Function Stats

pkg/cmd/container/stats.go:85–341

Stats displays a live stream of container(s) resource usage statistics.

(ctx context.Context, client *containerd.Client, containerIDs []string, options types.ContainerStatsOptions)

// Stats displays a live stream of container(s) resource usage statistics.
func Stats(ctx context.Context, client *containerd.Client, containerIDs []string, options types.ContainerStatsOptions) error {
	// NOTE: rootless container does not rely on cgroupv1.
	// more details about possible ways to resolve this concern: #223
	if rootlessutil.IsRootless() && infoutil.CgroupsVersion() == "1" {
		return errors.New("stats requires cgroup v2 for rootless containers, see https://rootlesscontaine.rs/getting-started/common/cgroup2/")
	}

	showAll := len(containerIDs) == 0
	closeChan := make(chan error)

	var err error
	w := options.Stdout
	var tmpl *template.Template
	switch options.Format {
	case "", "table":
		w = tabwriter.NewWriter(options.Stdout, 10, 1, 3, ' ', 0)
	case "raw":
		return errors.New("unsupported format: \"raw\"")
	default:
		tmpl, err = formatter.ParseTemplate(options.Format)
		if err != nil {
			return err
		}
	}

	// waitFirst is a WaitGroup to wait first stat data's reach for each container
	waitFirst := &sync.WaitGroup{}
	cStats := stats{}

	monitorContainerEvents := func(started chan<- struct{}, c chan *events.Envelope, closeEventChan chan struct{}) {
		eventsClient := client.EventService()
		eventsCh, errCh := eventsClient.Subscribe(ctx)

		// Whether we successfully subscribed to eventsCh or not, we can now
		// unblock the main goroutine.
		close(started)

		for {
			select {
			case <-closeEventChan:
				// c is closed, so we can stop monitoring events
				return
			case event := <-eventsCh:
				c <- event
			case err = <-errCh:
				closeChan <- err
				return
			}
		}
	}

	// getContainerList get all existing containers (only used when calling `nerdctl stats` without arguments).
	getContainerList := func() {
		containers, err := client.Containers(ctx)
		if err != nil {
			closeChan <- err
		}