@@ -118,7 +118,10 @@ func (d *Daemon) ContainerExecCreate(job *engine.Job) engine.Status {

 		return job.Error(err)

 	}

-	config := runconfig.ExecConfigFromJob(job)

+	config, err := runconfig.ExecConfigFromJob(job)

+	if err != nil {

+		return job.Error(err)

+	}

 	entrypoint, args := d.getEntrypointAndArgs(nil, config.Cmd)

@@ -23,7 +23,7 @@ func TestContainerApiGetAll(t *testing.T) {

 		t.Fatalf("Error on container creation: %v, output: %q", err, out)

 	}

-	body, err := sockRequest("GET", "/containers/json?all=1")

+	body, err := sockRequest("GET", "/containers/json?all=1", nil)

 	if err != nil {

 		t.Fatalf("GET all containers sockRequest failed: %v", err)

 	}

@@ -56,7 +56,7 @@ func TestContainerApiGetExport(t *testing.T) {

 		t.Fatalf("Error on container creation: %v, output: %q", err, out)

 	}

-	body, err := sockRequest("GET", "/containers/"+name+"/export")

+	body, err := sockRequest("GET", "/containers/"+name+"/export", nil)

 	if err != nil {

 		t.Fatalf("GET containers/export sockRequest failed: %v", err)

 	}

@@ -92,7 +92,7 @@ func TestContainerApiGetChanges(t *testing.T) {

 		t.Fatalf("Error on container creation: %v, output: %q", err, out)

 	}

-	body, err := sockRequest("GET", "/containers/"+name+"/changes")

+	body, err := sockRequest("GET", "/containers/"+name+"/changes", nil)

 	if err != nil {

 		t.Fatalf("GET containers/changes sockRequest failed: %v", err)

 	}

new file mode 100644

@@ -0,0 +1,25 @@

+package main

+

+import (

+	"bytes"

+	"fmt"

+	"os/exec"

+	"testing"

+)

+

+// Regression test for #9414

+func TestExecApiCreateNoCmd(t *testing.T) {

+	defer deleteAllContainers()

+	name := "exec_test"

+	runCmd := exec.Command(dockerBinary, "run", "-d", "-t", "--name", name, "busybox", "/bin/sh")

+	if out, _, err := runCommandWithOutput(runCmd); err != nil {

+		t.Fatal(out, err)

+	}

+

+	body, err := sockRequest("POST", fmt.Sprintf("/containers/%s/exec", name), map[string]interface{}{"Cmd": nil})

+	if err == nil || !bytes.Contains(body, []byte("No exec command specified")) {

+		t.Fatalf("Expected error when creating exec command with no Cmd specified: %q", err)

+	}

+

+	logDone("exec create API - returns error when missing Cmd")

+}

@@ -24,7 +24,7 @@ func TestInspectApiContainerResponse(t *testing.T) {

 		if testVersion != "latest" {

 			endpoint = "/" + testVersion + endpoint

 		}

-		body, err := sockRequest("GET", endpoint)

+		body, err := sockRequest("GET", endpoint, nil)

 		if err != nil {

 			t.Fatalf("sockRequest failed for %s version: %v", testVersion, err)

 		}

@@ -16,7 +16,7 @@ func TestResizeApiResponse(t *testing.T) {

 	cleanedContainerID := stripTrailingCharacters(out)

 	endpoint := "/containers/" + cleanedContainerID + "/resize?h=40&w=40"

-	_, err = sockRequest("POST", endpoint)

+	_, err = sockRequest("POST", endpoint, nil)

 	if err != nil {

 		t.Fatalf("resize Request failed %v", err)

 	}

@@ -41,7 +41,7 @@ func TestResizeApiResponseWhenContainerNotStarted(t *testing.T) {

 	}

 	endpoint := "/containers/" + cleanedContainerID + "/resize?h=40&w=40"

-	body, err := sockRequest("POST", endpoint)

+	body, err := sockRequest("POST", endpoint, nil)

 	if err == nil {

 		t.Fatalf("resize should fail when container is not started")

 	}

@@ -1,6 +1,8 @@

 package main

 import (

+	"bytes"

+	"encoding/json"

 	"errors"

 	"fmt"

 	"io"

@@ -249,7 +251,7 @@ func (d *Daemon) Cmd(name string, arg ...string) (string, error) {

 	return string(b), err

 }

-func sockRequest(method, endpoint string) ([]byte, error) {

+func sockRequest(method, endpoint string, data interface{}) ([]byte, error) {

 	// FIX: the path to sock should not be hardcoded

 	sock := filepath.Join("/", "var", "run", "docker.sock")

 	c, err := net.DialTimeout("unix", sock, time.Duration(10*time.Second))

@@ -260,7 +262,12 @@ func sockRequest(method, endpoint string) ([]byte, error) {

 	client := httputil.NewClientConn(c, nil)

 	defer client.Close()

-	req, err := http.NewRequest(method, endpoint, nil)

+	jsonData := bytes.NewBuffer(nil)

+	if err := json.NewEncoder(jsonData).Encode(data); err != nil {

+		return nil, err

+	}

+

+	req, err := http.NewRequest(method, endpoint, jsonData)

 	req.Header.Set("Content-Type", "application/json")

 	if err != nil {

 		return nil, fmt.Errorf("could not create new request: %v", err)

@@ -1,6 +1,8 @@

 package runconfig

 import (

+	"fmt"

+

 	"github.com/docker/docker/engine"

 	flag "github.com/docker/docker/pkg/mflag"

 )

@@ -17,7 +19,7 @@ type ExecConfig struct {

 	Cmd          []string

 }

-func ExecConfigFromJob(job *engine.Job) *ExecConfig {

+func ExecConfigFromJob(job *engine.Job) (*ExecConfig, error) {

 	execConfig := &ExecConfig{

 		// TODO(vishh): Expose 'User' once it is supported.

 		//User:         job.Getenv("User"),

@@ -28,11 +30,14 @@ func ExecConfigFromJob(job *engine.Job) *ExecConfig {

 		AttachStderr: job.GetenvBool("AttachStderr"),

 		AttachStdout: job.GetenvBool("AttachStdout"),

 	}

-	if cmd := job.GetenvList("Cmd"); cmd != nil {

-		execConfig.Cmd = cmd

+	cmd := job.GetenvList("Cmd")

+	if len(cmd) == 0 {

+		return nil, fmt.Errorf("No exec command specified")

 	}

-	return execConfig

+	execConfig.Cmd = cmd

+

+	return execConfig, nil

 }

 func ParseExec(cmd *flag.FlagSet, args []string) (*ExecConfig, error) {

@@ -47,10 +52,11 @@ func ParseExec(cmd *flag.FlagSet, args []string) (*ExecConfig, error) {

 		return nil, err

 	}

 	parsedArgs := cmd.Args()

-	if len(parsedArgs) > 1 {

-		container = cmd.Arg(0)

-		execCmd = parsedArgs[1:]

+	if len(parsedArgs) < 2 {

+		return nil, fmt.Errorf("not enough arguments to create exec command")

 	}

+	container = cmd.Arg(0)

+	execCmd = parsedArgs[1:]

 	execConfig := &ExecConfig{

 		// TODO(vishh): Expose '-u' flag once it is supported.