github.com/uriddle/docker@v0.0.0-20210926094723-4072e6aeb013/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/docker/docker/pkg/integration/checker"
    19  	"github.com/go-check/check"
    20  )
    21  
    22  func (s *DockerSuite) TestExec(c *check.C) {
    23  	testRequires(c, DaemonIsLinux)
    24  	dockerCmd(c, "run", "-d", "--name", "testing", "busybox", "sh", "-c", "echo test > /tmp/file && top")
    25  
    26  	out, _ := dockerCmd(c, "exec", "testing", "cat", "/tmp/file")
    27  	out = strings.Trim(out, "\r\n")
    28  	c.Assert(out, checker.Equals, "test")
    29  
    30  }
    31  
    32  func (s *DockerSuite) TestExecInteractive(c *check.C) {
    33  	testRequires(c, DaemonIsLinux)
    34  	dockerCmd(c, "run", "-d", "--name", "testing", "busybox", "sh", "-c", "echo test > /tmp/file && top")
    35  
    36  	execCmd := exec.Command(dockerBinary, "exec", "-i", "testing", "sh")
    37  	stdin, err := execCmd.StdinPipe()
    38  	c.Assert(err, checker.IsNil)
    39  	stdout, err := execCmd.StdoutPipe()
    40  	c.Assert(err, checker.IsNil)
    41  
    42  	err = execCmd.Start()
    43  	c.Assert(err, checker.IsNil)
    44  	_, err = stdin.Write([]byte("cat /tmp/file\n"))
    45  	c.Assert(err, checker.IsNil)
    46  
    47  	r := bufio.NewReader(stdout)
    48  	line, err := r.ReadString('\n')
    49  	c.Assert(err, checker.IsNil)
    50  	line = strings.TrimSpace(line)
    51  	c.Assert(line, checker.Equals, "test")
    52  	err = stdin.Close()
    53  	c.Assert(err, checker.IsNil)
    54  	errChan := make(chan error)
    55  	go func() {
    56  		errChan <- execCmd.Wait()
    57  		close(errChan)
    58  	}()
    59  	select {
    60  	case err := <-errChan:
    61  		c.Assert(err, checker.IsNil)
    62  	case <-time.After(1 * time.Second):
    63  		c.Fatal("docker exec failed to exit on stdin close")
    64  	}
    65  
    66  }
    67  
    68  func (s *DockerSuite) TestExecAfterContainerRestart(c *check.C) {
    69  	testRequires(c, DaemonIsLinux)
    70  	out, _ := dockerCmd(c, "run", "-d", "busybox", "top")
    71  	cleanedContainerID := strings.TrimSpace(out)
    72  	c.Assert(waitRun(cleanedContainerID), check.IsNil)
    73  	dockerCmd(c, "restart", cleanedContainerID)
    74  	c.Assert(waitRun(cleanedContainerID), check.IsNil)
    75  
    76  	out, _ = dockerCmd(c, "exec", cleanedContainerID, "echo", "hello")
    77  	outStr := strings.TrimSpace(out)
    78  	c.Assert(outStr, checker.Equals, "hello")
    79  }
    80  
    81  func (s *DockerDaemonSuite) TestExecAfterDaemonRestart(c *check.C) {
    82  	testRequires(c, DaemonIsLinux)
    83  	testRequires(c, SameHostDaemon)
    84  
    85  	err := s.d.StartWithBusybox()
    86  	c.Assert(err, checker.IsNil)
    87  
    88  	out, err := s.d.Cmd("run", "-d", "--name", "top", "-p", "80", "busybox:latest", "top")
    89  	c.Assert(err, checker.IsNil, check.Commentf("Could not run top: %s", out))
    90  
    91  	err = s.d.Restart()
    92  	c.Assert(err, checker.IsNil, check.Commentf("Could not restart daemon"))
    93  
    94  	out, err = s.d.Cmd("start", "top")
    95  	c.Assert(err, checker.IsNil, check.Commentf("Could not start top after daemon restart: %s", out))
    96  
    97  	out, err = s.d.Cmd("exec", "top", "echo", "hello")
    98  	c.Assert(err, checker.IsNil, check.Commentf("Could not exec on container top: %s", out))
    99  
   100  	outStr := strings.TrimSpace(string(out))
   101  	c.Assert(outStr, checker.Equals, "hello")
   102  }
   103  
   104  // Regression test for #9155, #9044
   105  func (s *DockerSuite) TestExecEnv(c *check.C) {
   106  	testRequires(c, DaemonIsLinux)
   107  	dockerCmd(c, "run", "-e", "LALA=value1", "-e", "LALA=value2",
   108  		"-d", "--name", "testing", "busybox", "top")
   109  	c.Assert(waitRun("testing"), check.IsNil)
   110  
   111  	out, _ := dockerCmd(c, "exec", "testing", "env")
   112  	c.Assert(out, checker.Not(checker.Contains), "LALA=value1")
   113  	c.Assert(out, checker.Contains, "LALA=value2")
   114  	c.Assert(out, checker.Contains, "HOME=/root")
   115  }
   116  
   117  func (s *DockerSuite) TestExecExitStatus(c *check.C) {
   118  	testRequires(c, DaemonIsLinux)
   119  	dockerCmd(c, "run", "-d", "--name", "top", "busybox", "top")
   120  
   121  	// Test normal (non-detached) case first
   122  	cmd := exec.Command(dockerBinary, "exec", "top", "sh", "-c", "exit 23")
   123  	ec, _ := runCommand(cmd)
   124  	c.Assert(ec, checker.Equals, 23)
   125  }
   126  
   127  func (s *DockerSuite) TestExecPausedContainer(c *check.C) {
   128  	testRequires(c, DaemonIsLinux)
   129  	defer unpauseAllContainers()
   130  
   131  	out, _ := dockerCmd(c, "run", "-d", "--name", "testing", "busybox", "top")
   132  	ContainerID := strings.TrimSpace(out)
   133  
   134  	dockerCmd(c, "pause", "testing")
   135  	out, _, err := dockerCmdWithError("exec", "-i", "-t", ContainerID, "echo", "hello")
   136  	c.Assert(err, checker.NotNil, check.Commentf("container should fail to exec new conmmand if it is paused"))
   137  
   138  	expected := ContainerID + " is paused, unpause the container before exec"
   139  	c.Assert(out, checker.Contains, expected, check.Commentf("container should not exec new command if it is paused"))
   140  }
   141  
   142  // regression test for #9476
   143  func (s *DockerSuite) TestExecTtyCloseStdin(c *check.C) {
   144  	testRequires(c, DaemonIsLinux)
   145  	dockerCmd(c, "run", "-d", "-it", "--name", "exec_tty_stdin", "busybox")
   146  
   147  	cmd := exec.Command(dockerBinary, "exec", "-i", "exec_tty_stdin", "cat")
   148  	stdinRw, err := cmd.StdinPipe()
   149  	c.Assert(err, checker.IsNil)
   150  
   151  	stdinRw.Write([]byte("test"))
   152  	stdinRw.Close()
   153  
   154  	out, _, err := runCommandWithOutput(cmd)
   155  	c.Assert(err, checker.IsNil, check.Commentf(out))
   156  
   157  	out, _ = dockerCmd(c, "top", "exec_tty_stdin")
   158  	outArr := strings.Split(out, "\n")
   159  	c.Assert(len(outArr), checker.LessOrEqualThan, 3, check.Commentf("exec process left running"))
   160  	c.Assert(out, checker.Not(checker.Contains), "nsenter-exec")
   161  }
   162  
   163  func (s *DockerSuite) TestExecTtyWithoutStdin(c *check.C) {
   164  	testRequires(c, DaemonIsLinux)
   165  	out, _ := dockerCmd(c, "run", "-d", "-ti", "busybox")
   166  	id := strings.TrimSpace(out)
   167  	c.Assert(waitRun(id), checker.IsNil)
   168  
   169  	errChan := make(chan error)
   170  	go func() {
   171  		defer close(errChan)
   172  
   173  		cmd := exec.Command(dockerBinary, "exec", "-ti", id, "true")
   174  		if _, err := cmd.StdinPipe(); err != nil {
   175  			errChan <- err
   176  			return
   177  		}
   178  
   179  		expected := "cannot enable tty mode"
   180  		if out, _, err := runCommandWithOutput(cmd); err == nil {
   181  			errChan <- fmt.Errorf("exec should have failed")
   182  			return
   183  		} else if !strings.Contains(out, expected) {
   184  			errChan <- fmt.Errorf("exec failed with error %q: expected %q", out, expected)
   185  			return
   186  		}
   187  	}()
   188  
   189  	select {
   190  	case err := <-errChan:
   191  		c.Assert(err, check.IsNil)
   192  	case <-time.After(3 * time.Second):
   193  		c.Fatal("exec is running but should have failed")
   194  	}
   195  }
   196  
   197  func (s *DockerSuite) TestExecParseError(c *check.C) {
   198  	testRequires(c, DaemonIsLinux)
   199  	dockerCmd(c, "run", "-d", "--name", "top", "busybox", "top")
   200  
   201  	// Test normal (non-detached) case first
   202  	cmd := exec.Command(dockerBinary, "exec", "top")
   203  	_, stderr, _, err := runCommandWithStdoutStderr(cmd)
   204  	c.Assert(err, checker.NotNil)
   205  	c.Assert(stderr, checker.Contains, "See '"+dockerBinary+" exec --help'")
   206  }
   207  
   208  func (s *DockerSuite) TestExecStopNotHanging(c *check.C) {
   209  	testRequires(c, DaemonIsLinux)
   210  	dockerCmd(c, "run", "-d", "--name", "testing", "busybox", "top")
   211  
   212  	err := exec.Command(dockerBinary, "exec", "testing", "top").Start()
   213  	c.Assert(err, checker.IsNil)
   214  
   215  	type dstop struct {
   216  		out []byte
   217  		err error
   218  	}
   219  
   220  	ch := make(chan dstop)
   221  	go func() {
   222  		out, err := exec.Command(dockerBinary, "stop", "testing").CombinedOutput()
   223  		ch <- dstop{out, err}
   224  		close(ch)
   225  	}()
   226  	select {
   227  	case <-time.After(3 * time.Second):
   228  		c.Fatal("Container stop timed out")
   229  	case s := <-ch:
   230  		c.Assert(s.err, check.IsNil)
   231  	}
   232  }
   233  
   234  func (s *DockerSuite) TestExecCgroup(c *check.C) {
   235  	testRequires(c, NotUserNamespace)
   236  	testRequires(c, DaemonIsLinux)
   237  	dockerCmd(c, "run", "-d", "--name", "testing", "busybox", "top")
   238  
   239  	out, _ := dockerCmd(c, "exec", "testing", "cat", "/proc/1/cgroup")
   240  	containerCgroups := sort.StringSlice(strings.Split(out, "\n"))
   241  
   242  	var wg sync.WaitGroup
   243  	var mu sync.Mutex
   244  	execCgroups := []sort.StringSlice{}
   245  	errChan := make(chan error)
   246  	// exec a few times concurrently to get consistent failure
   247  	for i := 0; i < 5; i++ {
   248  		wg.Add(1)
   249  		go func() {
   250  			out, _, err := dockerCmdWithError("exec", "testing", "cat", "/proc/self/cgroup")
   251  			if err != nil {
   252  				errChan <- err
   253  				return
   254  			}
   255  			cg := sort.StringSlice(strings.Split(out, "\n"))
   256  
   257  			mu.Lock()
   258  			execCgroups = append(execCgroups, cg)
   259  			mu.Unlock()
   260  			wg.Done()
   261  		}()
   262  	}
   263  	wg.Wait()
   264  	close(errChan)
   265  
   266  	for err := range errChan {
   267  		c.Assert(err, checker.IsNil)
   268  	}
   269  
   270  	for _, cg := range execCgroups {
   271  		if !reflect.DeepEqual(cg, containerCgroups) {
   272  			fmt.Println("exec cgroups:")
   273  			for _, name := range cg {
   274  				fmt.Printf(" %s\n", name)
   275  			}
   276  
   277  			fmt.Println("container cgroups:")
   278  			for _, name := range containerCgroups {
   279  				fmt.Printf(" %s\n", name)
   280  			}
   281  			c.Fatal("cgroups mismatched")
   282  		}
   283  	}
   284  }
   285  
   286  func (s *DockerSuite) TestInspectExecID(c *check.C) {
   287  	testRequires(c, DaemonIsLinux)
   288  	out, _ := dockerCmd(c, "run", "-d", "busybox", "top")
   289  	id := strings.TrimSuffix(out, "\n")
   290  
   291  	out, err := inspectField(id, "ExecIDs")
   292  	c.Assert(err, checker.IsNil, check.Commentf("failed to inspect container: %s", out))
   293  	c.Assert(out, checker.Equals, "[]", check.Commentf("ExecIDs should be empty, got: %s", out))
   294  
   295  	// Start an exec, have it block waiting so we can do some checking
   296  	cmd := exec.Command(dockerBinary, "exec", id, "sh", "-c",
   297  		"while ! test -e /tmp/execid1; do sleep 1; done")
   298  
   299  	err = cmd.Start()
   300  	c.Assert(err, checker.IsNil, check.Commentf("failed to start the exec cmd"))
   301  
   302  	// Give the exec 10 chances/seconds to start then give up and stop the test
   303  	tries := 10
   304  	for i := 0; i < tries; i++ {
   305  		// Since its still running we should see exec as part of the container
   306  		out, err = inspectField(id, "ExecIDs")
   307  		c.Assert(err, checker.IsNil, check.Commentf("failed to inspect container: %s", out))
   308  
   309  		out = strings.TrimSuffix(out, "\n")
   310  		if out != "[]" && out != "<no value>" {
   311  			break
   312  		}
   313  		c.Assert(i+1, checker.Not(checker.Equals), tries, check.Commentf("ExecIDs should be empty, got: %s", out))
   314  		time.Sleep(1 * time.Second)
   315  	}
   316  
   317  	// Save execID for later
   318  	execID, err := inspectFilter(id, "index .ExecIDs 0")
   319  	c.Assert(err, checker.IsNil, check.Commentf("failed to get the exec id"))
   320  
   321  	// End the exec by creating the missing file
   322  	err = exec.Command(dockerBinary, "exec", id,
   323  		"sh", "-c", "touch /tmp/execid1").Run()
   324  
   325  	c.Assert(err, checker.IsNil, check.Commentf("failed to run the 2nd exec cmd"))
   326  
   327  	// Wait for 1st exec to complete
   328  	cmd.Wait()
   329  
   330  	// All execs for the container should be gone now
   331  	out, err = inspectField(id, "ExecIDs")
   332  	c.Assert(err, checker.IsNil, check.Commentf("failed to inspect container: %s", out))
   333  
   334  	out = strings.TrimSuffix(out, "\n")
   335  	c.Assert(out == "[]" || out == "<no value>", checker.True)
   336  
   337  	// But we should still be able to query the execID
   338  	sc, body, err := sockRequest("GET", "/exec/"+execID+"/json", nil)
   339  	c.Assert(sc, checker.Equals, http.StatusOK, check.Commentf("received status != 200 OK: %d\n%s", sc, body))
   340  
   341  	// Now delete the container and then an 'inspect' on the exec should
   342  	// result in a 404 (not 'container not running')
   343  	out, ec := dockerCmd(c, "rm", "-f", id)
   344  	c.Assert(ec, checker.Equals, 0, check.Commentf("error removing container: %s", out))
   345  	sc, body, err = sockRequest("GET", "/exec/"+execID+"/json", nil)
   346  	c.Assert(sc, checker.Equals, http.StatusNotFound, check.Commentf("received status != 404: %d\n%s", sc, body))
   347  }
   348  
   349  func (s *DockerSuite) TestLinksPingLinkedContainersOnRename(c *check.C) {
   350  	testRequires(c, DaemonIsLinux)
   351  	var out string
   352  	out, _ = dockerCmd(c, "run", "-d", "--name", "container1", "busybox", "top")
   353  	idA := strings.TrimSpace(out)
   354  	c.Assert(idA, checker.Not(checker.Equals), "", check.Commentf("%s, id should not be nil", out))
   355  	out, _ = dockerCmd(c, "run", "-d", "--link", "container1:alias1", "--name", "container2", "busybox", "top")
   356  	idB := strings.TrimSpace(out)
   357  	c.Assert(idB, checker.Not(checker.Equals), "", check.Commentf("%s, id should not be nil", out))
   358  
   359  	dockerCmd(c, "exec", "container2", "ping", "-c", "1", "alias1", "-W", "1")
   360  	dockerCmd(c, "rename", "container1", "container_new")
   361  	dockerCmd(c, "exec", "container2", "ping", "-c", "1", "alias1", "-W", "1")
   362  }
   363  
   364  func (s *DockerSuite) TestRunExecDir(c *check.C) {
   365  	testRequires(c, SameHostDaemon, DaemonIsLinux)
   366  
   367  	out, _ := dockerCmd(c, "run", "-d", "busybox", "top")
   368  	id := strings.TrimSpace(out)
   369  	execDir := filepath.Join(execDriverPath, id)
   370  	stateFile := filepath.Join(execDir, "state.json")
   371  
   372  	{
   373  		fi, err := os.Stat(execDir)
   374  		c.Assert(err, checker.IsNil)
   375  		if !fi.IsDir() {
   376  			c.Fatalf("%q must be a directory", execDir)
   377  		}
   378  		fi, err = os.Stat(stateFile)
   379  		c.Assert(err, checker.IsNil)
   380  	}
   381  
   382  	dockerCmd(c, "stop", id)
   383  	{
   384  		_, err := os.Stat(execDir)
   385  		c.Assert(err, checker.NotNil)
   386  		c.Assert(err, checker.NotNil, check.Commentf("Exec directory %q exists for removed container!", execDir))
   387  		if !os.IsNotExist(err) {
   388  			c.Fatalf("Error should be about non-existing, got %s", err)
   389  		}
   390  	}
   391  	dockerCmd(c, "start", id)
   392  	{
   393  		fi, err := os.Stat(execDir)
   394  		c.Assert(err, checker.IsNil)
   395  		if !fi.IsDir() {
   396  			c.Fatalf("%q must be a directory", execDir)
   397  		}
   398  		fi, err = os.Stat(stateFile)
   399  		c.Assert(err, checker.IsNil)
   400  	}
   401  	dockerCmd(c, "rm", "-f", id)
   402  	{
   403  		_, err := os.Stat(execDir)
   404  		c.Assert(err, checker.NotNil, check.Commentf("Exec directory %q exists for removed container!", execDir))
   405  		if !os.IsNotExist(err) {
   406  			c.Fatalf("Error should be about non-existing, got %s", err)
   407  		}
   408  	}
   409  }
   410  
   411  func (s *DockerSuite) TestRunMutableNetworkFiles(c *check.C) {
   412  	testRequires(c, SameHostDaemon, DaemonIsLinux)
   413  	for _, fn := range []string{"resolv.conf", "hosts"} {
   414  		deleteAllContainers()
   415  
   416  		content, err := runCommandAndReadContainerFile(fn, exec.Command(dockerBinary, "run", "-d", "--name", "c1", "busybox", "sh", "-c", fmt.Sprintf("echo success >/etc/%s && top", fn)))
   417  		c.Assert(err, checker.IsNil)
   418  
   419  		c.Assert(strings.TrimSpace(string(content)), checker.Equals, "success", check.Commentf("Content was not what was modified in the container", string(content)))
   420  
   421  		out, _ := dockerCmd(c, "run", "-d", "--name", "c2", "busybox", "top")
   422  		contID := strings.TrimSpace(out)
   423  		netFilePath := containerStorageFile(contID, fn)
   424  
   425  		f, err := os.OpenFile(netFilePath, os.O_WRONLY|os.O_SYNC|os.O_APPEND, 0644)
   426  		c.Assert(err, checker.IsNil)
   427  
   428  		if _, err := f.Seek(0, 0); err != nil {
   429  			f.Close()
   430  			c.Fatal(err)
   431  		}
   432  
   433  		if err := f.Truncate(0); err != nil {
   434  			f.Close()
   435  			c.Fatal(err)
   436  		}
   437  
   438  		if _, err := f.Write([]byte("success2\n")); err != nil {
   439  			f.Close()
   440  			c.Fatal(err)
   441  		}
   442  		f.Close()
   443  
   444  		res, _ := dockerCmd(c, "exec", contID, "cat", "/etc/"+fn)
   445  		c.Assert(res, checker.Equals, "success2\n")
   446  	}
   447  }
   448  
   449  func (s *DockerSuite) TestExecWithUser(c *check.C) {
   450  	testRequires(c, DaemonIsLinux)
   451  	dockerCmd(c, "run", "-d", "--name", "parent", "busybox", "top")
   452  
   453  	out, _ := dockerCmd(c, "exec", "-u", "1", "parent", "id")
   454  	c.Assert(out, checker.Contains, "uid=1(daemon) gid=1(daemon)")
   455  
   456  	out, _ = dockerCmd(c, "exec", "-u", "root", "parent", "id")
   457  	c.Assert(out, checker.Contains, "uid=0(root) gid=0(root)", check.Commentf("exec with user by id expected daemon user got %s", out))
   458  }
   459  
   460  func (s *DockerSuite) TestExecWithPrivileged(c *check.C) {
   461  	testRequires(c, DaemonIsLinux, NotUserNamespace)
   462  	// Start main loop which attempts mknod repeatedly
   463  	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`)
   464  
   465  	// Check exec mknod doesn't work
   466  	cmd := exec.Command(dockerBinary, "exec", "parent", "sh", "-c", "mknod /tmp/sdb b 8 16")
   467  	out, _, err := runCommandWithOutput(cmd)
   468  	c.Assert(err, checker.NotNil, check.Commentf("exec mknod in --cap-drop=ALL container without --privileged should fail"))
   469  	c.Assert(out, checker.Contains, "Operation not permitted", check.Commentf("exec mknod in --cap-drop=ALL container without --privileged should fail"))
   470  
   471  	// Check exec mknod does work with --privileged
   472  	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`)
   473  	out, _, err = runCommandWithOutput(cmd)
   474  	c.Assert(err, checker.IsNil)
   475  
   476  	actual := strings.TrimSpace(out)
   477  	c.Assert(actual, checker.Equals, "ok", check.Commentf("exec mknod in --cap-drop=ALL container with --privileged failed, output: %q", out))
   478  
   479  	// Check subsequent unprivileged exec cannot mknod
   480  	cmd = exec.Command(dockerBinary, "exec", "parent", "sh", "-c", "mknod /tmp/sdc b 8 32")
   481  	out, _, err = runCommandWithOutput(cmd)
   482  	c.Assert(err, checker.NotNil, check.Commentf("repeating exec mknod in --cap-drop=ALL container after --privileged without --privileged should fail"))
   483  	c.Assert(out, checker.Contains, "Operation not permitted", check.Commentf("repeating exec mknod in --cap-drop=ALL container after --privileged without --privileged should fail"))
   484  
   485  	// Confirm at no point was mknod allowed
   486  	logCmd := exec.Command(dockerBinary, "logs", "parent")
   487  	out, _, err = runCommandWithOutput(logCmd)
   488  	c.Assert(err, checker.IsNil)
   489  	c.Assert(out, checker.Not(checker.Contains), "Success")
   490  
   491  }
   492  
   493  func (s *DockerSuite) TestExecWithImageUser(c *check.C) {
   494  	testRequires(c, DaemonIsLinux)
   495  	name := "testbuilduser"
   496  	_, err := buildImage(name,
   497  		`FROM busybox
   498  		RUN echo 'dockerio:x:1001:1001::/bin:/bin/false' >> /etc/passwd
   499  		USER dockerio`,
   500  		true)
   501  	c.Assert(err, checker.IsNil)
   502  
   503  	dockerCmd(c, "run", "-d", "--name", "dockerioexec", name, "top")
   504  
   505  	out, _ := dockerCmd(c, "exec", "dockerioexec", "whoami")
   506  	c.Assert(out, checker.Contains, "dockerio", check.Commentf("exec with user by id expected dockerio user got %s", out))
   507  }
   508  
   509  func (s *DockerSuite) TestExecOnReadonlyContainer(c *check.C) {
   510  	// --read-only + userns has remount issues
   511  	testRequires(c, DaemonIsLinux, NotUserNamespace)
   512  	dockerCmd(c, "run", "-d", "--read-only", "--name", "parent", "busybox", "top")
   513  	dockerCmd(c, "exec", "parent", "true")
   514  }
   515  
   516  // #15750
   517  func (s *DockerSuite) TestExecStartFails(c *check.C) {
   518  	testRequires(c, DaemonIsLinux)
   519  	name := "exec-15750"
   520  	dockerCmd(c, "run", "-d", "--name", name, "busybox", "top")
   521  	c.Assert(waitRun(name), checker.IsNil)
   522  
   523  	out, _, err := dockerCmdWithError("exec", name, "no-such-cmd")
   524  	c.Assert(err, checker.NotNil, check.Commentf(out))
   525  	c.Assert(out, checker.Contains, "executable file not found")
   526  }