// runStats displays a live stream of resource usage statistics for one or more containers.
// This shows real-time information on CPU usage, memory usage, and network I/O.
func runStats(dockerCli *command.DockerCli, opts *statsOptions) error {
showAll := len(opts.containers) == 0
closeChan := make(chan error)
ctx := context.Background()
// monitorContainerEvents watches for container creation and removal (only
// used when calling `docker stats` without arguments).
monitorContainerEvents := func(started chan<- struct{}, c chan events.Message) {
f := filters.NewArgs()
f.Add("type", "container")
options := types.EventsOptions{
Filters: f,
}
resBody, err := dockerCli.Client().Events(ctx, options)
// Whether we successfully subscribed to events or not, we can now
// unblock the main goroutine.
close(started)
if err != nil {
closeChan <- err
return
}
defer resBody.Close()
system.DecodeEvents(resBody, func(event events.Message, err error) error {
if err != nil {
closeChan <- err
return nil
}
c <- event
return nil
})
}
// waitFirst is a WaitGroup to wait first stat data's reach for each container
waitFirst := &sync.WaitGroup{}
cStats := stats{}
// getContainerList simulates creation event for all previously existing
// containers (only used when calling `docker stats` without arguments).
getContainerList := func() {
options := types.ContainerListOptions{
All: opts.all,
}
cs, err := dockerCli.Client().ContainerList(ctx, options)
if err != nil {
closeChan <- err
}
for _, container := range cs {
s := &containerStats{Name: container.ID[:12]}
if cStats.add(s) {
waitFirst.Add(1)
go s.Collect(ctx, dockerCli.Client(), !opts.noStream, waitFirst)
}
}
}
if showAll {
// If no names were specified, start a long running goroutine which
// monitors container events. We make sure we're subscribed before
// retrieving the list of running containers to avoid a race where we
// would "miss" a creation.
started := make(chan struct{})
eh := system.InitEventHandler()
eh.Handle("create", func(e events.Message) {
if opts.all {
s := &containerStats{Name: e.ID[:12]}
if cStats.add(s) {
waitFirst.Add(1)
go s.Collect(ctx, dockerCli.Client(), !opts.noStream, waitFirst)
}
}
})
eh.Handle("start", func(e events.Message) {
s := &containerStats{Name: e.ID[:12]}
if cStats.add(s) {
waitFirst.Add(1)
go s.Collect(ctx, dockerCli.Client(), !opts.noStream, waitFirst)
}
})
eh.Handle("die", func(e events.Message) {
if !opts.all {
cStats.remove(e.ID[:12])
}
})
eventChan := make(chan events.Message)
go eh.Watch(eventChan)
go monitorContainerEvents(started, eventChan)
defer close(eventChan)
<-started
// Start a short-lived goroutine to retrieve the initial list of
// containers.
getContainerList()
} else {
// Artificially send creation events for the containers we were asked to
// monitor (same code path than we use when monitoring all containers).
for _, name := range opts.containers {
s := &containerStats{Name: name}
if cStats.add(s) {
waitFirst.Add(1)
go s.Collect(ctx, dockerCli.Client(), !opts.noStream, waitFirst)
}
}
// We don't expect any asynchronous errors: closeChan can be closed.
close(closeChan)
// Do a quick pause to detect any error with the provided list of
// container names.
time.Sleep(1500 * time.Millisecond)
var errs []string
cStats.mu.Lock()
for _, c := range cStats.cs {
c.mu.Lock()
if c.err != nil {
errs = append(errs, fmt.Sprintf("%s: %v", c.Name, c.err))
}
c.mu.Unlock()
}
cStats.mu.Unlock()
if len(errs) > 0 {
return fmt.Errorf("%s", strings.Join(errs, ", "))
}
}
// before print to screen, make sure each container get at least one valid stat data
waitFirst.Wait()
w := tabwriter.NewWriter(dockerCli.Out(), 20, 1, 3, ' ', 0)
printHeader := func() {
if !opts.noStream {
fmt.Fprint(dockerCli.Out(), "\033[2J")
fmt.Fprint(dockerCli.Out(), "\033[H")
}
io.WriteString(w, "CONTAINER\tCPU %\tMEM USAGE / LIMIT\tMEM %\tNET I/O\tBLOCK I/O\tPIDS\n")
}
for range time.Tick(500 * time.Millisecond) {
printHeader()
toRemove := []string{}
cStats.mu.Lock()
for _, s := range cStats.cs {
if err := s.Display(w); err != nil && !opts.noStream {
logrus.Debugf("stats: got error for %s: %v", s.Name, err)
if err == io.EOF {
toRemove = append(toRemove, s.Name)
}
}
}
cStats.mu.Unlock()
for _, name := range toRemove {
cStats.remove(name)
}
if len(cStats.cs) == 0 && !showAll {
return nil
}
w.Flush()
if opts.noStream {
break
}
select {
case err, ok := <-closeChan:
if ok {
if err != nil {
// this is suppressing "unexpected EOF" in the cli when the
// daemon restarts so it shutdowns cleanly
if err == io.ErrUnexpectedEOF {
return nil
}
return err
}
}
default:
// just skip
}
}
return nil
}
func waitExitOrRemoved(dockerCli *command.DockerCli, ctx context.Context, containerID string, waitRemove bool) (chan int, error) {
if len(containerID) == 0 {
// containerID can never be empty
panic("Internal Error: waitExitOrRemoved needs a containerID as parameter")
}
statusChan := make(chan int)
exitCode := 125
eventProcessor := func(e events.Message, err error) error {
if err != nil {
statusChan <- exitCode
return fmt.Errorf("failed to decode event: %v", err)
}
stopProcessing := false
switch e.Status {
case "die":
if v, ok := e.Actor.Attributes["exitCode"]; ok {
code, cerr := strconv.Atoi(v)
if cerr != nil {
logrus.Errorf("failed to convert exitcode '%q' to int: %v", v, cerr)
} else {
exitCode = code
}
}
if !waitRemove {
stopProcessing = true
}
case "detach":
exitCode = 0
stopProcessing = true
case "destroy":
stopProcessing = true
}
if stopProcessing {
statusChan <- exitCode
// stop the loop processing
return fmt.Errorf("done")
}
return nil
}
// Get events via Events API
f := filters.NewArgs()
f.Add("type", "container")
f.Add("container", containerID)
options := types.EventsOptions{
Filters: f,
}
resBody, err := dockerCli.Client().Events(ctx, options)
if err != nil {
return nil, fmt.Errorf("can't get events from daemon: %v", err)
}
go system.DecodeEvents(resBody, eventProcessor)
return statusChan, nil
}