Merge pull request #10766 from cpuguy83/stats_pull_once

Allow pulling stats once and disconnecting.

api/client/stats.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"net/url"
 	"sort"
 	"strings"
 	"sync"
@@ -27,8 +28,14 @@ type containerStats struct {
 	err              error
 }
 
-func (s *containerStats) Collect(cli *DockerCli) {
-	stream, _, err := cli.call("GET", "/containers/"+s.Name+"/stats", nil, nil)
+func (s *containerStats) Collect(cli *DockerCli, streamStats bool) {
+	v := url.Values{}
+	if streamStats {
+		v.Set("stream", "1")
+	} else {
+		v.Set("stream", "0")
+	}
+	stream, _, err := cli.call("GET", "/containers/"+s.Name+"/stats?"+v.Encode(), nil, nil)
 	if err != nil {
 		s.err = err
 		return
@@ -67,6 +74,9 @@ func (s *containerStats) Collect(cli *DockerCli) {
 			previousCPU = v.CpuStats.CpuUsage.TotalUsage
 			previousSystem = v.CpuStats.SystemUsage
 			u <- nil
+			if !streamStats {
+				return
+			}
 		}
 	}()
 	for {
@@ -87,6 +97,9 @@ func (s *containerStats) Collect(cli *DockerCli) {
 				return
 			}
 		}
+		if !streamStats {
+			return
+		}
 	}
 }
 
@@ -112,6 +125,7 @@ func (s *containerStats) Display(w io.Writer) error {
 // Usage: docker stats CONTAINER [CONTAINER...]
 func (cli *DockerCli) CmdStats(args ...string) error {
 	cmd := cli.Subcmd("stats", "CONTAINER [CONTAINER...]", "Display a live stream of one or more containers' resource usage statistics", true)
+	noStream := cmd.Bool([]string{"-no-stream"}, false, "Disable streaming stats and only pull the first result")
 	cmd.Require(flag.Min, 1)
 	cmd.ParseFlags(args, true)
 
@@ -122,14 +136,16 @@ func (cli *DockerCli) CmdStats(args ...string) error {
 		w      = tabwriter.NewWriter(cli.out, 20, 1, 3, ' ', 0)
 	)
 	printHeader := func() {
-		io.WriteString(cli.out, "\033[2J")
-		io.WriteString(cli.out, "\033[H")
+		if !*noStream {
+			fmt.Fprint(cli.out, "\033[2J")
+			fmt.Fprint(cli.out, "\033[H")
+		}
 		io.WriteString(w, "CONTAINER\tCPU %\tMEM USAGE/LIMIT\tMEM %\tNET I/O\n")
 	}
 	for _, n := range names {
 		s := &containerStats{Name: n}
 		cStats = append(cStats, s)
-		go s.Collect(cli)
+		go s.Collect(cli, !*noStream)
 	}
 	// do a quick pause so that any failed connections for containers that do not exist are able to be
 	// evicted before we display the initial or default values.
@@ -149,7 +165,7 @@ func (cli *DockerCli) CmdStats(args ...string) error {
 		printHeader()
 		toRemove := []int{}
 		for i, s := range cStats {
-			if err := s.Display(w); err != nil {
+			if err := s.Display(w); err != nil && !*noStream {
 				toRemove = append(toRemove, i)
 			}
 		}
@@ -161,6 +177,9 @@ func (cli *DockerCli) CmdStats(args ...string) error {
 			return nil
 		}
 		w.Flush()
+		if *noStream {
+			break
+		}
 	}
 	return nil
 }