libnetwork/netavark: add plugin support

Users can now suplly custom network drivers which will execute the
netavark plugin to create the network. Netavark will execute the pluign
to setup/teardown the netns.
see https://github.com/containers/netavark/pull/509

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

common/libnetwork/netavark/config.go

@@ -209,7 +209,11 @@ func (n *netavarkNetwork) networkCreate(newNetwork *types.Network, defaultNet bo
 			return nil, err
 		}
 	default:
-		return nil, fmt.Errorf("unsupported driver %s: %w", newNetwork.Driver, types.ErrInvalidArg)
+		net, err := n.createPlugin(newNetwork)
+		if err != nil {
+			return nil, err
+		}
+		newNetwork = net
 	}
 
 	// when we do not have ipam we must disable dns
@@ -403,3 +407,55 @@ func validateIPAMDriver(n *types.Network) error {
 	}
 	return nil
 }
+
+var errInvalidPluginResult = errors.New("invalid plugin result")
+
+func (n *netavarkNetwork) createPlugin(net *types.Network) (*types.Network, error) {
+	path, err := getPlugin(net.Driver, n.pluginDirs)
+	if err != nil {
+		return nil, err
+	}
+	result := new(types.Network)
+	err = n.execPlugin(path, []string{"create"}, net, result)
+	if err != nil {
+		return nil, fmt.Errorf("plugin %s failed: %w", path, err)
+	}
+	// now make sure that neither the name, ID, driver were changed by the plugin
+	if net.Name != result.Name {
+		return nil, fmt.Errorf("%w: changed network name", errInvalidPluginResult)
+	}
+	if net.ID != result.ID {
+		return nil, fmt.Errorf("%w: changed network ID", errInvalidPluginResult)
+	}
+	if net.Driver != result.Driver {
+		return nil, fmt.Errorf("%w: changed network driver", errInvalidPluginResult)
+	}
+	return result, nil
+}
+
+func getAllPlugins(dirs []string) []string {
+	var plugins []string
+	for _, dir := range dirs {
+		entries, err := os.ReadDir(dir)
+		if err == nil {
+			for _, entry := range entries {
+				name := entry.Name()
+				if !util.StringInSlice(name, plugins) {
+					plugins = append(plugins, name)
+				}
+			}
+		}
+	}
+	return plugins
+}
+
+func getPlugin(name string, dirs []string) (string, error) {
+	for _, dir := range dirs {
+		fullpath := filepath.Join(dir, name)
+		st, err := os.Stat(fullpath)
+		if err == nil && st.Mode().IsRegular() {
+			return fullpath, nil
+		}
+	}
+	return "", fmt.Errorf("failed to find driver or plugin %q", name)
+}

common/libnetwork/netavark/config_test.go

@@ -925,7 +925,7 @@ var _ = Describe("Config", func() {
 			}
 			_, err := libpodNet.NetworkCreate(network, nil)
 			Expect(err).To(HaveOccurred())
-			Expect(err.Error()).To(ContainSubstring("unsupported driver someDriver"))
+			Expect(err.Error()).To(ContainSubstring(`failed to find driver or plugin "someDriver"`))
 		})
 
 		It("network create internal and dns", func() {

common/libnetwork/netavark/exec.go

@@ -77,6 +77,23 @@ func getRustLogEnv() string {
 // All errors return by this function should be of the type netavarkError
 // to provide a helpful error message.
 func (n *netavarkNetwork) execNetavark(args []string, stdin, result interface{}) error {
+	// set the netavark log level to the same as the podman
+	env := append(os.Environ(), getRustLogEnv())
+	// if we run with debug log level lets also set RUST_BACKTRACE=1 so we can get the full stack trace in case of panics
+	if logrus.IsLevelEnabled(logrus.DebugLevel) {
+		env = append(env, "RUST_BACKTRACE=1")
+	}
+	if n.dnsBindPort != 0 {
+		env = append(env, "NETAVARK_DNS_PORT="+strconv.Itoa(int(n.dnsBindPort)))
+	}
+	return n.execBinary(n.netavarkBinary, append(n.getCommonNetavarkOptions(), args...), stdin, result, env)
+}
+
+func (n *netavarkNetwork) execPlugin(path string, args []string, stdin, result interface{}) error {
+	return n.execBinary(path, args, stdin, result, nil)
+}
+
+func (n *netavarkNetwork) execBinary(path string, args []string, stdin, result interface{}, env []string) error {
 	stdinR, stdinW, err := os.Pipe()
 	if err != nil {
 		return newNetavarkError("failed to create stdin pipe", err)
@@ -108,20 +125,12 @@ func (n *netavarkNetwork) execNetavark(args []string, stdin, result interface{})
 		logWriter = io.MultiWriter(logWriter, &logrusNetavarkWriter{})
 	}
 
-	cmd := exec.Command(n.netavarkBinary, append(n.getCommonNetavarkOptions(), args...)...)
+	cmd := exec.Command(path, args...)
 	// connect the pipes to stdin and stdout
 	cmd.Stdin = stdinR
 	cmd.Stdout = stdoutW
 	cmd.Stderr = logWriter
-	// set the netavark log level to the same as the podman
-	cmd.Env = append(os.Environ(), getRustLogEnv())
-	// if we run with debug log level lets also set RUST_BACKTRACE=1 so we can get the full stack trace in case of panics
-	if logrus.IsLevelEnabled(logrus.DebugLevel) {
-		cmd.Env = append(cmd.Env, "RUST_BACKTRACE=1")
-	}
-	if n.dnsBindPort != 0 {
-		cmd.Env = append(cmd.Env, "NETAVARK_DNS_PORT="+strconv.Itoa(int(n.dnsBindPort)))
-	}
+	cmd.Env = env
 
 	err = cmd.Start()
 	if err != nil {

common/libnetwork/netavark/network.go

@@ -46,6 +46,9 @@ type netavarkNetwork struct {
 	// dnsBindPort is set the the port to pass to netavark for aardvark
 	dnsBindPort uint16
 
+	// pluginDirs list of directories were netavark plugins are located
+	pluginDirs []string
+
 	// ipamDBPath is the path to the ip allocation bolt db
 	ipamDBPath string
 
@@ -86,6 +89,9 @@ type InitConfig struct {
 	// DNSBindPort is set the the port to pass to netavark for aardvark
 	DNSBindPort uint16
 
+	// PluginDirs list of directories were netavark plugins are located
+	PluginDirs []string
+
 	// Syslog describes whenever the netavark debbug output should be log to the syslog as well.
 	// This will use logrus to do so, make sure logrus is set up to log to the syslog.
 	Syslog bool
@@ -143,6 +149,7 @@ func NewNetworkInterface(conf *InitConfig) (types.ContainerNetwork, error) {
 		defaultSubnet:      defaultNet,
 		defaultsubnetPools: defaultSubnetPools,
 		dnsBindPort:        conf.DNSBindPort,
+		pluginDirs:         conf.PluginDirs,
 		lock:               lock,
 		syslog:             conf.Syslog,
 	}
@@ -153,7 +160,8 @@ func NewNetworkInterface(conf *InitConfig) (types.ContainerNetwork, error) {
 // Drivers will return the list of supported network drivers
 // for this interface.
 func (n *netavarkNetwork) Drivers() []string {
-	return []string{types.BridgeNetworkDriver, types.MacVLANNetworkDriver}
+	paths := getAllPlugins(n.pluginDirs)
+	return append([]string{types.BridgeNetworkDriver, types.MacVLANNetworkDriver}, paths...)
 }
 
 // DefaultNetworkName will return the default netavark network name.