByteRate(r.GetTcpStats().GetReadBytesTotal(), r.TimeWindow),
				tcpWriteBytes:      getByteRate(r.GetTcpStats().GetWriteBytesTotal(), r.TimeWindow),
			}
		}
		if r.TsStats != nil {
			leaf := r.TsStats.Leaf
			apex := r.TsStats.Apex
			weight := r.TsStats.Weight

			if len(leaf) > maxLeafLength {
				maxLeafLength = len(leaf)
			}

			if len(apex) > maxApexLength {
				maxApexLength = len(apex)
			}

			if len(weight) > maxWeightLength {
				maxWeightLength = len(weight)
			}

			statTables[resourceKey][key].tsStats = &tsStats{
				apex:   apex,
				leaf:   leaf,
				weight: weight,
			}
		}
	}

	switch options.outputFormat {
	case tableOutput, wideOutput:
		if len(statTables) == 0 {
			fmt.Fprintln(os.Stderr, "No traffic found.")
			return
		}
		printStatTables(statTables, w, maxNameLength, maxNamespaceLength, maxLeafLength, maxApexLength, maxWeightLength, options)
	case jsonOutput:
		printStatJSON(statTables, w)
	}
}

func printStatTables(statTables map[string]map[string]*row, w *tabwriter.Writer, maxNameLength, maxNamespaceLength, maxLeafLength, maxApexLength, maxWeightLength int, options *statOptions) {
	usePrefix := false
	if len(statTables) > 1 {
		usePrefix = true
	}

	firstDisplayedStat := true // don't print a newline before the first stat
	for _, resourceType := range k8s.AllResources {
		if stats, ok := statTables[resourceType]; ok {
			if !firstDisplayedStat {
				fmt.Fprint(w, "\n")
			}
			firstDisplayedStat = false
			resourceTypeLabel := resourceType
			if !usePrefix {
				resourceTypeLabel = ""
			}
			printSingleStatTable(stats, resourceTypeLabel, resourceType, w, maxNameLength, maxNamespaceLength, maxLeafLength, maxApexLength, maxWeightLength, options)
		}
	}
}

func showTCPBytes(options *statOptions, resourceType string) bool {
	return (options.outputFormat == wideOutput || options.outputFormat == jsonOutput) &&
		showTCPConns(resourceType)
}

func showTCPConns(resourceType string) bool {
	return resourceType != k8s.Authority && resourceType != k8s.TrafficSplit
}

func printSingleStatTable(stats map[string]*row, resourceTypeLabel, resourceType string, w *tabwriter.Writer, maxNameLength, maxNamespaceLength, maxLeafLength, maxApexLength, maxWeightLength int, options *statOptions) {
	headers := make([]string, 0)
	nameTemplate := fmt.Sprintf("%%-%ds", maxNameLength)
	namespaceTemplate := fmt.Sprintf("%%-%ds", maxNamespaceLength)
	apexTemplate := fmt.Sprintf("%%-%ds", maxApexLength)
	leafTemplate := fmt.Sprintf("%%-%ds", maxLeafLength)
	weightTemplate := fmt.Sprintf("%%-%ds", maxWeightLength)

	if options.allNamespaces {
		headers = append(headers,
			fmt.Sprintf(namespaceTemplate, namespaceHeader))
	}

	headers = append(headers,
		fmt.Sprintf(nameTemplate, nameHeader))

	if resourceType == k8s.Pod {
		headers = append(headers, "STATUS")
	}

	if resourceType == k8s.TrafficSplit {
		headers = append(headers,
			fmt.Sprintf(apexTemplate, apexHeader),
			fmt.Sprintf(leafTemplate, leafHeader),
			fmt.Sprintf(weightTemplate, weightHeader))
	} else {
		headers = append(headers, "MESHED")
	}

	headers = append(headers, []string{
		"SUCCESS",
		"RPS",
		"LATENCY_P50",
		"LATENCY_P95",
		"LATENCY_P99",
	}...)

	if resourceType != k8s.TrafficSplit {
		headers = append(headers, "TCP_CONN")
	}

	if showTCPBytes(options, resourceType) {
		headers = append(headers, []string{
			"READ_BYTES/SEC",
			"WRITE_BYTES/SEC",
		}...)
	}

	headers[len(headers)-1] = headers[len(headers)-1] + "\t" // trailing \t is required to format last column

	fmt.Fprintln(w, strings.Join(headers, "\t"))

	sortedKeys := sortStatsKeys(stats)
	for _, key := range sortedKeys {
		namespace, name := namespaceName(resourceTypeLabel, key)
		values := make([]interface{}, 0)
		templateString := "%s\t%s\t%.2f%%\t%.1frps\t%dms\t%dms\t%dms\t"
		templateStringEmpty := "%s\t%s\t-\t-\t-\t-\t-\t-\t"
		if resourceType == k8s.Pod {
			templateString = "%s\t" + templateString
			templateStringEmpty = "%s\t" + templateStringEmpty
		}

		if resourceType == k8s.TrafficSplit {
			templateString = "%s\t%s\t%s\t%s\t%.2f%%\t%.1frps\t%dms\t%dms\t%dms\t"
			templateStringEmpty = "%s\t%s\t%s\t%s\t-\t-\t-\t-\t-\t"
		}

		if !showTCPConns(resourceType) {
			if resourceType == k8s.Authority {
				// always show TCP Connections as - for Authorities
				templateString = templateString + "-\t"
			}
		} else {
			templateString = templateString + "%d\t"
		}

		if showTCPBytes(options, resourceType) {
			templateString = templateString + "%.1fB/s\t%.1fB/s\t"
			templateStringEmpty = templateStringEmpty + "-\t-\t"
		}

		if options.allNamespaces {
			values = append(values,
				namespace+strings.Repeat(" ", maxNamespaceLength-len(namespace)))
			templateString = "%s\t" + templateString
			templateStringEmpty = "%s\t" + templateStringEmpty
		}

		templateString = templateString + "\n"
		templateStringEmpty = templateStringEmpty + "\n"

		padding := 0
		if maxNameLength > len(name) {
			padding = maxNameLength - len(name)
		}

		apexPadding := 0
		leafPadding := 0

		if stats[key].tsStats != nil {
			if maxApexLength > len(stats[key].tsStats.apex) {
				apexPadding = maxApexLength - len(stats[key].tsStats.apex)
			}
			if maxLeafLength > len(stats[key].tsStats.leaf) {
				leafPadding = maxLeafLength - len(stats[key].tsStats.leaf)
			}
		}

		values = append(values, name+strings.Repeat(" ", padding))
		if resourceType == k8s.Pod {
			values = append(values, stats[key].status)
		}

		if resourceType == k8s.TrafficSplit {
			values = append(values,
				stats[key].tsStats.apex+strings.Repeat(" ", apexPadding),
				stats[key].tsStats.leaf+strings.Repeat(" ", leafPadding),
				stats[key].tsStats.weight,
			)
		} else {
			values = append(values, []interface{}{
				stats[key].meshed,
			}...)
		}

		if stats[key].rowStats != nil {
			values = append(values, []interface{}{
				stats[key].successRate * 100,
				stats[key].requestRate,
				stats[key].latencyP50,
				stats[key].latencyP95,
				stats[key].latencyP99,
			}...)

			if showTCPConns(resourceType) {
				values = append(values, stats[key].tcpOpenConnections)
			}

			if showTCPBytes(options, resourceType) {
				values = append(values, []interface{}{
					stats[key].tcpReadBytes,
					stats[key].tcpWriteBytes,
				}...)
			}

			fmt.Fprintf(w, templateString, values...)
		} else {
			fmt.Fprintf(w, templateStringEmpty, values...)
		}
	}
}

func namespaceName(resourceType string, key string) (string, string) {
	parts := strings.Split(key, "/")
	namespace := parts[0]
	namePrefix := getNamePrefix(resourceType)
	name := namePrefix + parts[1]
	return namespace, name
}

// Using pointers where the value is NA and the corresponding json is null
type jsonStats struct {
	Namespace      string   `json:"namespace"`
	Kind           string   `json:"kind"`
	Name           string   `json:"name"`
	Meshed         string   `json:"meshed,omitempty"`
	Success        *float64 `json:"success"`
	Rps            *float64 `json:"rps"`
	LatencyMSp50   *uint64  `json:"latency_ms_p50"`
	LatencyMSp95   *uint64  `json:"latency_ms_p95"`
	LatencyMSp99   *uint64  `json:"latency_ms_p99"`
	TCPConnections *uint64  `json:"tcp_open_connections,omitempty"`
	TCPReadBytes   *float64 `json:"tcp_read_bytes_rate,omitempty"`
	TCPWriteBytes  *float64 `json:"tcp_write_bytes_rate,omitempty"`
	Apex           string   `json:"apex,omitempty"`
	Leaf           string   `json:"leaf,omitempty"`
	Weight         string   `json:"weight,omitempty"`
}

func printStatJSON(statTables map[string]map[string]*row, w *tabwriter.Writer) {
	// avoid nil initialization so that if there are not stats it gets marshalled as an empty array vs null
	entries := []*jsonStats{}
	for _, resourceType := range k8s.AllResources {
		if stats, ok := statTables[resourceType]; ok {
			sortedKeys := sortStatsKeys(stats)
			for _, key := range sortedKeys {
				namespace, name := namespaceName("", key)
				entry := &jsonStats{
					Namespace: namespace,
					Kind:      resourceType,
					Name:      name,
				}
				if resourceType != k8s.TrafficSplit {
					entry.Meshed = stats[key].meshed
				}
				if stats[key].rowStats != nil {
					entry.Success = &stats[key].successRate
					entry.Rps = &stats[key].requestRate
					entry.LatencyMSp50 = &stats[key].latencyP50
					entry.LatencyMSp95 = &stats[key].latencyP95
					entry.LatencyMSp99 = &stats[key].latencyP99

					if showTCPConns(resourceType) {
						entry.TCPConnections = &stats[key].tcpOpenConnections
						entry.TCPReadBytes = &stats[key].tcpReadBytes
						entry.TCPWriteBytes = &stats[key].tcpWriteBytes
					}
				}

				if stats[key].tsStats != nil {
					entry.Apex = stats[key].apex
					entry.Leaf = stats[key].leaf
					entry.Weight = stats[key].weight
				}
				entries = append(entries, entry)
			}
		}
	}
	b, err := json.MarshalIndent(entries, "", "  ")
	if err != nil {
		log.Error(err.Error())
		return
	}
	fmt.Fprintf(w, "%s\n", b)
}

func getNamePrefix(resourceType string) string {
	if resourceType == "" {
		return ""
	}

	canonicalType := k8s.ShortNameFromCanonicalResourceName(resourceType)
	return canonicalType + "/"
}

func buildStatSummaryRequests(resources []string, options *statOptions) ([]*pb.StatSummaryRequest, error) {
	targets, err := util.BuildResources(options.namespace, resources)
	if err != nil {
		return nil, err
	}

	var toRes, fromRes pb.Resource
	if options.toResource != "" {
		toRes, err = util.BuildResource(options.toNamespace, options.toResource)
		if err != nil {
			return nil, err
		}
	}
	if options.fromResource != "" {
		fromRes, err = util.BuildResource(options.fromNamespace, options.fromResource)
		if err != nil {
			return nil, err
		}
	}

	requests := make([]*pb.StatSummaryRequest, 0)
	for _, target := range targets {
		err = options.validate(target.Type)
		if err != nil {
			return nil, err
		}

		requestParams := util.StatsSummaryRequestParams{
			StatsBaseRequestParams: util.StatsBaseRequestParams{
				TimeWindow:    options.timeWindow,
				ResourceName:  target.Name,
				ResourceType:  target.Type,
				Namespace:     options.namespace,
				AllNamespaces: options.allNamespaces,
			},
			ToName:        toRes.Name,
			ToType:        toRes.Type,
			ToNamespace:   options.toNamespace,
			FromName:      fromRes.Name,
			FromType:      fromRes.Type,
			FromNamespace: options.fromNamespace,
			TCPStats:      true,
			LabelSelector: options.labelSelector,
		}

		req, err := util.BuildStatSummaryRequest(requestParams)
		if err != nil {
			return nil, err
		}
		requests = append(requests, req)
	}
	return requests, nil
}

func sortStatsKeys(stats map[string]*row) []string {
	var sortedKeys []string
	for key := range stats {
		sortedKeys = append(sortedKeys, key)
	}
	sort.Strings(sortedKeys)
	return sortedKeys
}

// validate performs all validation on the command-line options.
// It returns the first error encountered, or `nil` if the options are valid.
func (o *statOptions) validate(resourceType string) error {
	err := o.validateConflictingFlags()
	if err != nil {
		return err
	}

	if resourceType == k8s.Namespace {
		err := o.validateNamespaceFlags()
		if err != nil {
			return err
		}
	}

	return o.validateOutputFormat()
}

// validateConflictingFlags validates that the options do not contain mutually
// exclusive flags.
func (o *statOptions) validateConflictingFlags() error {
	if o.toResource != "" && o.fromResource != "" {
		return fmt.Errorf("--to and --from flags are mutually exclusive")
	}

	if o.toNamespace != "" && o.fromNamespace != "" {
		return fmt.Errorf("--to-namespace and --from-namespace flags are mutually exclusive")
	}

	if o.allNamespaces && o.namespace != "default" {
		return fmt.Errorf("--all-namespaces and --namespace flags are mutually exclusive")
	}

	return nil
}

// validateNamespaceFlags performs additional validation for options when the target
// resource type is a namespace.
func (o *statOptions) validateNamespaceFlags() error {
	if o.toNamespace != "" {
		return fmt.Errorf("--to-namespace flag is incompatible with namespace resource type")
	}

	if o.fromNamespace != "" {
		return fmt.Errorf("--from-namespace flag is incompatible with namespace resource type")
	}

	// Note: technically, this allows you to say `stat ns --namespace default`, but that
	// seems like an edge case.
	if o.namespace != "default" {
		return fmt.Errorf("--namespace flag is incompatible with namespace resource type")
	}

	return nil
}

// get byte rate calculates the read/write byte rate
func getByteRate(bytes uint64, timeWindow string) float64 {
	windowLength, err := time.ParseDuration(timeWindow)
	if err != nil {
		log.Error(err.Error())
		return 0.0
	}
	return float64(bytes) / windowLength.Seconds()
}