Fix issue where plugin command error exit code is printed out

Signed-off-by: Corey Quon <corey.quon@docker.com>

cli-plugins/examples/helloworld/main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"context"
 	"fmt"
+	"os"
 
 	"github.com/docker/cli/cli-plugins/manager"
 	"github.com/docker/cli/cli-plugins/plugin"
@@ -33,6 +34,16 @@ func main() {
 			},
 		}
 
+		exitStatus2 := &cobra.Command{
+			Use:   "exitstatus2",
+			Short: "Exit with status 2",
+			RunE: func(_ *cobra.Command, _ []string) error {
+				fmt.Fprintln(dockerCli.Err(), "Exiting with error status 2")
+				os.Exit(2)
+				return nil
+			},
+		}
+
 		var who string
 		cmd := &cobra.Command{
 			Use:   "helloworld",
@@ -54,10 +65,11 @@ func main() {
 				return dockerCli.ConfigFile().Save()
 			},
 		}
+
 		flags := cmd.Flags()
 		flags.StringVar(&who, "who", "", "Who are we addressing?")
 
-		cmd.AddCommand(goodbye, apiversion)
+		cmd.AddCommand(goodbye, apiversion, exitStatus2)
 		return cmd
 	},
 		manager.Metadata{

cmd/docker/docker.go

@@ -4,7 +4,9 @@ import (
 	"errors"
 	"fmt"
 	"os"
+	"os/exec"
 	"strings"
+	"syscall"
 
 	"github.com/docker/cli/cli"
 	pluginmanager "github.com/docker/cli/cli-plugins/manager"
@@ -55,7 +57,21 @@ func newDockerCommand(dockerCli *command.DockerCli) *cobra.Command {
 				return err
 			}
 
-			return plugincmd.Run()
+			err = plugincmd.Run()
+			if err != nil {
+				statusCode := 1
+				exitErr, ok := err.(*exec.ExitError)
+				if !ok {
+					return err
+				}
+				if ws, ok := exitErr.Sys().(syscall.WaitStatus); ok {
+					statusCode = ws.ExitStatus()
+				}
+				return cli.StatusError{
+					StatusCode: statusCode,
+				}
+			}
+			return nil
 		},
 		PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
 			// flags must be the top-level command flags, not cmd.Flags()

e2e/cli-plugins/run_test.go

@@ -194,3 +194,16 @@ func TestCliInitialized(t *testing.T) {
 	assert.Assert(t, res.Stdout() != "")
 	assert.Assert(t, is.Equal(res.Stderr(), ""))
 }
+
+// TestPluginErrorCode tests when the plugin return with a given exit status.
+// We want to verify that the exit status does not get output to stdout and also that we return the exit code.
+func TestPluginErrorCode(t *testing.T) {
+	run, _, cleanup := prepare(t)
+	defer cleanup()
+	res := icmd.RunCmd(run("helloworld", "exitstatus2"))
+	res.Assert(t, icmd.Expected{
+		ExitCode: 2,
+		Err:      "Exiting with error status 2",
+	})
+	assert.Assert(t, is.Equal(res.Stdout(), ""))
+}

e2e/cli-plugins/testdata/docker-help-helloworld.golden

@@ -8,6 +8,7 @@ Options:
 
 Commands:
   apiversion  Print the API version of the server
+  exitstatus2 Exit with status 2
   goodbye     Say Goodbye instead of Hello
 
 Run 'docker helloworld COMMAND --help' for more information on a command.