feat: configure custom IP for default bridge network

Signed-off-by: Swagat Bora <swagatbora90@gmail.com>

cmd/nerdctl/helpers/flagutil.go

@@ -99,6 +99,10 @@ func ProcessRootCmdFlags(cmd *cobra.Command) (types.GlobalCommandOptions, error)
 	if err != nil {
 		return types.GlobalCommandOptions{}, err
 	}
+	bridgeIP, err := cmd.Flags().GetString("bridge-ip")
+	if err != nil {
+		return types.GlobalCommandOptions{}, err
+	}
 	return types.GlobalCommandOptions{
 		Debug:            debug,
 		DebugFull:        debugFull,
@@ -113,6 +117,7 @@ func ProcessRootCmdFlags(cmd *cobra.Command) (types.GlobalCommandOptions, error)
 		HostsDir:         hostsDir,
 		Experimental:     experimental,
 		HostGatewayIP:    hostGatewayIP,
+		BridgeIP:         bridgeIP,
 	}, nil
 }
 

cmd/nerdctl/internal/internal_oci_hook.go

@@ -56,9 +56,11 @@ func internalOCIHookAction(cmd *cobra.Command, args []string) error {
 	}
 	cniPath := globalOptions.CNIPath
 	cniNetconfpath := globalOptions.CNINetConfPath
+	bridgeIP := globalOptions.BridgeIP
 	return ocihook.Run(os.Stdin, os.Stderr, event,
 		dataStore,
 		cniPath,
 		cniNetconfpath,
+		bridgeIP,
 	)
 }

cmd/nerdctl/main.go

@@ -183,6 +183,7 @@ func initRootCmdFlags(rootCmd *cobra.Command, tomlPath string) (*pflag.FlagSet,
 	// Experimental enable experimental feature, see in https://github.com/containerd/nerdctl/blob/main/docs/experimental.md
 	helpers.AddPersistentBoolFlag(rootCmd, "experimental", nil, nil, cfg.Experimental, "NERDCTL_EXPERIMENTAL", "Control experimental: https://github.com/containerd/nerdctl/blob/main/docs/experimental.md")
 	helpers.AddPersistentStringFlag(rootCmd, "host-gateway-ip", nil, nil, nil, aliasToBeInherited, cfg.HostGatewayIP, "NERDCTL_HOST_GATEWAY_IP", "IP address that the special 'host-gateway' string in --add-host resolves to. Defaults to the IP address of the host. It has no effect without setting --add-host")
+	helpers.AddPersistentStringFlag(rootCmd, "bridge-ip", nil, nil, nil, aliasToBeInherited, cfg.BridgeIP, "NERDCTL_BRIDGE_IP", "IP address for the default nerdctl bridge network")
 	return aliasToBeInherited, nil
 }
 

docs/config.md

@@ -45,6 +45,7 @@ experimental   = true
 | `hosts_dir`         | `--hosts-dir`                      |                           | `certs.d` directory                                                                                                                                              | Since 0.16.0     |
 | `experimental`      | `--experimental`                   | `NERDCTL_EXPERIMENTAL`    | Enable  [experimental features](experimental.md)                                                                                                                 | Since 0.22.3     |
 | `host_gateway_ip`   | `--host-gateway-ip`                | `NERDCTL_HOST_GATEWAY_IP` | IP address that the special 'host-gateway' string in --add-host resolves to. Defaults to the IP address of the host. It has no effect without setting --add-host | Since 1.3.0      |
+| `bridge_ip`         | `--bridge-ip`                       | `NERDCTL_BRIDGE_IP`      | IP address for the default nerdctl bridge network, e.g., 10.1.100.1/24                                                                                           | Since 2.1.0      |
 
 The properties are parsed in the following precedence:
 1. CLI flag

pkg/cmd/compose/compose.go

@@ -65,7 +65,7 @@ func New(client *containerd.Client, globalOptions types.GlobalCommandOptions, op
 		return nil, err
 	}
 
-	cniEnv, err := netutil.NewCNIEnv(globalOptions.CNIPath, globalOptions.CNINetConfPath, netutil.WithNamespace(globalOptions.Namespace), netutil.WithDefaultNetwork())
+	cniEnv, err := netutil.NewCNIEnv(globalOptions.CNIPath, globalOptions.CNINetConfPath, netutil.WithNamespace(globalOptions.Namespace), netutil.WithDefaultNetwork(globalOptions.BridgeIP))
 	if err != nil {
 		return nil, err
 	}

pkg/cmd/container/kill.go

@@ -154,7 +154,7 @@ func cleanupNetwork(ctx context.Context, container containerd.Container, globalO
 		case nettype.Host, nettype.None, nettype.Container, nettype.Namespace:
 			// NOP
 		case nettype.CNI:
-			e, err := netutil.NewCNIEnv(globalOpts.CNIPath, globalOpts.CNINetConfPath, netutil.WithNamespace(globalOpts.Namespace), netutil.WithDefaultNetwork())
+			e, err := netutil.NewCNIEnv(globalOpts.CNIPath, globalOpts.CNINetConfPath, netutil.WithNamespace(globalOpts.Namespace), netutil.WithDefaultNetwork(globalOpts.BridgeIP))
 			if err != nil {
 				return err
 			}

pkg/config/config.go

@@ -39,6 +39,7 @@ type Config struct {
 	HostsDir         []string `toml:"hosts_dir"`
 	Experimental     bool     `toml:"experimental"`
 	HostGatewayIP    string   `toml:"host_gateway_ip"`
+	BridgeIP         string   `toml:"bridge_ip, omitempty"`
 }
 
 // New creates a default Config object statically,

pkg/containerutil/container_network_manager_linux.go

@@ -40,7 +40,7 @@ type cniNetworkManagerPlatform struct {
 
 // Verifies that the internal network settings are correct.
 func (m *cniNetworkManager) VerifyNetworkOptions(_ context.Context) error {
-	e, err := netutil.NewCNIEnv(m.globalOptions.CNIPath, m.globalOptions.CNINetConfPath, netutil.WithNamespace(m.globalOptions.Namespace), netutil.WithDefaultNetwork())
+	e, err := netutil.NewCNIEnv(m.globalOptions.CNIPath, m.globalOptions.CNINetConfPath, netutil.WithNamespace(m.globalOptions.Namespace), netutil.WithDefaultNetwork(m.globalOptions.BridgeIP))
 	if err != nil {
 		return err
 	}

pkg/containerutil/container_network_manager_windows.go

@@ -36,7 +36,7 @@ type cniNetworkManagerPlatform struct {
 
 // Verifies that the internal network settings are correct.
 func (m *cniNetworkManager) VerifyNetworkOptions(_ context.Context) error {
-	e, err := netutil.NewCNIEnv(m.globalOptions.CNIPath, m.globalOptions.CNINetConfPath, netutil.WithNamespace(m.globalOptions.Namespace), netutil.WithDefaultNetwork())
+	e, err := netutil.NewCNIEnv(m.globalOptions.CNIPath, m.globalOptions.CNINetConfPath, netutil.WithNamespace(m.globalOptions.Namespace), netutil.WithDefaultNetwork(m.globalOptions.BridgeIP))
 	if err != nil {
 		return err
 	}
@@ -67,7 +67,7 @@ func (m *cniNetworkManager) VerifyNetworkOptions(_ context.Context) error {
 }
 
 func (m *cniNetworkManager) getCNI() (gocni.CNI, error) {
-	e, err := netutil.NewCNIEnv(m.globalOptions.CNIPath, m.globalOptions.CNINetConfPath, netutil.WithNamespace(m.globalOptions.Namespace), netutil.WithDefaultNetwork())
+	e, err := netutil.NewCNIEnv(m.globalOptions.CNIPath, m.globalOptions.CNINetConfPath, netutil.WithNamespace(m.globalOptions.Namespace), netutil.WithDefaultNetwork(m.globalOptions.BridgeIP))
 	if err != nil {
 		return nil, fmt.Errorf("failed to instantiate CNI env: %s", err)
 	}

pkg/netutil/netutil.go

@@ -180,9 +180,9 @@ func namespaceUsedNetworks(ctx context.Context, containers []containerd.Containe
 	return used, nil
 }
 
-func WithDefaultNetwork() CNIEnvOpt {
+func WithDefaultNetwork(bridgeIP string) CNIEnvOpt {
 	return func(e *CNIEnv) error {
-		return e.ensureDefaultNetworkConfig()
+		return e.ensureDefaultNetworkConfig(bridgeIP)
 	}
 }
 
@@ -323,7 +323,6 @@ func (e *CNIEnv) CreateNetwork(opts types.NetworkCreateOptions) (*NetworkConfig,
 		if _, ok := netMap[opts.Name]; ok {
 			return errdefs.ErrAlreadyExists
 		}
-
 		ipam, err := e.generateIPAM(opts.IPAMDriver, opts.Subnets, opts.Gateway, opts.IPRange, opts.IPAMOptions, opts.IPv6)
 		if err != nil {
 			return err
@@ -406,31 +405,44 @@ func (e *CNIEnv) GetDefaultNetworkConfig() (*NetworkConfig, error) {
 	return nil, nil
 }
 
-func (e *CNIEnv) ensureDefaultNetworkConfig() error {
+func (e *CNIEnv) ensureDefaultNetworkConfig(bridgeIP string) error {
 	defaultNet, err := e.GetDefaultNetworkConfig()
 	if err != nil {
 		return fmt.Errorf("failed to check for default network: %s", err)
 	}
 	if defaultNet == nil {
-		if err := e.createDefaultNetworkConfig(); err != nil {
+		if err := e.createDefaultNetworkConfig(bridgeIP); err != nil {
 			return fmt.Errorf("failed to create default network: %s", err)
 		}
 	}
 	return nil
 }
 
-func (e *CNIEnv) createDefaultNetworkConfig() error {
+func (e *CNIEnv) createDefaultNetworkConfig(bridgeIP string) error {
 	filename := e.getConfigPathForNetworkName(DefaultNetworkName)
 	if _, err := os.Stat(filename); err == nil {
 		return fmt.Errorf("already found existing network config at %q, cannot create new network named %q", filename, DefaultNetworkName)
 	}
+
+	bridgeCIDR := DefaultCIDR
+	bridgeGatewayIP := ""
+	if bridgeIP != "" {
+		bIP, bCIDR, err := net.ParseCIDR(bridgeIP)
+		if err != nil {
+			return fmt.Errorf("invalid bridge ip %s: %s", bridgeIP, err)
+		}
+		bridgeGatewayIP = bIP.String()
+		bridgeCIDR = bCIDR.String()
+	}
 	opts := types.NetworkCreateOptions{
 		Name:       DefaultNetworkName,
 		Driver:     DefaultNetworkName,
-		Subnets:    []string{DefaultCIDR},
+		Subnets:    []string{bridgeCIDR},
+		Gateway:    bridgeGatewayIP,
 		IPAMDriver: "default",
 		Labels:     []string{fmt.Sprintf("%s=true", labels.NerdctlDefaultNetwork)},
 	}
+
 	_, err := e.CreateNetwork(opts)
 	if err != nil && !errdefs.IsAlreadyExists(err) {
 		return err

pkg/netutil/netutil_linux_test.go

@@ -30,4 +30,5 @@ func TestDefaultNetworkCreation(t *testing.T) {
 	}
 
 	testDefaultNetworkCreation(t)
+	testDefaultNetworkCreationWithBridgeIP(t)
 }

pkg/netutil/netutil_test.go

@@ -18,6 +18,7 @@ package netutil
 
 import (
 	"bytes"
+	"encoding/json"
 	"fmt"
 	"net"
 	"os"
@@ -33,6 +34,8 @@ import (
 	"github.com/containerd/nerdctl/v2/pkg/testutil"
 )
 
+const testBridgeIP = "10.1.100.1/24" // nolint:unused
+
 const preExistingNetworkConfigTemplate = `
 {
     "cniVersion": "0.2.0",
@@ -160,10 +163,77 @@ func testDefaultNetworkCreation(t *testing.T) {
 	assert.Assert(t, defaultNetConf == nil)
 
 	// Attempt to create the default network.
-	err = cniEnv.ensureDefaultNetworkConfig()
+	err = cniEnv.ensureDefaultNetworkConfig("")
+	assert.NilError(t, err)
+
+	// Ensure default network config is present now.
+	defaultNetConf, err = cniEnv.GetDefaultNetworkConfig()
+	assert.NilError(t, err)
+	assert.Assert(t, defaultNetConf != nil)
+
+	// Check network config file present.
+	stat, err := os.Stat(defaultNetConf.File)
+	assert.NilError(t, err)
+	firstConfigModTime := stat.ModTime()
+
+	// Check default network label present.
+	assert.Assert(t, defaultNetConf.NerdctlLabels != nil)
+	lstr, ok := (*defaultNetConf.NerdctlLabels)[labels.NerdctlDefaultNetwork]
+	assert.Assert(t, ok)
+	boolv, err := strconv.ParseBool(lstr)
+	assert.NilError(t, err)
+	assert.Assert(t, boolv)
+
+	// Ensure network isn't created twice or accidentally re-created.
+	err = cniEnv.ensureDefaultNetworkConfig("")
+	assert.NilError(t, err)
+
+	// Check for any other network config files.
+	files := []os.FileInfo{}
+	walkF := func(p string, info os.FileInfo, err error) error {
+		files = append(files, info)
+		return nil
+	}
+	err = filepath.Walk(cniConfTestDir, walkF)
+	assert.NilError(t, err)
+	assert.Assert(t, len(files) == 2) // files[0] is the entry for '.'
+	assert.Assert(t, filepath.Join(cniConfTestDir, files[1].Name()) == defaultNetConf.File)
+	assert.Assert(t, firstConfigModTime == files[1].ModTime())
+}
+
+// Tests whether nerdctl properly creates the default network
+// with a custom bridge IP and subnet.
+// nolint:unused
+func testDefaultNetworkCreationWithBridgeIP(t *testing.T) {
+	// To prevent subnet collisions when attempting to recreate the default network
+	// in the isolated CNI config dir we'll be using, we must first delete
+	// the network in the default CNI config dir.
+	defaultCniEnv := CNIEnv{
+		Path:        ncdefaults.CNIPath(),
+		NetconfPath: ncdefaults.CNINetConfPath(),
+	}
+	defaultNet, err := defaultCniEnv.GetDefaultNetworkConfig()
 	assert.NilError(t, err)
+	if defaultNet != nil {
+		assert.NilError(t, defaultCniEnv.RemoveNetwork(defaultNet))
+	}
 
-	// Ensure no default network config is present now.
+	// We create a tempdir for the CNI conf path to ensure an empty env for this test.
+	cniConfTestDir := t.TempDir()
+	cniEnv := CNIEnv{
+		Path:        ncdefaults.CNIPath(),
+		NetconfPath: cniConfTestDir,
+	}
+	// Ensure no default network config is not present.
+	defaultNetConf, err := cniEnv.GetDefaultNetworkConfig()
+	assert.NilError(t, err)
+	assert.Assert(t, defaultNetConf == nil)
+
+	// Attempt to create the default network with a test bridgeIP
+	err = cniEnv.ensureDefaultNetworkConfig(testBridgeIP)
+	assert.NilError(t, err)
+
+	// Ensure default network config is present now.
 	defaultNetConf, err = cniEnv.GetDefaultNetworkConfig()
 	assert.NilError(t, err)
 	assert.Assert(t, defaultNetConf != nil)
@@ -181,8 +251,40 @@ func testDefaultNetworkCreation(t *testing.T) {
 	assert.NilError(t, err)
 	assert.Assert(t, boolv)
 
+	// Check bridge IP is set.
+	assert.Assert(t, defaultNetConf.Plugins != nil)
+	assert.Assert(t, len(defaultNetConf.Plugins) > 0)
+	bridgePlugin := defaultNetConf.Plugins[0]
+	var bridgeConfig struct {
+		Type   string `json:"type"`
+		Bridge string `json:"bridge"`
+		IPAM   struct {
+			Ranges [][]struct {
+				Gateway string `json:"gateway"`
+				Subnet  string `json:"subnet"`
+			} `json:"ranges"`
+			Routes []struct {
+				Dst string `json:"dst"`
+			} `json:"routes"`
+			Type string `json:"type"`
+		} `json:"ipam"`
+	}
+
+	err = json.Unmarshal(bridgePlugin.Bytes, &bridgeConfig)
+	if err != nil {
+		t.Fatalf("Failed to parse bridge plugin config: %v", err)
+	}
+
+	// Assert on bridge plugin configuration
+	assert.Equal(t, "bridge", bridgeConfig.Type)
+	// Assert on IPAM configuration
+	assert.Equal(t, "10.1.100.1", bridgeConfig.IPAM.Ranges[0][0].Gateway)
+	assert.Equal(t, "10.1.100.0/24", bridgeConfig.IPAM.Ranges[0][0].Subnet)
+	assert.Equal(t, "0.0.0.0/0", bridgeConfig.IPAM.Routes[0].Dst)
+	assert.Equal(t, "host-local", bridgeConfig.IPAM.Type)
+
 	// Ensure network isn't created twice or accidentally re-created.
-	err = cniEnv.ensureDefaultNetworkConfig()
+	err = cniEnv.ensureDefaultNetworkConfig(testBridgeIP)
 	assert.NilError(t, err)
 
 	// Check for any other network config files.
@@ -249,7 +351,7 @@ func TestNetworkWithDefaultNameAlreadyExists(t *testing.T) {
 	assert.Assert(t, defaultNetConf != nil)
 	assert.Assert(t, defaultNetConf.File == testConfFile)
 
-	err = cniEnv.ensureDefaultNetworkConfig()
+	err = cniEnv.ensureDefaultNetworkConfig("")
 	assert.NilError(t, err)
 
 	netConfs, err = cniEnv.NetworkList()

pkg/ocihook/ocihook.go

@@ -61,7 +61,7 @@ const (
 	NetworkNamespace = labels.Prefix + "network-namespace"
 )
 
-func Run(stdin io.Reader, stderr io.Writer, event, dataStore, cniPath, cniNetconfPath string) error {
+func Run(stdin io.Reader, stderr io.Writer, event, dataStore, cniPath, cniNetconfPath, bridgeIP string) error {
 	if stdin == nil || event == "" || dataStore == "" || cniPath == "" || cniNetconfPath == "" {
 		return errors.New("got insufficient args")
 	}
@@ -113,7 +113,7 @@ func Run(stdin io.Reader, stderr io.Writer, event, dataStore, cniPath, cniNetcon
 	}
 	defer lockutil.Unlock(lock)
 
-	opts, err := newHandlerOpts(&state, dataStore, cniPath, cniNetconfPath)
+	opts, err := newHandlerOpts(&state, dataStore, cniPath, cniNetconfPath, bridgeIP)
 	if err != nil {
 		return err
 	}
@@ -128,7 +128,7 @@ func Run(stdin io.Reader, stderr io.Writer, event, dataStore, cniPath, cniNetcon
 	}
 }
 
-func newHandlerOpts(state *specs.State, dataStore, cniPath, cniNetconfPath string) (*handlerOpts, error) {
+func newHandlerOpts(state *specs.State, dataStore, cniPath, cniNetconfPath, bridgeIP string) (*handlerOpts, error) {
 	o := &handlerOpts{
 		state:     state,
 		dataStore: dataStore,
@@ -173,7 +173,7 @@ func newHandlerOpts(state *specs.State, dataStore, cniPath, cniNetconfPath strin
 	case nettype.Host, nettype.None, nettype.Container, nettype.Namespace:
 		// NOP
 	case nettype.CNI:
-		e, err := netutil.NewCNIEnv(cniPath, cniNetconfPath, netutil.WithNamespace(namespace), netutil.WithDefaultNetwork())
+		e, err := netutil.NewCNIEnv(cniPath, cniNetconfPath, netutil.WithNamespace(namespace), netutil.WithDefaultNetwork(bridgeIP))
 		if err != nil {
 			return nil, err
 		}