Update opts.MemBytes to disable default, and move docker run/create/build to use opts.MemBytes

This fix made several updates:
1. Update opts.MemBytes so that default value will not show up.
   The reason is that in case a default value is decided by daemon,
   instead of client, we actually want to not show default value.
2. Move `docker run/create/build` to use opts.MemBytes for `--shm-size`
   This is to bring consistency between daemon and docker run
3. docs updates.

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

command/container/opts.go

@@ -100,7 +100,7 @@ type containerOptions struct {
 	stopSignal         string
 	stopTimeout        int
 	isolation          string
-	shmSize            string
+	shmSize            opts.MemBytes
 	noHealthcheck      bool
 	healthCmd          string
 	healthInterval     time.Duration
@@ -259,7 +259,7 @@ func addFlags(flags *pflag.FlagSet) *containerOptions {
 	flags.StringVar(&copts.ipcMode, "ipc", "", "IPC namespace to use")
 	flags.StringVar(&copts.isolation, "isolation", "", "Container isolation technology")
 	flags.StringVar(&copts.pidMode, "pid", "", "PID namespace to use")
-	flags.StringVar(&copts.shmSize, "shm-size", "", "Size of /dev/shm, default value is 64MB")
+	flags.Var(&copts.shmSize, "shm-size", "Size of /dev/shm")
 	flags.StringVar(&copts.utsMode, "uts", "", "UTS namespace to use")
 	flags.StringVar(&copts.runtime, "runtime", "", "Runtime to use for this container")
 
@@ -336,14 +336,6 @@ func parse(flags *pflag.FlagSet, copts *containerOptions) (*container.Config, *c
 		return nil, nil, nil, fmt.Errorf("invalid value: %d. Valid memory swappiness range is 0-100", swappiness)
 	}
 
-	var shmSize int64
-	if copts.shmSize != "" {
-		shmSize, err = units.RAMInBytes(copts.shmSize)
-		if err != nil {
-			return nil, nil, nil, err
-		}
-	}
-
 	// TODO FIXME units.RAMInBytes should have a uint64 version
 	var maxIOBandwidth int64
 	if copts.ioMaxBandwidth != "" {
@@ -615,7 +607,7 @@ func parse(flags *pflag.FlagSet, copts *containerOptions) (*container.Config, *c
 		LogConfig:      container.LogConfig{Type: copts.loggingDriver, Config: loggingOpts},
 		VolumeDriver:   copts.volumeDriver,
 		Isolation:      container.Isolation(copts.isolation),
-		ShmSize:        shmSize,
+		ShmSize:        copts.shmSize.Value(),
 		Resources:      resources,
 		Tmpfs:          tmpfs,
 		Sysctls:        copts.sysctls.GetAll(),

command/container/opts_test.go

@@ -411,8 +411,9 @@ func TestParseModes(t *testing.T) {
 		t.Fatalf("Expected a valid UTSMode, got %v", hostconfig.UTSMode)
 	}
 	// shm-size ko
-	if _, _, _, err = parseRun([]string{"--shm-size=a128m", "img", "cmd"}); err == nil || err.Error() != "invalid size: 'a128m'" {
-		t.Fatalf("Expected an error with message 'invalid size: a128m', got %v", err)
+	expectedErr := `invalid argument "a128m" for --shm-size=a128m: invalid size: 'a128m'`
+	if _, _, _, err = parseRun([]string{"--shm-size=a128m", "img", "cmd"}); err == nil || err.Error() != expectedErr {
+		t.Fatalf("Expected an error with message '%v', got %v", expectedErr, err)
 	}
 	// shm-size ok
 	_, hostconfig, _, err = parseRun([]string{"--shm-size=128m", "img", "cmd"})