github.com/rsampaio/docker@v0.7.2-0.20150827203920-fdc73cc3fc31/integration-cli/docker_cli_exec_test.go (about)

     1  // +build !test_no_exec
     2  
     3  package main
     4  
     5  import (
     6  	"bufio"
     7  	"fmt"
     8  	"net/http"
     9  	"os"
    10  	"os/exec"
    11  	"path/filepath"
    12  	"reflect"
    13  	"sort"
    14  	"strings"
    15  	"sync"
    16  	"time"
    17  
    18  	"github.com/go-check/check"
    19  )
    20  
    21  func (s *DockerSuite) TestExec(c *check.C) {
    22  	dockerCmd(c, "run", "-d", "--name", "testing", "busybox", "sh", "-c", "echo test > /tmp/file && top")
    23  
    24  	out, _ := dockerCmd(c, "exec", "testing", "cat", "/tmp/file")
    25  	out = strings.Trim(out, "\r\n")
    26  	if out != "test" {
    27  		c.Errorf("container exec should've printed test but printed %q", out)
    28  	}
    29  
    30  }
    31  
    32  func (s *DockerSuite) TestExecInteractive(c *check.C) {
    33  	dockerCmd(c, "run", "-d", "--name", "testing", "busybox", "sh", "-c", "echo test > /tmp/file && top")
    34  
    35  	execCmd := exec.Command(dockerBinary, "exec", "-i", "testing", "sh")
    36  	stdin, err := execCmd.StdinPipe()
    37  	if err != nil {
    38  		c.Fatal(err)
    39  	}
    40  	stdout, err := execCmd.StdoutPipe()
    41  	if err != nil {
    42  		c.Fatal(err)
    43  	}
    44  
    45  	if err := execCmd.Start(); err != nil {
    46  		c.Fatal(err)
    47  	}
    48  	if _, err := stdin.Write([]byte("cat /tmp/file\n")); err != nil {
    49  		c.Fatal(err)
    50  	}
    51  
    52  	r := bufio.NewReader(stdout)
    53  	line, err := r.ReadString('\n')
    54  	if err != nil {
    55  		c.Fatal(err)
    56  	}
    57  	line = strings.TrimSpace(line)
    58  	if line != "test" {
    59  		c.Fatalf("Output should be 'test', got '%q'", line)
    60  	}
    61  	if err := stdin.Close(); err != nil {
    62  		c.Fatal(err)
    63  	}
    64  	errChan := make(chan error)
    65  	go func() {
    66  		errChan <- execCmd.Wait()
    67  		close(errChan)
    68  	}()
    69  	select {
    70  	case err := <-errChan:
    71  		c.Assert(err, check.IsNil)
    72  	case <-time.After(1 * time.Second):
    73  		c.Fatal("docker exec failed to exit on stdin close")
    74  	}
    75  
    76  }
    77  
    78  func (s *DockerSuite) TestExecAfterContainerRestart(c *check.C) {
    79  	out, _ := dockerCmd(c, "run", "-d", "busybox", "top")
    80  	cleanedContainerID := strings.TrimSpace(out)
    81  	dockerCmd(c, "restart", cleanedContainerID)
    82  
    83  	out, _ = dockerCmd(c, "exec", cleanedContainerID, "echo", "hello")
    84  	outStr := strings.TrimSpace(out)
    85  	if outStr != "hello" {
    86  		c.Errorf("container should've printed hello, instead printed %q", outStr)
    87  	}
    88  }
    89  
    90  func (s *DockerDaemonSuite) TestExecAfterDaemonRestart(c *check.C) {
    91  	testRequires(c, SameHostDaemon)
    92  
    93  	if err := s.d.StartWithBusybox(); err != nil {
    94  		c.Fatalf("Could not start daemon with busybox: %v", err)
    95  	}
    96  
    97  	if out, err := s.d.Cmd("run", "-d", "--name", "top", "-p", "80", "busybox:latest", "top"); err != nil {
    98  		c.Fatalf("Could not run top: err=%v\n%s", err, out)
    99  	}
   100  
   101  	if err := s.d.Restart(); err != nil {
   102  		c.Fatalf("Could not restart daemon: %v", err)
   103  	}
   104  
   105  	if out, err := s.d.Cmd("start", "top"); err != nil {
   106  		c.Fatalf("Could not start top after daemon restart: err=%v\n%s", err, out)
   107  	}
   108  
   109  	out, err := s.d.Cmd("exec", "top", "echo", "hello")
   110  	if err != nil {
   111  		c.Fatalf("Could not exec on container top: err=%v\n%s", err, out)
   112  	}
   113  
   114  	outStr := strings.TrimSpace(string(out))
   115  	if outStr != "hello" {
   116  		c.Errorf("container should've printed hello, instead printed %q", outStr)
   117  	}
   118  }
   119  
   120  // Regression test for #9155, #9044
   121  func (s *DockerSuite) TestExecEnv(c *check.C) {
   122  	dockerCmd(c, "run", "-e", "LALA=value1", "-e", "LALA=value2",
   123  		"-d", "--name", "testing", "busybox", "top")
   124  
   125  	out, _ := dockerCmd(c, "exec", "testing", "env")
   126  	if strings.Contains(out, "LALA=value1") ||
   127  		!strings.Contains(out, "LALA=value2") ||
   128  		!strings.Contains(out, "HOME=/root") {
   129  		c.Errorf("exec env(%q), expect %q, %q", out, "LALA=value2", "HOME=/root")
   130  	}
   131  }
   132  
   133  func (s *DockerSuite) TestExecExitStatus(c *check.C) {
   134  	dockerCmd(c, "run", "-d", "--name", "top", "busybox", "top")
   135  
   136  	// Test normal (non-detached) case first
   137  	cmd := exec.Command(dockerBinary, "exec", "top", "sh", "-c", "exit 23")
   138  	ec, _ := runCommand(cmd)
   139  	if ec != 23 {
   140  		c.Fatalf("Should have had an ExitCode of 23, not: %d", ec)
   141  	}
   142  }
   143  
   144  func (s *DockerSuite) TestExecPausedContainer(c *check.C) {
   145  	defer unpauseAllContainers()
   146  
   147  	out, _ := dockerCmd(c, "run", "-d", "--name", "testing", "busybox", "top")
   148  	ContainerID := strings.TrimSpace(out)
   149  
   150  	dockerCmd(c, "pause", "testing")
   151  	out, _, err := dockerCmdWithError("exec", "-i", "-t", ContainerID, "echo", "hello")
   152  	if err == nil {
   153  		c.Fatal("container should fail to exec new command if it is paused")
   154  	}
   155  
   156  	expected := ContainerID + " is paused, unpause the container before exec"
   157  	if !strings.Contains(out, expected) {
   158  		c.Fatal("container should not exec new command if it is paused")
   159  	}
   160  }
   161  
   162  // regression test for #9476
   163  func (s *DockerSuite) TestExecTtyCloseStdin(c *check.C) {
   164  	dockerCmd(c, "run", "-d", "-it", "--name", "exec_tty_stdin", "busybox")
   165  
   166  	cmd := exec.Command(dockerBinary, "exec", "-i", "exec_tty_stdin", "cat")
   167  	stdinRw, err := cmd.StdinPipe()
   168  	if err != nil {
   169  		c.Fatal(err)
   170  	}
   171  
   172  	stdinRw.Write([]byte("test"))
   173  	stdinRw.Close()
   174  
   175  	if out, _, err := runCommandWithOutput(cmd); err != nil {
   176  		c.Fatal(out, err)
   177  	}
   178  
   179  	out, _ := dockerCmd(c, "top", "exec_tty_stdin")
   180  	outArr := strings.Split(out, "\n")
   181  	if len(outArr) > 3 || strings.Contains(out, "nsenter-exec") {
   182  		c.Fatalf("exec process left running\n\t %s", out)
   183  	}
   184  }
   185  
   186  func (s *DockerSuite) TestExecTtyWithoutStdin(c *check.C) {
   187  	out, _ := dockerCmd(c, "run", "-d", "-ti", "busybox")
   188  	id := strings.TrimSpace(out)
   189  	c.Assert(waitRun(id), check.IsNil)
   190  
   191  	errChan := make(chan error)
   192  	go func() {
   193  		defer close(errChan)
   194  
   195  		cmd := exec.Command(dockerBinary, "exec", "-ti", id, "true")
   196  		if _, err := cmd.StdinPipe(); err != nil {
   197  			errChan <- err
   198  			return
   199  		}
   200  
   201  		expected := "cannot enable tty mode"
   202  		if out, _, err := runCommandWithOutput(cmd); err == nil {
   203  			errChan <- fmt.Errorf("exec should have failed")
   204  			return
   205  		} else if !strings.Contains(out, expected) {
   206  			errChan <- fmt.Errorf("exec failed with error %q: expected %q", out, expected)
   207  			return
   208  		}
   209  	}()
   210  
   211  	select {
   212  	case err := <-errChan:
   213  		c.Assert(err, check.IsNil)
   214  	case <-time.After(3 * time.Second):
   215  		c.Fatal("exec is running but should have failed")
   216  	}
   217  }
   218  
   219  func (s *DockerSuite) TestExecParseError(c *check.C) {
   220  	dockerCmd(c, "run", "-d", "--name", "top", "busybox", "top")
   221  
   222  	// Test normal (non-detached) case first
   223  	cmd := exec.Command(dockerBinary, "exec", "top")
   224  	if _, stderr, code, err := runCommandWithStdoutStderr(cmd); err == nil || !strings.Contains(stderr, "See '"+dockerBinary+" exec --help'") || code == 0 {
   225  		c.Fatalf("Should have thrown error & point to help: %s", stderr)
   226  	}
   227  }
   228  
   229  func (s *DockerSuite) TestExecStopNotHanging(c *check.C) {
   230  	dockerCmd(c, "run", "-d", "--name", "testing", "busybox", "top")
   231  
   232  	if err := exec.Command(dockerBinary, "exec", "testing", "top").Start(); err != nil {
   233  		c.Fatal(err)
   234  	}
   235  
   236  	type dstop struct {
   237  		out []byte
   238  		err error
   239  	}
   240  
   241  	ch := make(chan dstop)
   242  	go func() {
   243  		out, err := exec.Command(dockerBinary, "stop", "testing").CombinedOutput()
   244  		ch <- dstop{out, err}
   245  		close(ch)
   246  	}()
   247  	select {
   248  	case <-time.After(3 * time.Second):
   249  		c.Fatal("Container stop timed out")
   250  	case s := <-ch:
   251  		c.Assert(s.err, check.IsNil)
   252  	}
   253  }
   254  
   255  func (s *DockerSuite) TestExecCgroup(c *check.C) {
   256  	dockerCmd(c, "run", "-d", "--name", "testing", "busybox", "top")
   257  
   258  	out, _ := dockerCmd(c, "exec", "testing", "cat", "/proc/1/cgroup")
   259  	containerCgroups := sort.StringSlice(strings.Split(out, "\n"))
   260  
   261  	var wg sync.WaitGroup
   262  	var mu sync.Mutex
   263  	execCgroups := []sort.StringSlice{}
   264  	errChan := make(chan error)
   265  	// exec a few times concurrently to get consistent failure
   266  	for i := 0; i < 5; i++ {
   267  		wg.Add(1)
   268  		go func() {
   269  			out, _, err := dockerCmdWithError("exec", "testing", "cat", "/proc/self/cgroup")
   270  			if err != nil {
   271  				errChan <- err
   272  				return
   273  			}
   274  			cg := sort.StringSlice(strings.Split(out, "\n"))
   275  
   276  			mu.Lock()
   277  			execCgroups = append(execCgroups, cg)
   278  			mu.Unlock()
   279  			wg.Done()
   280  		}()
   281  	}
   282  	wg.Wait()
   283  	close(errChan)
   284  
   285  	for err := range errChan {
   286  		c.Assert(err, check.IsNil)
   287  	}
   288  
   289  	for _, cg := range execCgroups {
   290  		if !reflect.DeepEqual(cg, containerCgroups) {
   291  			fmt.Println("exec cgroups:")
   292  			for _, name := range cg {
   293  				fmt.Printf(" %s\n", name)
   294  			}
   295  
   296  			fmt.Println("container cgroups:")
   297  			for _, name := range containerCgroups {
   298  				fmt.Printf(" %s\n", name)
   299  			}
   300  			c.Fatal("cgroups mismatched")
   301  		}
   302  	}
   303  }
   304  
   305  func (s *DockerSuite) TestInspectExecID(c *check.C) {
   306  	out, _ := dockerCmd(c, "run", "-d", "busybox", "top")
   307  	id := strings.TrimSuffix(out, "\n")
   308  
   309  	out, err := inspectField(id, "ExecIDs")
   310  	if err != nil {
   311  		c.Fatalf("failed to inspect container: %s, %v", out, err)
   312  	}
   313  	if out != "[]" {
   314  		c.Fatalf("ExecIDs should be empty, got: %s", out)
   315  	}
   316  
   317  	// Start an exec, have it block waiting so we can do some checking
   318  	cmd := exec.Command(dockerBinary, "exec", id, "sh", "-c",
   319  		"while ! test -e /tmp/execid1; do sleep 1; done")
   320  
   321  	if err = cmd.Start(); err != nil {
   322  		c.Fatalf("failed to start the exec cmd: %q", err)
   323  	}
   324  
   325  	// Give the exec 10 chances/seconds to start then give up and stop the test
   326  	tries := 10
   327  	for i := 0; i < tries; i++ {
   328  		// Since its still running we should see exec as part of the container
   329  		out, err = inspectField(id, "ExecIDs")
   330  		if err != nil {
   331  			c.Fatalf("failed to inspect container: %s, %v", out, err)
   332  		}
   333  
   334  		out = strings.TrimSuffix(out, "\n")
   335  		if out != "[]" && out != "<no value>" {
   336  			break
   337  		}
   338  		if i+1 == tries {
   339  			c.Fatalf("ExecIDs should not be empty, got: %s", out)
   340  		}
   341  		time.Sleep(1 * time.Second)
   342  	}
   343  
   344  	// Save execID for later
   345  	execID, err := inspectFilter(id, "index .ExecIDs 0")
   346  	if err != nil {
   347  		c.Fatalf("failed to get the exec id: %v", err)
   348  	}
   349  
   350  	// End the exec by creating the missing file
   351  	err = exec.Command(dockerBinary, "exec", id,
   352  		"sh", "-c", "touch /tmp/execid1").Run()
   353  
   354  	if err != nil {
   355  		c.Fatalf("failed to run the 2nd exec cmd: %q", err)
   356  	}
   357  
   358  	// Wait for 1st exec to complete
   359  	cmd.Wait()
   360  
   361  	// All execs for the container should be gone now
   362  	out, err = inspectField(id, "ExecIDs")
   363  	if err != nil {
   364  		c.Fatalf("failed to inspect container: %s, %v", out, err)
   365  	}
   366  
   367  	out = strings.TrimSuffix(out, "\n")
   368  	if out != "[]" && out != "<no value>" {
   369  		c.Fatalf("ExecIDs should be empty, got: %s", out)
   370  	}
   371  
   372  	// But we should still be able to query the execID
   373  	sc, body, err := sockRequest("GET", "/exec/"+execID+"/json", nil)
   374  	if sc != http.StatusOK {
   375  		c.Fatalf("received status != 200 OK: %d\n%s", sc, body)
   376  	}
   377  
   378  	// Now delete the container and then an 'inspect' on the exec should
   379  	// result in a 404 (not 'container not running')
   380  	out, ec := dockerCmd(c, "rm", "-f", id)
   381  	if ec != 0 {
   382  		c.Fatalf("error removing container: %s", out)
   383  	}
   384  	sc, body, err = sockRequest("GET", "/exec/"+execID+"/json", nil)
   385  	if sc != http.StatusNotFound {
   386  		c.Fatalf("received status != 404: %d\n%s", sc, body)
   387  	}
   388  }
   389  
   390  func (s *DockerSuite) TestLinksPingLinkedContainersOnRename(c *check.C) {
   391  	var out string
   392  	out, _ = dockerCmd(c, "run", "-d", "--name", "container1", "busybox", "top")
   393  	idA := strings.TrimSpace(out)
   394  	if idA == "" {
   395  		c.Fatal(out, "id should not be nil")
   396  	}
   397  	out, _ = dockerCmd(c, "run", "-d", "--link", "container1:alias1", "--name", "container2", "busybox", "top")
   398  	idB := strings.TrimSpace(out)
   399  	if idB == "" {
   400  		c.Fatal(out, "id should not be nil")
   401  	}
   402  
   403  	dockerCmd(c, "exec", "container2", "ping", "-c", "1", "alias1", "-W", "1")
   404  	dockerCmd(c, "rename", "container1", "container_new")
   405  	dockerCmd(c, "exec", "container2", "ping", "-c", "1", "alias1", "-W", "1")
   406  }
   407  
   408  func (s *DockerSuite) TestRunExecDir(c *check.C) {
   409  	testRequires(c, SameHostDaemon)
   410  
   411  	out, _ := dockerCmd(c, "run", "-d", "busybox", "top")
   412  	id := strings.TrimSpace(out)
   413  	execDir := filepath.Join(execDriverPath, id)
   414  	stateFile := filepath.Join(execDir, "state.json")
   415  
   416  	{
   417  		fi, err := os.Stat(execDir)
   418  		if err != nil {
   419  			c.Fatal(err)
   420  		}
   421  		if !fi.IsDir() {
   422  			c.Fatalf("%q must be a directory", execDir)
   423  		}
   424  		fi, err = os.Stat(stateFile)
   425  		if err != nil {
   426  			c.Fatal(err)
   427  		}
   428  	}
   429  
   430  	dockerCmd(c, "stop", id)
   431  	{
   432  		_, err := os.Stat(execDir)
   433  		if err == nil {
   434  			c.Fatal(err)
   435  		}
   436  		if err == nil {
   437  			c.Fatalf("Exec directory %q exists for removed container!", execDir)
   438  		}
   439  		if !os.IsNotExist(err) {
   440  			c.Fatalf("Error should be about non-existing, got %s", err)
   441  		}
   442  	}
   443  	dockerCmd(c, "start", id)
   444  	{
   445  		fi, err := os.Stat(execDir)
   446  		if err != nil {
   447  			c.Fatal(err)
   448  		}
   449  		if !fi.IsDir() {
   450  			c.Fatalf("%q must be a directory", execDir)
   451  		}
   452  		fi, err = os.Stat(stateFile)
   453  		if err != nil {
   454  			c.Fatal(err)
   455  		}
   456  	}
   457  	dockerCmd(c, "rm", "-f", id)
   458  	{
   459  		_, err := os.Stat(execDir)
   460  		if err == nil {
   461  			c.Fatal(err)
   462  		}
   463  		if err == nil {
   464  			c.Fatalf("Exec directory %q is exists for removed container!", execDir)
   465  		}
   466  		if !os.IsNotExist(err) {
   467  			c.Fatalf("Error should be about non-existing, got %s", err)
   468  		}
   469  	}
   470  }
   471  
   472  func (s *DockerSuite) TestRunMutableNetworkFiles(c *check.C) {
   473  	testRequires(c, SameHostDaemon)
   474  
   475  	for _, fn := range []string{"resolv.conf", "hosts"} {
   476  		deleteAllContainers()
   477  
   478  		content, err := runCommandAndReadContainerFile(fn, exec.Command(dockerBinary, "run", "-d", "--name", "c1", "busybox", "sh", "-c", fmt.Sprintf("echo success >/etc/%s && top", fn)))
   479  		if err != nil {
   480  			c.Fatal(err)
   481  		}
   482  
   483  		if strings.TrimSpace(string(content)) != "success" {
   484  			c.Fatal("Content was not what was modified in the container", string(content))
   485  		}
   486  
   487  		out, _ := dockerCmd(c, "run", "-d", "--name", "c2", "busybox", "top")
   488  		contID := strings.TrimSpace(out)
   489  		netFilePath := containerStorageFile(contID, fn)
   490  
   491  		f, err := os.OpenFile(netFilePath, os.O_WRONLY|os.O_SYNC|os.O_APPEND, 0644)
   492  		if err != nil {
   493  			c.Fatal(err)
   494  		}
   495  
   496  		if _, err := f.Seek(0, 0); err != nil {
   497  			f.Close()
   498  			c.Fatal(err)
   499  		}
   500  
   501  		if err := f.Truncate(0); err != nil {
   502  			f.Close()
   503  			c.Fatal(err)
   504  		}
   505  
   506  		if _, err := f.Write([]byte("success2\n")); err != nil {
   507  			f.Close()
   508  			c.Fatal(err)
   509  		}
   510  		f.Close()
   511  
   512  		res, _ := dockerCmd(c, "exec", contID, "cat", "/etc/"+fn)
   513  		if res != "success2\n" {
   514  			c.Fatalf("Expected content of %s: %q, got: %q", fn, "success2\n", res)
   515  		}
   516  	}
   517  }
   518  
   519  func (s *DockerSuite) TestExecWithUser(c *check.C) {
   520  	dockerCmd(c, "run", "-d", "--name", "parent", "busybox", "top")
   521  
   522  	out, _ := dockerCmd(c, "exec", "-u", "1", "parent", "id")
   523  	if !strings.Contains(out, "uid=1(daemon) gid=1(daemon)") {
   524  		c.Fatalf("exec with user by id expected daemon user got %s", out)
   525  	}
   526  
   527  	out, _ = dockerCmd(c, "exec", "-u", "root", "parent", "id")
   528  	if !strings.Contains(out, "uid=0(root) gid=0(root)") {
   529  		c.Fatalf("exec with user by root expected root user got %s", out)
   530  	}
   531  }
   532  
   533  func (s *DockerSuite) TestExecWithPrivileged(c *check.C) {
   534  
   535  	// Start main loop which attempts mknod repeatedly
   536  	dockerCmd(c, "run", "-d", "--name", "parent", "--cap-drop=ALL", "busybox", "sh", "-c", `while (true); do if [ -e /exec_priv ]; then cat /exec_priv && mknod /tmp/sda b 8 0 && echo "Success"; else echo "Privileged exec has not run yet"; fi; usleep 10000; done`)
   537  
   538  	// Check exec mknod doesn't work
   539  	cmd := exec.Command(dockerBinary, "exec", "parent", "sh", "-c", "mknod /tmp/sdb b 8 16")
   540  	out, _, err := runCommandWithOutput(cmd)
   541  	if err == nil || !strings.Contains(out, "Operation not permitted") {
   542  		c.Fatalf("exec mknod in --cap-drop=ALL container without --privileged should fail")
   543  	}
   544  
   545  	// Check exec mknod does work with --privileged
   546  	cmd = exec.Command(dockerBinary, "exec", "--privileged", "parent", "sh", "-c", `echo "Running exec --privileged" > /exec_priv && mknod /tmp/sdb b 8 16 && usleep 50000 && echo "Finished exec --privileged" > /exec_priv && echo ok`)
   547  	out, _, err = runCommandWithOutput(cmd)
   548  	if err != nil {
   549  		c.Fatal(err, out)
   550  	}
   551  
   552  	if actual := strings.TrimSpace(out); actual != "ok" {
   553  		c.Fatalf("exec mknod in --cap-drop=ALL container with --privileged failed: %v, output: %q", err, out)
   554  	}
   555  
   556  	// Check subsequent unprivileged exec cannot mknod
   557  	cmd = exec.Command(dockerBinary, "exec", "parent", "sh", "-c", "mknod /tmp/sdc b 8 32")
   558  	out, _, err = runCommandWithOutput(cmd)
   559  	if err == nil || !strings.Contains(out, "Operation not permitted") {
   560  		c.Fatalf("repeating exec mknod in --cap-drop=ALL container after --privileged without --privileged should fail")
   561  	}
   562  
   563  	// Confirm at no point was mknod allowed
   564  	logCmd := exec.Command(dockerBinary, "logs", "parent")
   565  	if out, _, err := runCommandWithOutput(logCmd); err != nil || strings.Contains(out, "Success") {
   566  		c.Fatal(out, err)
   567  	}
   568  
   569  }
   570  
   571  func (s *DockerSuite) TestExecWithImageUser(c *check.C) {
   572  	name := "testbuilduser"
   573  	_, err := buildImage(name,
   574  		`FROM busybox
   575  		RUN echo 'dockerio:x:1001:1001::/bin:/bin/false' >> /etc/passwd
   576  		USER dockerio`,
   577  		true)
   578  	if err != nil {
   579  		c.Fatalf("Could not build image %s: %v", name, err)
   580  	}
   581  
   582  	dockerCmd(c, "run", "-d", "--name", "dockerioexec", name, "top")
   583  
   584  	out, _ := dockerCmd(c, "exec", "dockerioexec", "whoami")
   585  	if !strings.Contains(out, "dockerio") {
   586  		c.Fatalf("exec with user by id expected dockerio user got %s", out)
   587  	}
   588  }
   589  
   590  func (s *DockerSuite) TestExecOnReadonlyContainer(c *check.C) {
   591  	dockerCmd(c, "run", "-d", "--read-only", "--name", "parent", "busybox", "top")
   592  	if _, status := dockerCmd(c, "exec", "parent", "true"); status != 0 {
   593  		c.Fatalf("exec into a read-only container failed with exit status %d", status)
   594  	}
   595  }
   596  
   597  // #15750
   598  func (s *DockerSuite) TestExecStartFails(c *check.C) {
   599  	name := "exec-15750"
   600  	dockerCmd(c, "run", "-d", "--name", name, "busybox", "top")
   601  
   602  	_, errmsg, status := dockerCmdWithStdoutStderr(nil, "exec", name, "no-such-cmd")
   603  	if status == 255 && !strings.Contains(errmsg, "executable file not found") {
   604  		c.Fatal("exec error message not received. The daemon might had crashed")
   605  	}
   606  }