Restore --default-gateway{,-v6} daemon options.

This was added before the libnetwork merge, and then lost. Fixes #13755.

Signed-off-by: Eric-Olivier Lamey <eo@lamey.me>

daemon/config_linux.go

@@ -42,8 +42,8 @@ type bridgeConfig struct {
 	IP                          string
 	FixedCIDR                   string
 	FixedCIDRv6                 string
-	DefaultGatewayIPv4          string
-	DefaultGatewayIPv6          string
+	DefaultGatewayIPv4          net.IP
+	DefaultGatewayIPv6          net.IP
 	InterContainerCommunication bool
 }
 
@@ -68,8 +68,8 @@ func (config *Config) InstallFlags() {
 	flag.StringVar(&config.Bridge.Iface, []string{"b", "-bridge"}, "", "Attach containers to a network bridge")
 	flag.StringVar(&config.Bridge.FixedCIDR, []string{"-fixed-cidr"}, "", "IPv4 subnet for fixed IPs")
 	flag.StringVar(&config.Bridge.FixedCIDRv6, []string{"-fixed-cidr-v6"}, "", "IPv6 subnet for fixed IPs")
-	flag.StringVar(&config.Bridge.DefaultGatewayIPv4, []string{"-default-gateway"}, "", "Container default gateway IPv4 address")
-	flag.StringVar(&config.Bridge.DefaultGatewayIPv6, []string{"-default-gateway-v6"}, "", "Container default gateway IPv6 address")
+	opts.IPVar(&config.Bridge.DefaultGatewayIPv4, []string{"-default-gateway"}, "", "Container default gateway IPv4 address")
+	opts.IPVar(&config.Bridge.DefaultGatewayIPv6, []string{"-default-gateway-v6"}, "", "Container default gateway IPv6 address")
 	flag.BoolVar(&config.Bridge.InterContainerCommunication, []string{"#icc", "-icc"}, true, "Enable inter-container communication")
 	opts.IPVar(&config.Bridge.DefaultIP, []string{"#ip", "-ip"}, "0.0.0.0", "Default IP when binding container ports")
 	flag.BoolVar(&config.Bridge.EnableUserlandProxy, []string{"-userland-proxy"}, true, "Use userland proxy for loopback traffic")

daemon/daemon.go

@@ -946,6 +946,14 @@ func initNetworkController(config *Config) (libnetwork.NetworkController, error)
 		netOption["FixedCIDRv6"] = fCIDRv6
 	}
 
+	if config.Bridge.DefaultGatewayIPv4 != nil {
+		netOption["DefaultGatewayIPv4"] = config.Bridge.DefaultGatewayIPv4
+	}
+
+	if config.Bridge.DefaultGatewayIPv6 != nil {
+		netOption["DefaultGatewayIPv6"] = config.Bridge.DefaultGatewayIPv6
+	}
+
 	// --ip processing
 	if config.Bridge.DefaultIP != nil {
 		netOption["DefaultBindingIP"] = config.Bridge.DefaultIP

integration-cli/docker_cli_daemon_test.go

@@ -526,6 +526,49 @@ func (s *DockerDaemonSuite) TestDaemonBridgeFixedCidr(c *check.C) {
 	}
 }
 
+func (s *DockerDaemonSuite) TestDaemonDefaultGatewayIPv4Implicit(c *check.C) {
+	defaultNetworkBridge := "docker0"
+	deleteInterface(c, defaultNetworkBridge)
+
+	d := s.d
+
+	bridgeIp := "192.169.1.1"
+	bridgeIpNet := fmt.Sprintf("%s/24", bridgeIp)
+
+	err := d.StartWithBusybox("--bip", bridgeIpNet)
+	c.Assert(err, check.IsNil)
+	defer d.Restart()
+
+	expectedMessage := fmt.Sprintf("default via %s dev", bridgeIp)
+	out, err := d.Cmd("run", "busybox", "ip", "-4", "route", "list", "0/0")
+	c.Assert(strings.Contains(out, expectedMessage), check.Equals, true,
+		check.Commentf("Implicit default gateway should be bridge IP %s, but default route was '%s'",
+			bridgeIp, strings.TrimSpace(out)))
+	deleteInterface(c, defaultNetworkBridge)
+}
+
+func (s *DockerDaemonSuite) TestDaemonDefaultGatewayIPv4Explicit(c *check.C) {
+	defaultNetworkBridge := "docker0"
+	deleteInterface(c, defaultNetworkBridge)
+
+	d := s.d
+
+	bridgeIp := "192.169.1.1"
+	bridgeIpNet := fmt.Sprintf("%s/24", bridgeIp)
+	gatewayIp := "192.169.1.254"
+
+	err := d.StartWithBusybox("--bip", bridgeIpNet, "--default-gateway", gatewayIp)
+	c.Assert(err, check.IsNil)
+	defer d.Restart()
+
+	expectedMessage := fmt.Sprintf("default via %s dev", gatewayIp)
+	out, err := d.Cmd("run", "busybox", "ip", "-4", "route", "list", "0/0")
+	c.Assert(strings.Contains(out, expectedMessage), check.Equals, true,
+		check.Commentf("Explicit default gateway should be %s, but default route was '%s'",
+			gatewayIp, strings.TrimSpace(out)))
+	deleteInterface(c, defaultNetworkBridge)
+}
+
 func (s *DockerDaemonSuite) TestDaemonIP(c *check.C) {
 	d := s.d