@@ -7,6 +7,7 @@ import (

 	"fmt"

 	"io"

 	"io/ioutil"

+	"os"

 	"reflect"

 	"runtime"

 	"strings"

@@ -249,7 +250,10 @@ func Reload(configFile string, flags *pflag.FlagSet, reload func(*Config)) error

 	logrus.Infof("Got signal to reload configuration, reloading from: %s", configFile)

 	newConfig, err := getConflictFreeConfiguration(configFile, flags)

 	if err != nil {

-		return err

+		if flags.Changed("config-file") || !os.IsNotExist(err) {

+			return fmt.Errorf("unable to configure the Docker daemon with file %s: %v", configFile, err)

+		}

+		newConfig = New()

 	}

 	if err := Validate(newConfig); err != nil {

@@ -389,3 +389,49 @@ func discoveryConfig(backendAddr, advertiseAddr string, opts map[string]string)

 		},

 	}

 }

+

+// TestReloadSetConfigFileNotExist tests that when `--config-file` is set

+// and it doesn't exist the `Reload` function returns an error.

+func TestReloadSetConfigFileNotExist(t *testing.T) {

+	configFile := "/tmp/blabla/not/exists/config.json"

+	flags := pflag.NewFlagSet("test", pflag.ContinueOnError)

+	flags.String("config-file", "", "")

+	flags.Set("config-file", configFile)

+

+	err := Reload(configFile, flags, func(c *Config) {})

+	assert.Error(t, err)

+	testutil.ErrorContains(t, err, "unable to configure the Docker daemon with file")

+}

+

+// TestReloadDefaultConfigNotExist tests that if the default configuration file

+// doesn't exist the daemon still will be reloaded.

+func TestReloadDefaultConfigNotExist(t *testing.T) {

+	reloaded := false

+	configFile := "/etc/docker/daemon.json"

+	flags := pflag.NewFlagSet("test", pflag.ContinueOnError)

+	flags.String("config-file", configFile, "")

+	err := Reload(configFile, flags, func(c *Config) {

+		reloaded = true

+	})

+	assert.Nil(t, err)

+	assert.True(t, reloaded)

+}

+

+// TestReloadBadDefaultConfig tests that when `--config-file` is not set

+// and the default configuration file exists and is bad return an error

+func TestReloadBadDefaultConfig(t *testing.T) {

+	f, err := ioutil.TempFile("", "docker-config-")

+	if err != nil {

+		t.Fatal(err)

+	}

+

+	configFile := f.Name()

+	f.Write([]byte(`{wrong: "configuration"}`))

+	f.Close()

+

+	flags := pflag.NewFlagSet("test", pflag.ContinueOnError)

+	flags.String("config-file", configFile, "")

+	err = Reload(configFile, flags, func(c *Config) {})

+	assert.Error(t, err)

+	testutil.ErrorContains(t, err, "unable to configure the Docker daemon with file")

+}