fix: use annotation for MirageOS net device name

pkg/unikontainers/config.go

@@ -45,6 +45,7 @@ const (
 	annotBlock         = "com.urunc.unikernel.block"
 	annotBlockMntPoint = "com.urunc.unikernel.blkMntPoint"
 	annotMountRootfs   = "com.urunc.unikernel.mountRootfs"
+	annotNetDev        = "com.urunc.unikernel.netDev"
 )
 
 // A UnikernelConfig struct holds the info provided by bima image on how to execute our unikernel
@@ -58,6 +59,7 @@ type UnikernelConfig struct {
 	Block            string `json:"com.urunc.unikernel.block,omitempty"`
 	BlkMntPoint      string `json:"com.urunc.unikernel.blkMntPoint,omitempty"`
 	MountRootfs      string `json:"com.urunc.unikernel.mountRootfs"`
+	NetDev           string `json:"com.urunc.unikernel.netDev,omitempty"`
 }
 
 // validate checks if the mandatory configuration fields are present.
@@ -127,6 +129,7 @@ func getConfigFromSpec(spec *specs.Spec) *UnikernelConfig {
 	block := spec.Annotations[annotBlock]
 	blkMntPoint := spec.Annotations[annotBlockMntPoint]
 	MountRootfs := spec.Annotations[annotMountRootfs]
+	netDev := spec.Annotations[annotNetDev]
 	uniklog.WithFields(logrus.Fields{
 		"unikernelType":    tryDecode(unikernelType),
 		"unikernelVersion": tryDecode(unikernelVersion),
@@ -137,6 +140,7 @@ func getConfigFromSpec(spec *specs.Spec) *UnikernelConfig {
 		"block":            tryDecode(block),
 		"blkMntPoint":      tryDecode(blkMntPoint),
 		"mountRootfs":      tryDecode(MountRootfs),
+		"netDev":           tryDecode(netDev),
 	}).WithField("source", "spec").Debug("urunc annotations")
 
 	return &UnikernelConfig{
@@ -149,6 +153,7 @@ func getConfigFromSpec(spec *specs.Spec) *UnikernelConfig {
 		Block:            block,
 		BlkMntPoint:      blkMntPoint,
 		MountRootfs:      MountRootfs,
+		NetDev:           netDev,
 	}
 }
 
@@ -188,6 +193,7 @@ func getConfigFromJSON(jsonFilePath string) (*UnikernelConfig, error) {
 		"block":            tryDecode(conf.Block),
 		"blkMntPoint":      tryDecode(conf.BlkMntPoint),
 		"mountRootfs":      tryDecode(conf.MountRootfs),
+		"netDev":           tryDecode(conf.NetDev),
 	}).WithField("source", uruncJSONFilename).Debug("urunc annotations")
 
 	return &conf, nil
@@ -258,6 +264,12 @@ func (c *UnikernelConfig) decode() error {
 	}
 	c.MountRootfs = string(decoded)
 
+	decoded, err = base64.StdEncoding.DecodeString(c.NetDev)
+	if err != nil {
+		return fmt.Errorf("failed to decode netDev: %v", err)
+	}
+	c.NetDev = string(decoded)
+
 	return nil
 }
 
@@ -291,6 +303,9 @@ func (c *UnikernelConfig) Map() map[string]string {
 	if c.MountRootfs != "" {
 		myMap[annotMountRootfs] = c.MountRootfs
 	}
+	if c.NetDev != "" {
+		myMap[annotNetDev] = c.NetDev
+	}
 
 	return myMap
 }

pkg/unikontainers/config_test.go

@@ -38,6 +38,7 @@ func TestGetConfigFromSpec(t *testing.T) {
 				annotBlock:         "block1",
 				annotBlockMntPoint: "point1",
 				annotMountRootfs:   "true",
+				annotNetDev:        "mynetdev",
 			},
 		}
 
@@ -50,6 +51,7 @@ func TestGetConfigFromSpec(t *testing.T) {
 			Block:           "block1",
 			BlkMntPoint:     "point1",
 			MountRootfs:     "true",
+			NetDev:          "mynetdev",
 		}
 
 		config := getConfigFromSpec(spec)
@@ -239,6 +241,7 @@ func TestMap(t *testing.T) {
 			Block:           "block_value",
 			BlkMntPoint:     "point_value",
 			MountRootfs:     "false",
+			NetDev:          "netdev_value",
 		}
 		expectedMap := map[string]string{
 			annotCmdLine:       "cmd_value",
@@ -249,6 +252,7 @@ func TestMap(t *testing.T) {
 			annotBlock:         "block_value",
 			annotBlockMntPoint: "point_value",
 			annotMountRootfs:   "false",
+			annotNetDev:        "netdev_value",
 		}
 		resultMap := config.Map()
 		assert.Equal(t, expectedMap, resultMap)

pkg/unikontainers/types/types.go

@@ -86,6 +86,7 @@ type UnikernelParams struct {
 	Monitor    string   // The monitor where guest will execute
 	Version    string   // The version of the unikernel
 	InitrdPath string   // The path to the initrd of the unikernel
+	NetDevName string   // The name of the guest network device declared at build time
 	Net        NetDevParams
 	Block      []BlockDevParams
 	Rootfs     RootfsParams  // Information about rootfs

pkg/unikontainers/unikernels/mirage.go

@@ -24,10 +24,11 @@ import (
 const MirageUnikernel string = "mirage"
 
 type Mirage struct {
-	Command string
-	Monitor string
-	Net     MirageNet
-	Block   []MirageBlock
+	Command    string
+	Monitor    string
+	Net        MirageNet
+	Block      []MirageBlock
+	netDevName string
 }
 
 type MirageNet struct {
@@ -57,8 +58,9 @@ func (m *Mirage) SupportsFS(_ string) bool {
 func (m *Mirage) MonitorNetCli(ifName string, mac string) string {
 	switch m.Monitor {
 	case "hvt", "spt":
-		netOption := "--net:service=" + ifName
-		netOption += " --net-mac:service=" + mac
+		name := m.netDevName
+		netOption := "--net:" + name + "=" + ifName
+		netOption += " --net-mac:" + name + "=" + mac
 		return netOption
 	default:
 		return ""
@@ -99,8 +101,13 @@ func (m *Mirage) MonitorCli() types.MonitorCliArgs {
 func (m *Mirage) Init(data types.UnikernelParams) error {
 	// if Mask is empty, there is no network support
 	if data.Net.Mask != "" {
-		m.Net.Address = "--ipv4=" + data.Net.IP + "/24"
-		m.Net.Gateway = "--ipv4-gateway=" + data.Net.Gateway
+		if data.NetDevName != "" && data.NetDevName != "service" {
+			m.Net.Address = "--" + data.NetDevName + "-ipv4=" + data.Net.IP + "/24"
+			m.Net.Gateway = "--" + data.NetDevName + "-ipv4-gateway=" + data.Net.Gateway
+		} else {
+			m.Net.Address = "--ipv4=" + data.Net.IP + "/24"
+			m.Net.Gateway = "--ipv4-gateway=" + data.Net.Gateway
+		}
 	}
 	m.Block = make([]MirageBlock, 0, len(data.Block))
 	for _, blk := range data.Block {
@@ -114,6 +121,12 @@ func (m *Mirage) Init(data types.UnikernelParams) error {
 	m.Command = strings.Join(data.CmdLine, " ")
 	m.Monitor = data.Monitor
 
+	if data.NetDevName != "" {
+		m.netDevName = data.NetDevName
+	} else {
+		m.netDevName = "service"
+	}
+
 	return nil
 }
 

pkg/unikontainers/unikernels/mirage_test.go

@@ -0,0 +1,44 @@
+// Copyright (c) 2023-2026, Nubificus LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package unikernels
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/urunc-dev/urunc/pkg/unikontainers/types"
+)
+
+func TestMirageNetDevName(t *testing.T) {
+	t.Run("uses net device name from annotation", func(t *testing.T) {
+		t.Parallel()
+		m := &Mirage{}
+		err := m.Init(types.UnikernelParams{Monitor: "hvt", NetDevName: "mynetdev"})
+		assert.NoError(t, err)
+		cli := m.MonitorNetCli("tap0", "aa:bb:cc:dd:ee:ff")
+		assert.Contains(t, cli, "--net:mynetdev=tap0")
+		assert.Contains(t, cli, "--net-mac:mynetdev=aa:bb:cc:dd:ee:ff")
+	})
+
+	t.Run("falls back to service when annotation is absent", func(t *testing.T) {
+		t.Parallel()
+		m := &Mirage{}
+		err := m.Init(types.UnikernelParams{Monitor: "hvt"})
+		assert.NoError(t, err)
+		cli := m.MonitorNetCli("tap0", "aa:bb:cc:dd:ee:ff")
+		assert.Contains(t, cli, "--net:service=tap0")
+		assert.Contains(t, cli, "--net-mac:service=aa:bb:cc:dd:ee:ff")
+	})
+}

pkg/unikontainers/unikontainers.go

@@ -380,11 +380,12 @@ func (u *Unikontainer) Exec(metrics m.Writer) error {
 	// UnikernelParams
 	// populate unikernel params
 	unikernelParams := types.UnikernelParams{
-		CmdLine:  u.Spec.Process.Args,
-		EnvVars:  u.Spec.Process.Env,
-		Monitor:  vmmType,
-		Version:  unikernelVersion,
-		ProcConf: procAttrs,
+		CmdLine:    u.Spec.Process.Args,
+		EnvVars:    u.Spec.Process.Env,
+		Monitor:    vmmType,
+		Version:    unikernelVersion,
+		ProcConf:   procAttrs,
+		NetDevName: u.State.Annotations[annotNetDev],
 	}
 	if len(unikernelParams.CmdLine) == 0 {
 		unikernelParams.CmdLine = strings.Fields(u.State.Annotations[annotCmdLine])