f-33: vm: start vms with multiple nic

Signed-off-by: GnomeZworc <nicolas.boufidjeline@g3e.fr>

api/agent.yaml

@@ -448,6 +448,12 @@ components:
         interfaces:
           type: array
           minItems: 1
+          description: >
+            Network interfaces, in order. The position determines the PCI slot
+            (0x03 + index) and therefore the interface name inside the guest.
+            **Exactly one** interface must be marked primary: it carries the
+            default route and the metadata server. All subnets must belong to
+            the same VPC.
           items:
             $ref: "#/components/schemas/VMInterface"
         storage:

cmd/agent/main.go

@@ -53,6 +53,11 @@ func main() {
 		return
 	}
 
+	if err := migration.MigrateVMNICs(db, log.With(slog.String("component", "migration"))); err != nil {
+		log.Error("vm nic migration failed", "error", err)
+		return
+	}
+
 	q := worker.New(cfg.Worker.BufferSize)
 	q.Start(cfg.Worker.Count)
 

internal/api/agent/vm.go

@@ -3,6 +3,7 @@ package agentapi
 import (
 	"encoding/json"
 	"net/http"
+	"sort"
 	"strconv"
 	"strings"
 
@@ -71,6 +72,52 @@ func (s *Server) stopVM(w http.ResponseWriter, _ *http.Request, name string) {
 	json.NewEncoder(w).Encode(vm)
 }
 
+// interfacesFromDB reconstruit les interfaces depuis vm/<name>/nic/<index>/…,
+// triées par index — celui-ci détermine le slot PCI, donc le nom de l'interface
+// dans le guest.
+func interfacesFromDB(prefix string, entries map[string]string) []VMInterface {
+	nicPrefix := prefix + "nic/"
+	byIndex := make(map[int]*VMInterface)
+
+	for key, value := range entries {
+		rest := strings.TrimPrefix(key, nicPrefix)
+		if rest == key {
+			continue
+		}
+		parts := strings.Split(rest, "/")
+		if len(parts) != 2 {
+			continue
+		}
+		idx, err := strconv.Atoi(parts[0])
+		if err != nil {
+			continue
+		}
+		if byIndex[idx] == nil {
+			byIndex[idx] = &VMInterface{}
+		}
+		switch parts[1] {
+		case "subnet":
+			byIndex[idx].Subnet = value
+		case "ip":
+			byIndex[idx].IP = value
+		case "primary":
+			byIndex[idx].Primary = value == "true"
+		}
+	}
+
+	indexes := make([]int, 0, len(byIndex))
+	for idx := range byIndex {
+		indexes = append(indexes, idx)
+	}
+	sort.Ints(indexes)
+
+	ifaces := make([]VMInterface, 0, len(indexes))
+	for _, idx := range indexes {
+		ifaces = append(ifaces, *byIndex[idx])
+	}
+	return ifaces
+}
+
 func vmFromDB(name string, entries map[string]string) (VM, error) {
 	prefix := "vm/" + name + "/"
 	vm := VM{Name: name}
@@ -81,11 +128,7 @@ func vmFromDB(name string, entries map[string]string) (VM, error) {
 	vm.CPUs, _ = strconv.Atoi(entries[prefix+"cpus"])
 	vm.UEFI = entries[prefix+"uefi"] == "true"
 
-	subnet := entries[prefix+"subnet"]
-	ip := entries[prefix+"ip"]
-	if subnet != "" || ip != "" {
-		vm.Interfaces = []VMInterface{{Subnet: subnet, IP: ip, Primary: true}}
-	}
+	vm.Interfaces = interfacesFromDB(prefix, entries)
 
 	diskPrefix := prefix + "disk/"
 	for key, path := range entries {

internal/api/agent/vm_test.go

@@ -262,3 +262,89 @@ func TestStartVM_EmptyBase64MeansNoDocument(t *testing.T) {
 		t.Errorf("un base64 vide est indiscernable d'un champ absent : %v", entries)
 	}
 }
+
+// --- interfaces multiples ---
+
+func TestVmFromDB_MultipleInterfacesSortedByIndex(t *testing.T) {
+	vm, err := vmFromDB("vm-multi", map[string]string{
+		"vm/vm-multi/state":         "running",
+		"vm/vm-multi/nic/1/subnet":  "sn-2",
+		"vm/vm-multi/nic/1/ip":      "10.2.0.5",
+		"vm/vm-multi/nic/0/subnet":  "sn-1",
+		"vm/vm-multi/nic/0/ip":      "10.1.0.5",
+		"vm/vm-multi/nic/0/primary": "true",
+		"vm/vm-multi/disk/vda":      "/data/root.qcow2",
+	})
+	if err != nil {
+		t.Fatalf("vmFromDB : %v", err)
+	}
+	if len(vm.Interfaces) != 2 {
+		t.Fatalf("2 interfaces attendues, obtenu %d : %+v", len(vm.Interfaces), vm.Interfaces)
+	}
+	if vm.Interfaces[0].Subnet != "sn-1" || !vm.Interfaces[0].Primary {
+		t.Errorf("la première doit être l'index 0, primaire : %+v", vm.Interfaces[0])
+	}
+	if vm.Interfaces[1].Subnet != "sn-2" || vm.Interfaces[1].Primary {
+		t.Errorf("la seconde doit être l'index 1, non primaire : %+v", vm.Interfaces[1])
+	}
+}
+
+func TestStartVM_StoresAllInterfaces(t *testing.T) {
+	s, db := newTestServer(t)
+	for _, sn := range []string{"sn-1", "sn-2"} {
+		kv.AddInDB(db, "subnet/"+sn+"/state", "running")
+		kv.AddInDB(db, "subnet/"+sn+"/vpc", "vpc-1")
+	}
+
+	body, _ := json.Marshal(VMCreateRequest{
+		Name: "vm-multi",
+		Interfaces: []VMInterface{
+			{Subnet: "sn-1", IP: "10.1.0.5", Primary: true},
+			{Subnet: "sn-2", IP: "10.2.0.5"},
+		},
+		Storage: []VMStorage{{Path: "/data/root.qcow2", Dev: "vda"}},
+	})
+
+	w := httptest.NewRecorder()
+	s.VmsHandler(w, httptest.NewRequest(http.MethodPost, "/vms", bytes.NewReader(body)))
+	if w.Code != http.StatusAccepted {
+		t.Fatalf("attendu 202, obtenu %d : %s", w.Code, w.Body.String())
+	}
+
+	if got, _ := kv.GetFromDB(db, "vm/vm-multi/nic/1/subnet"); got != "sn-2" {
+		t.Errorf("seconde interface non stockée : %q", got)
+	}
+	if got, _ := kv.GetFromDB(db, "vm/vm-multi/nic/0/primary"); got != "true" {
+		t.Errorf("primaire non marquée : %q", got)
+	}
+	if _, err := kv.GetFromDB(db, "vm/vm-multi/nic/1/primary"); err == nil {
+		t.Error("une interface non primaire ne doit pas porter la clé primary")
+	}
+}
+
+func TestStartVM_RejectsZeroOrTwoPrimaries(t *testing.T) {
+	cases := map[string][]VMInterface{
+		"aucune primaire": {{Subnet: "sn-1", IP: "10.1.0.5"}},
+		"deux primaires": {
+			{Subnet: "sn-1", IP: "10.1.0.5", Primary: true},
+			{Subnet: "sn-2", IP: "10.2.0.5", Primary: true},
+		},
+	}
+	for label, ifaces := range cases {
+		s, db := newTestServer(t)
+		for _, sn := range []string{"sn-1", "sn-2"} {
+			kv.AddInDB(db, "subnet/"+sn+"/state", "running")
+			kv.AddInDB(db, "subnet/"+sn+"/vpc", "vpc-1")
+		}
+		body, _ := json.Marshal(VMCreateRequest{
+			Name:       "vm-bad",
+			Interfaces: ifaces,
+			Storage:    []VMStorage{{Path: "/data/root.qcow2", Dev: "vda"}},
+		})
+		w := httptest.NewRecorder()
+		s.VmsHandler(w, httptest.NewRequest(http.MethodPost, "/vms", bytes.NewReader(body)))
+		if w.Code != http.StatusBadRequest {
+			t.Errorf("%s : attendu 400, obtenu %d — %s", label, w.Code, w.Body.String())
+		}
+	}
+}

internal/api/agent/vms.go

@@ -67,16 +67,17 @@ func (s *Server) startVM(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	var primary *VMInterface
-	for i := range req.Interfaces {
-		if req.Interfaces[i].Primary {
-			primary = &req.Interfaces[i]
-			break
+	nics := make([]dispatcher.VMNIC, len(req.Interfaces))
+	primaries := 0
+	for i, iface := range req.Interfaces {
+		nics[i] = dispatcher.VMNIC{Subnet: iface.Subnet, IP: iface.IP, Primary: iface.Primary}
+		if iface.Primary {
+			primaries++
 		}
 	}
-	if primary == nil {
+	if primaries != 1 {
 		w.WriteHeader(http.StatusBadRequest)
-		json.NewEncoder(w).Encode(ErrorResponse{Error: "one interface must be primary"})
+		json.NewEncoder(w).Encode(ErrorResponse{Error: "exactly one interface must be primary"})
 		return
 	}
 
@@ -94,8 +95,7 @@ func (s *Server) startVM(w http.ResponseWriter, r *http.Request) {
 
 	cmd := dispatcher.StartVMCommand{
 		Name:      req.Name,
-		Subnet:    primary.Subnet,
-		IP:        primary.IP,
+		NICs:      nics,
 		Disks:     disks,
 		Memory:    req.Memory,
 		CPUs:      req.CPUs,

internal/dhcp/reservation.go

@@ -10,6 +10,7 @@ import (
 type Reservation struct {
 	MAC string
 	IP  string
+	Tag string // pose set:<Tag> sur l'entrée, pour cibler les options par interface
 }
 
 func HostsDir(confDir, name string) string {
@@ -39,7 +40,11 @@ func WriteReservations(confDir, name, vmName string, res []Reservation) error {
 		if r.MAC == "" || r.IP == "" {
 			return fmt.Errorf("incomplete reservation for vm %q: mac=%q ip=%q", vmName, r.MAC, r.IP)
 		}
-		fmt.Fprintf(&sb, "%s,%s\n", r.MAC, r.IP)
+		if r.Tag == "" {
+			fmt.Fprintf(&sb, "%s,%s\n", r.MAC, r.IP)
+			continue
+		}
+		fmt.Fprintf(&sb, "%s,%s,set:%s\n", r.MAC, r.IP, r.Tag)
 	}
 
 	path := filepath.Join(dir, vmName)
@@ -49,6 +54,51 @@ func WriteReservations(confDir, name, vmName string, res []Reservation) error {
 	return nil
 }
 
+// WriteVMOptions écrit les options DHCP propres à des interfaces de cette VM
+// sur ce subnet : elles suppriment la route par défaut — option 3 nue — et
+// réémettent les autres routes.
+//
+// Un override de l'option 121 remplace la précédente en entier, il ne s'y
+// ajoute pas (vérifié sur dnsmasq 2.90) : omettre la route vers le serveur de
+// métadonnées la ferait disparaître, et la VM ne se provisionnerait pas.
+func WriteVMOptions(confDir, name, vmName string, tags []string, c Config) error {
+	if len(tags) == 0 {
+		return RemoveVMOptions(confDir, name, vmName)
+	}
+	if c.InterfaceIP == nil {
+		return fmt.Errorf("interface ip is required to build options for vm %q", vmName)
+	}
+	if c.DefaultGateway != nil {
+		return fmt.Errorf("vm options for %q must not carry a default route", vmName)
+	}
+
+	dir := OptsDir(confDir, name)
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return fmt.Errorf("create %s: %w", dir, err)
+	}
+
+	routes := strings.Join(classlessRoutes(c), ",")
+	var sb strings.Builder
+	for _, tag := range tags {
+		fmt.Fprintf(&sb, "tag:%s,3\n", tag)
+		fmt.Fprintf(&sb, "tag:%s,121,%s\n", tag, routes)
+	}
+
+	path := filepath.Join(dir, vmName)
+	if err := os.WriteFile(path, []byte(sb.String()), 0644); err != nil {
+		return fmt.Errorf("write %s: %w", path, err)
+	}
+	return nil
+}
+
+func RemoveVMOptions(confDir, name, vmName string) error {
+	path := filepath.Join(OptsDir(confDir, name), vmName)
+	if err := os.Remove(path); err != nil && !os.IsNotExist(err) {
+		return fmt.Errorf("remove %s: %w", path, err)
+	}
+	return nil
+}
+
 func RemoveReservations(confDir, name, vmName string) error {
 	for _, dir := range []string{HostsDir(confDir, name), OptsDir(confDir, name)} {
 		path := filepath.Join(dir, vmName)

internal/dhcp/reservation_test.go

@@ -1,8 +1,10 @@
 package dhcp
 
 import (
+	"net"
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 )
 
@@ -124,3 +126,103 @@ func TestUnitName(t *testing.T) {
 		t.Errorf("unit attendue dnsmasq@%s.service, obtenu %s", subName, got)
 	}
 }
+
+// --- options par interface ---
+
+func TestWriteReservations_WithTags(t *testing.T) {
+	dir := t.TempDir()
+	res := []Reservation{
+		{MAC: "00:22:33:00:01:02", IP: "10.1.1.2", Tag: "i-web-0"},
+		{MAC: "00:22:33:00:02:07", IP: "10.1.2.7", Tag: "i-web-1"},
+	}
+	if err := WriteReservations(dir, subName, "i-web", res); err != nil {
+		t.Fatalf("WriteReservations : %v", err)
+	}
+	content, _ := os.ReadFile(filepath.Join(HostsDir(dir, subName), "i-web"))
+	want := "00:22:33:00:01:02,10.1.1.2,set:i-web-0\n00:22:33:00:02:07,10.1.2.7,set:i-web-1\n"
+	if string(content) != want {
+		t.Errorf("attendu %q, obtenu %q", want, content)
+	}
+}
+
+func vmOptions(t *testing.T, dir string, tags []string, vpcRoute *net.IPNet) string {
+	t.Helper()
+	if err := WriteVMOptions(dir, subName, "i-web", tags, Config{
+		InterfaceIP: net.ParseIP("10.1.1.1").To4(),
+		VPCRoute:    vpcRoute,
+	}); err != nil {
+		t.Fatalf("WriteVMOptions : %v", err)
+	}
+	b, err := os.ReadFile(filepath.Join(OptsDir(dir, subName), "i-web"))
+	if err != nil {
+		return ""
+	}
+	return string(b)
+}
+
+func TestWriteVMOptions_SuppressesDefaultRoute(t *testing.T) {
+	_, vpcNet, _ := net.ParseCIDR("192.168.0.0/16")
+	got := vmOptions(t, t.TempDir(), []string{"i-web-1"}, vpcNet)
+
+	if !strings.Contains(got, "tag:i-web-1,3\n") {
+		t.Errorf("l'option 3 nue doit supprimer la route par défaut :\n%s", got)
+	}
+	if strings.Contains(got, "0.0.0.0/0") {
+		t.Errorf("la route par défaut ne doit pas figurer dans l'override :\n%s", got)
+	}
+}
+
+func TestWriteVMOptions_ReEmitsMetadataRoute(t *testing.T) {
+	_, vpcNet, _ := net.ParseCIDR("192.168.0.0/16")
+	got := vmOptions(t, t.TempDir(), []string{"i-web-1"}, vpcNet)
+
+	if !strings.Contains(got, "169.254.169.254/32,10.1.1.1") {
+		t.Errorf("un override de l'option 121 remplace la précédente en entier : sans la route metadata, la VM ne se provisionne pas\n%s", got)
+	}
+	if !strings.Contains(got, "192.168.0.0/16,10.1.1.1") {
+		t.Errorf("la route VPC doit être réémise elle aussi :\n%s", got)
+	}
+}
+
+func TestWriteVMOptions_BridgeHasNoVPCRoute(t *testing.T) {
+	got := vmOptions(t, t.TempDir(), []string{"i-web-1"}, nil)
+
+	if !strings.Contains(got, "169.254.169.254/32") {
+		t.Errorf("route metadata absente :\n%s", got)
+	}
+	if strings.Contains(got, "192.168") {
+		t.Errorf("aucune route VPC attendue en mode bridge :\n%s", got)
+	}
+}
+
+func TestWriteVMOptions_OneBlockPerTag(t *testing.T) {
+	got := vmOptions(t, t.TempDir(), []string{"i-web-1", "i-web-2"}, nil)
+
+	for _, tag := range []string{"tag:i-web-1,3", "tag:i-web-2,3"} {
+		if !strings.Contains(got, tag) {
+			t.Errorf("%q absent :\n%s", tag, got)
+		}
+	}
+}
+
+func TestWriteVMOptions_NoTagRemovesFile(t *testing.T) {
+	dir := t.TempDir()
+	_ = vmOptions(t, dir, []string{"i-web-1"}, nil)
+
+	if err := WriteVMOptions(dir, subName, "i-web", nil, Config{}); err != nil {
+		t.Fatalf("WriteVMOptions : %v", err)
+	}
+	if _, err := os.Stat(filepath.Join(OptsDir(dir, subName), "i-web")); !os.IsNotExist(err) {
+		t.Error("sans interface non primaire, aucun fichier d'options ne doit subsister")
+	}
+}
+
+func TestWriteVMOptions_RefusesDefaultGateway(t *testing.T) {
+	err := WriteVMOptions(t.TempDir(), subName, "i-web", []string{"i-web-1"}, Config{
+		InterfaceIP:    net.ParseIP("10.1.1.1").To4(),
+		DefaultGateway: net.ParseIP("10.1.1.254").To4(),
+	})
+	if err == nil {
+		t.Error("ces options servent à retirer la route par défaut : en porter une est une incohérence")
+	}
+}

internal/dispatcher/agent/vm_commands.go

@@ -19,10 +19,15 @@ type VMDisk struct {
 	Dev  string
 }
 
+type VMNIC struct {
+	Subnet  string
+	IP      string
+	Primary bool
+}
+
 type StartVMCommand struct {
 	Name      string
-	Subnet    string
-	IP        string
+	NICs      []VMNIC
 	Disks     []VMDisk
 	Memory    int
 	CPUs      int
@@ -38,20 +43,28 @@ func (c StartVMCommand) Prepare(db *badger.DB, _ *configuration.Config) error {
 	if _, err := kv.GetFromDB(db, "vm/"+c.Name+"/state"); err == nil {
 		return fmt.Errorf("vm %q already exists", c.Name)
 	}
-	subnetState, err := state.Get(db, "subnet/"+c.Subnet)
-	if err != nil {
-		return fmt.Errorf("subnet %q not found", c.Subnet)
-	}
-	if subnetState != state.Creating && subnetState != state.Running {
-		return fmt.Errorf("subnet %q is %s", c.Subnet, subnetState)
+	if err := c.validateNICs(db); err != nil {
+		return err
 	}
 	port, err := allocateMetadataPort(db)
 	if err != nil {
 		return fmt.Errorf("allocate metadata port: %w", err)
 	}
 	state.Set(db, c.Key(), state.Creating)
-	kv.AddInDB(db, "vm/"+c.Name+"/subnet", c.Subnet)
-	kv.AddInDB(db, "vm/"+c.Name+"/ip", c.IP)
+	for i, n := range c.NICs {
+		prefix := fmt.Sprintf("vm/%s/nic/%d/", c.Name, i)
+		if err := kv.AddInDB(db, prefix+"subnet", n.Subnet); err != nil {
+			return fmt.Errorf("store nic %d subnet: %w", i, err)
+		}
+		if err := kv.AddInDB(db, prefix+"ip", n.IP); err != nil {
+			return fmt.Errorf("store nic %d ip: %w", i, err)
+		}
+		if n.Primary {
+			if err := kv.AddInDB(db, prefix+"primary", "true"); err != nil {
+				return fmt.Errorf("store nic %d primary: %w", i, err)
+			}
+		}
+	}
 	kv.AddInDB(db, "vm/"+c.Name+"/metadata_port", strconv.Itoa(port))
 	for _, d := range c.Disks {
 		kv.AddInDB(db, "vm/"+c.Name+"/disk/"+d.Dev, d.Path)
@@ -75,6 +88,31 @@ func (c StartVMCommand) Prepare(db *badger.DB, _ *configuration.Config) error {
 	return nil
 }
 
+// validateNICs vérifie qu'il y a exactement une interface primaire et que
+// chaque subnet référencé est utilisable.
+func (c StartVMCommand) validateNICs(db *badger.DB) error {
+	if len(c.NICs) == 0 {
+		return fmt.Errorf("vm %q has no interface", c.Name)
+	}
+	primaries := 0
+	for _, n := range c.NICs {
+		if n.Primary {
+			primaries++
+		}
+		subnetState, err := state.Get(db, "subnet/"+n.Subnet)
+		if err != nil {
+			return fmt.Errorf("subnet %q not found", n.Subnet)
+		}
+		if subnetState != state.Creating && subnetState != state.Running {
+			return fmt.Errorf("subnet %q is %s", n.Subnet, subnetState)
+		}
+	}
+	if primaries != 1 {
+		return fmt.Errorf("vm %q has %d primary interfaces, expected exactly one", c.Name, primaries)
+	}
+	return nil
+}
+
 func allocateMetadataPort(db *badger.DB) (int, error) {
 	entries, err := kv.ListByPrefix(db, "vm/")
 	if err != nil {
@@ -99,21 +137,23 @@ func allocateMetadataPort(db *badger.DB) (int, error) {
 
 func (c StartVMCommand) Execute(db *badger.DB, cfg *configuration.Config) error {
 	timeout := time.After(time.Duration(cfg.Dispatcher.TimeoutSeconds) * time.Second)
-	for {
-		subnetState, err := state.Get(db, "subnet/"+c.Subnet)
-		if err != nil {
-			return fmt.Errorf("subnet %q not found while waiting", c.Subnet)
-		}
-		if subnetState == state.Running {
-			break
-		}
-		if subnetState != state.Creating {
-			return fmt.Errorf("subnet %q is %s, cannot start vm %q", c.Subnet, subnetState, c.Name)
-		}
-		select {
-		case <-timeout:
-			return fmt.Errorf("timed out waiting for subnet %q to be running", c.Subnet)
-		case <-time.After(time.Duration(cfg.Dispatcher.PollSeconds) * time.Second):
+	for _, n := range c.NICs {
+		for {
+			subnetState, err := state.Get(db, "subnet/"+n.Subnet)
+			if err != nil {
+				return fmt.Errorf("subnet %q not found while waiting", n.Subnet)
+			}
+			if subnetState == state.Running {
+				break
+			}
+			if subnetState != state.Creating {
+				return fmt.Errorf("subnet %q is %s, cannot start vm %q", n.Subnet, subnetState, c.Name)
+			}
+			select {
+			case <-timeout:
+				return fmt.Errorf("timed out waiting for subnet %q to be running", n.Subnet)
+			case <-time.After(time.Duration(cfg.Dispatcher.PollSeconds) * time.Second):
+			}
 		}
 	}
 	return vm.StartVM(db, c.Name, cfg)

internal/dispatcher/agent/vm_commands_test.go

@@ -15,10 +15,9 @@ func TestStartVMCommand_Prepare_SingleDisk(t *testing.T) {
 	kv.AddInDB(db, "subnet/sn-1/vpc", "vpc-1")
 
 	cmd := StartVMCommand{
-		Name:   "vm-1",
-		Subnet: "sn-1",
-		IP:     "10.0.0.5",
-		Disks:  []VMDisk{{Path: "/data/root.qcow2", Dev: "sda"}},
+		Name:  "vm-1",
+		NICs:  []VMNIC{{Subnet: "sn-1", IP: "10.0.0.5", Primary: true}},
+		Disks: []VMDisk{{Path: "/data/root.qcow2", Dev: "sda"}},
 	}
 	if err := cmd.Prepare(db, nil); err != nil {
 		t.Fatalf("Prepare a échoué : %v", err)
@@ -39,9 +38,8 @@ func TestStartVMCommand_Prepare_MultiDisk(t *testing.T) {
 	kv.AddInDB(db, "subnet/sn-1/vpc", "vpc-1")
 
 	cmd := StartVMCommand{
-		Name:   "vm-2",
-		Subnet: "sn-1",
-		IP:     "10.0.0.6",
+		Name: "vm-2",
+		NICs: []VMNIC{{Subnet: "sn-1", IP: "10.0.0.6", Primary: true}},
 		Disks: []VMDisk{
 			{Path: "/data/root.qcow2", Dev: "sda"},
 			{Path: "/data/data.qcow2", Dev: "sdb"},
@@ -72,9 +70,8 @@ func TestStartVMCommand_Prepare_SlotGap(t *testing.T) {
 
 	// sdb absent au boot — slot réservé pour hotplug
 	cmd := StartVMCommand{
-		Name:   "vm-3",
-		Subnet: "sn-1",
-		IP:     "10.0.0.7",
+		Name: "vm-3",
+		NICs: []VMNIC{{Subnet: "sn-1", IP: "10.0.0.7", Primary: true}},
 		Disks: []VMDisk{
 			{Path: "/data/root.qcow2", Dev: "sda"},
 			{Path: "/data/extra.qcow2", Dev: "sdc"},
@@ -101,10 +98,9 @@ func TestStartVMCommand_Prepare_NoVolumePath(t *testing.T) {
 	kv.AddInDB(db, "subnet/sn-1/vpc", "vpc-1")
 
 	cmd := StartVMCommand{
-		Name:   "vm-4",
-		Subnet: "sn-1",
-		IP:     "10.0.0.8",
-		Disks:  []VMDisk{{Path: "/data/root.qcow2", Dev: "sda"}},
+		Name:  "vm-4",
+		NICs:  []VMNIC{{Subnet: "sn-1", IP: "10.0.0.8", Primary: true}},
+		Disks: []VMDisk{{Path: "/data/root.qcow2", Dev: "sda"}},
 	}
 	if err := cmd.Prepare(db, nil); err != nil {
 		t.Fatalf("Prepare a échoué : %v", err)
@@ -165,10 +161,9 @@ func TestStartVMCommand_Prepare_Duplicate(t *testing.T) {
 	kv.AddInDB(db, "vm/vm-exist/state", "running")
 
 	cmd := StartVMCommand{
-		Name:   "vm-exist",
-		Subnet: "sn-1",
-		IP:     "10.0.0.9",
-		Disks:  []VMDisk{{Path: "/data/root.qcow2", Dev: "sda"}},
+		Name:  "vm-exist",
+		NICs:  []VMNIC{{Subnet: "sn-1", IP: "10.0.0.9", Primary: true}},
+		Disks: []VMDisk{{Path: "/data/root.qcow2", Dev: "sda"}},
 	}
 	if err := cmd.Prepare(db, nil); err == nil {
 		t.Error("Prepare devrait échouer si la VM existe déjà")
@@ -185,8 +180,7 @@ func prepareWithDocuments(t *testing.T, docs map[string]string) *badger.DB {
 
 	cmd := StartVMCommand{
 		Name:      "vm-doc",
-		Subnet:    "sn-1",
-		IP:        "10.0.0.5",
+		NICs:      []VMNIC{{Subnet: "sn-1", IP: "10.0.0.5", Primary: true}},
 		Disks:     []VMDisk{{Path: "/data/root.qcow2", Dev: "vda"}},
 		Documents: docs,
 	}

internal/migration/nic.go

@@ -0,0 +1,76 @@
+package migration
+
+import (
+	"fmt"
+	"log/slog"
+	"strings"
+
+	"git.g3e.fr/syonad/two/pkg/db/kv"
+
+	"github.com/dgraph-io/badger/v4"
+)
+
+// legacyNICKeys sont les clés d'interface d'avant le multi-subnet, portées
+// directement par la VM.
+var legacyNICKeys = []string{"subnet", "ip", "tap_id"}
+
+// MigrateVMNICs déplace les clés d'interface de vm/<name>/<clé> vers
+// vm/<name>/nic/0/<clé> et marque cette interface comme primaire.
+//
+// Idempotente : une VM possédant déjà des clés nic/ est laissée telle quelle.
+// Sans cette migration, toute VM créée avant le passage au multi-subnet
+// deviendrait illisible par loadVM.
+func MigrateVMNICs(db *badger.DB, log *slog.Logger) error {
+	entries, err := kv.ListByPrefix(db, "vm/")
+	if err != nil {
+		return fmt.Errorf("list vm/: %w", err)
+	}
+
+	for _, name := range vmsToMigrate(entries) {
+		for _, key := range legacyNICKeys {
+			value, ok := entries["vm/"+name+"/"+key]
+			if !ok {
+				continue
+			}
+			if err := kv.AddInDB(db, "vm/"+name+"/nic/0/"+key, value); err != nil {
+				return fmt.Errorf("migrate %s of vm %s: %w", key, name, err)
+			}
+			if err := kv.DeleteInDB(db, "vm/"+name+"/"+key); err != nil {
+				return fmt.Errorf("delete legacy %s of vm %s: %w", key, name, err)
+			}
+		}
+		if err := kv.AddInDB(db, "vm/"+name+"/nic/0/primary", "true"); err != nil {
+			return fmt.Errorf("mark nic 0 primary for vm %s: %w", name, err)
+		}
+		log.Info("vm nics migrated", "resource", "vm/"+name, "reason", "legacy single interface")
+	}
+	return nil
+}
+
+// vmsToMigrate retourne les VM portant l'ancien schéma et aucune clé nic/.
+func vmsToMigrate(entries map[string]string) []string {
+	legacy := make(map[string]bool)
+	migrated := make(map[string]bool)
+
+	for key := range entries {
+		parts := strings.Split(key, "/")
+		if len(parts) < 3 || parts[0] != "vm" {
+			continue
+		}
+		name := parts[1]
+		switch {
+		case len(parts) == 3 && (parts[2] == "subnet" || parts[2] == "ip" || parts[2] == "tap_id"):
+			legacy[name] = true
+		case parts[2] == "nic":
+			migrated[name] = true
+		}
+	}
+
+	var names []string
+	for name := range legacy {
+		if !migrated[name] {
+			names = append(names, name)
+		}
+	}
+	return names
+}

internal/migration/nic_test.go

@@ -0,0 +1,136 @@
+package migration
+
+import (
+	"io"
+	"log/slog"
+	"testing"
+
+	"git.g3e.fr/syonad/two/pkg/db/kv"
+	"github.com/dgraph-io/badger/v4"
+)
+
+func newNICDB(t *testing.T) *badger.DB {
+	t.Helper()
+	db := kv.InitDB(kv.Config{Path: t.TempDir()}, false)
+	t.Cleanup(func() { db.Close() })
+	return db
+}
+
+func quietLog() *slog.Logger {
+	return slog.New(slog.NewTextHandler(io.Discard, nil))
+}
+
+func seedLegacyVM(t *testing.T, db *badger.DB, name string) {
+	t.Helper()
+	kv.AddInDB(db, "vm/"+name+"/state", "running")
+	kv.AddInDB(db, "vm/"+name+"/subnet", "sn-000001")
+	kv.AddInDB(db, "vm/"+name+"/ip", "10.1.1.2")
+	kv.AddInDB(db, "vm/"+name+"/tap_id", "12345678")
+}
+
+func TestMigrateVMNICs_MovesLegacyKeys(t *testing.T) {
+	db := newNICDB(t)
+	seedLegacyVM(t, db, "i-test1")
+
+	if err := MigrateVMNICs(db, quietLog()); err != nil {
+		t.Fatalf("MigrateVMNICs : %v", err)
+	}
+
+	want := map[string]string{
+		"vm/i-test1/nic/0/subnet":  "sn-000001",
+		"vm/i-test1/nic/0/ip":      "10.1.1.2",
+		"vm/i-test1/nic/0/tap_id":  "12345678",
+		"vm/i-test1/nic/0/primary": "true",
+	}
+	for key, expected := range want {
+		got, err := kv.GetFromDB(db, key)
+		if err != nil {
+			t.Errorf("clé %s absente : %v", key, err)
+			continue
+		}
+		if got != expected {
+			t.Errorf("%s = %q, attendu %q", key, got, expected)
+		}
+	}
+}
+
+func TestMigrateVMNICs_RemovesLegacyKeys(t *testing.T) {
+	db := newNICDB(t)
+	seedLegacyVM(t, db, "i-test1")
+
+	if err := MigrateVMNICs(db, quietLog()); err != nil {
+		t.Fatalf("MigrateVMNICs : %v", err)
+	}
+
+	for _, key := range []string{"vm/i-test1/subnet", "vm/i-test1/ip", "vm/i-test1/tap_id"} {
+		if _, err := kv.GetFromDB(db, key); err == nil {
+			t.Errorf("clé héritée %s toujours présente", key)
+		}
+	}
+}
+
+func TestMigrateVMNICs_PreservesOtherKeys(t *testing.T) {
+	db := newNICDB(t)
+	seedLegacyVM(t, db, "i-test1")
+	kv.AddInDB(db, "vm/i-test1/memory", "2048")
+	kv.AddInDB(db, "vm/i-test1/disk/vda", "/data/root.qcow2")
+
+	if err := MigrateVMNICs(db, quietLog()); err != nil {
+		t.Fatalf("MigrateVMNICs : %v", err)
+	}
+
+	if got, _ := kv.GetFromDB(db, "vm/i-test1/memory"); got != "2048" {
+		t.Errorf("memory altérée : %q", got)
+	}
+	if got, _ := kv.GetFromDB(db, "vm/i-test1/disk/vda"); got != "/data/root.qcow2" {
+		t.Errorf("disque altéré : %q", got)
+	}
+}
+
+func TestMigrateVMNICs_Idempotent(t *testing.T) {
+	db := newNICDB(t)
+	seedLegacyVM(t, db, "i-test1")
+
+	if err := MigrateVMNICs(db, quietLog()); err != nil {
+		t.Fatalf("premier passage : %v", err)
+	}
+	before, _ := kv.ListByPrefix(db, "vm/i-test1/")
+	if err := MigrateVMNICs(db, quietLog()); err != nil {
+		t.Fatalf("second passage : %v", err)
+	}
+	after, _ := kv.ListByPrefix(db, "vm/i-test1/")
+
+	if len(before) != len(after) {
+		t.Errorf("le second passage a modifié la base : %d clés puis %d", len(before), len(after))
+	}
+	for key, value := range before {
+		if after[key] != value {
+			t.Errorf("%s : %q devenu %q", key, value, after[key])
+		}
+	}
+}
+
+func TestMigrateVMNICs_LeavesMigratedVMsAlone(t *testing.T) {
+	db := newNICDB(t)
+	kv.AddInDB(db, "vm/i-multi/state", "running")
+	kv.AddInDB(db, "vm/i-multi/nic/0/subnet", "sn-000001")
+	kv.AddInDB(db, "vm/i-multi/nic/0/primary", "true")
+	kv.AddInDB(db, "vm/i-multi/nic/1/subnet", "sn-000002")
+
+	if err := MigrateVMNICs(db, quietLog()); err != nil {
+		t.Fatalf("MigrateVMNICs : %v", err)
+	}
+
+	if got, _ := kv.GetFromDB(db, "vm/i-multi/nic/1/subnet"); got != "sn-000002" {
+		t.Errorf("la seconde interface a été perdue : %q", got)
+	}
+	if _, err := kv.GetFromDB(db, "vm/i-multi/nic/0/primary"); err != nil {
+		t.Error("la primaire existante a été perdue")
+	}
+}
+
+func TestMigrateVMNICs_EmptyDB(t *testing.T) {
+	if err := MigrateVMNICs(newNICDB(t), quietLog()); err != nil {
+		t.Errorf("une base vide ne doit pas échouer : %v", err)
+	}
+}

internal/qemu/config.go

@@ -9,10 +9,16 @@ type DiskConfig struct {
 	Dev  string
 }
 
+// NICConfig décrit une interface réseau. Sa position dans Config.NICs
+// détermine le slot PCI, donc le nom de l'interface dans le guest.
+type NICConfig struct {
+	TapID int
+	Mac   string
+}
+
 type Config struct {
 	Name         string
-	TapID        int
-	Mac          string
+	NICs         []NICConfig
 	Disks        []DiskConfig
 	Memory       int
 	CPUs         int

internal/qemu/start_linux.go

@@ -11,6 +11,12 @@ import (
 	"strings"
 )
 
+const (
+	firstNICSlot = 0x03
+	lastNICSlot  = 0x1d
+	maxNICs      = lastNICSlot - firstNICSlot + 1
+)
+
 func Start(cfg Config) error {
 	memory := cfg.Memory
 	if memory == 0 {
@@ -97,11 +103,24 @@ func Start(cfg Config) error {
 		}
 	}
 
-	args = append(args,
-		"-netdev", fmt.Sprintf("tap,id=net0,ifname=tap%d,script=no,downscript=no", cfg.TapID),
-		"-device", fmt.Sprintf("virtio-net-pci,netdev=net0,mac=%s,bus=pci.0,addr=0x03", cfg.Mac),
-		"-daemonize",
-	)
+	// Slots 0x03 à 0x1d réservés au réseau par la carte PCI (#36). Le slot est
+	// dérivé de l'index et non laissé à QEMU : c'est lui qui fixe le nom de
+	// l'interface dans le guest, et un slot flottant la renomme d'un démarrage
+	// à l'autre.
+	if len(cfg.NICs) == 0 {
+		return fmt.Errorf("vm %s has no network interface", cfg.Name)
+	}
+	if len(cfg.NICs) > maxNICs {
+		return fmt.Errorf("vm %s has %d interfaces, the pci map holds %d", cfg.Name, len(cfg.NICs), maxNICs)
+	}
+	for i, n := range cfg.NICs {
+		args = append(args,
+			"-netdev", fmt.Sprintf("tap,id=net%d,ifname=tap%d,script=no,downscript=no", i, n.TapID),
+			"-device", fmt.Sprintf("virtio-net-pci,netdev=net%d,mac=%s,bus=pci.0,addr=0x%02x", i, n.Mac, firstNICSlot+i),
+		)
+	}
+
+	args = append(args, "-daemonize")
 
 	scopeArgs := append([]string{
 		"--scope",

internal/vm/create.go

@@ -3,6 +3,7 @@ package vm
 import (
 	"fmt"
 	"io"
+	"net"
 	"os"
 	"path/filepath"
 
@@ -31,26 +32,36 @@ func StartVM(db *badger.DB, name string, cfg *configuration.Config) error {
 	if err != nil {
 		return err
 	}
+	nic := d.primary()
 
-	if err := netif.CreateTap(d.tapID, d.bridge, d.vpcName); err != nil {
-		return fmt.Errorf("create tap: %w", err)
+	for _, n := range d.nics {
+		if err := netif.CreateTap(n.tapID, n.bridge, n.vpcName); err != nil {
+			return fmt.Errorf("create tap of interface %d: %w", n.index, err)
+		}
 	}
 
-	if err := netns.Call(d.vpcName, func() error {
-		return iptables.AddMetadataRedirect(d.ip, d.interfaceIP, d.metadataPort)
+	// La redirection est posée pour chaque IP de la VM vers le serveur de
+	// métadonnées de l'interface primaire. Toutes les interfaces étant dans le
+	// même VPC, donc le même netns, il est joignable depuis n'importe laquelle.
+	if err := netns.Call(nic.vpcName, func() error {
+		for _, n := range d.nics {
+			if err := iptables.AddMetadataRedirect(n.ip, nic.interfaceIP, d.metadataPort); err != nil {
+				return fmt.Errorf("interface %d: %w", n.index, err)
+			}
+		}
+		return nil
 	}); err != nil {
 		return fmt.Errorf("add metadata redirect: %w", err)
 	}
 
-	if err := dhcp.WriteReservations(dhcp.DefaultConfDir, d.vpcName+"_"+d.bridge, name,
-		[]dhcp.Reservation{{MAC: d.mac, IP: d.ip}}); err != nil {
-		return fmt.Errorf("write dhcp reservation: %w", err)
+	if err := writeDHCPFiles(d, name); err != nil {
+		return err
 	}
 
 	if err := metadata.StartMetadata(metadata.NoCloudConfig{
 		Name:      name,
-		VpcName:   d.vpcName,
-		BindIP:    d.interfaceIP,
+		VpcName:   nic.vpcName,
+		BindIP:    nic.interfaceIP,
 		BindPort:  d.metadataPort,
 		Password:  d.password,
 		SSHKEY:    d.sshkey,
@@ -64,10 +75,14 @@ func StartVM(db *badger.DB, name string, cfg *configuration.Config) error {
 		qDisks[i] = qemu.DiskConfig{Path: disk.path, Dev: disk.dev}
 	}
 
+	qNICs := make([]qemu.NICConfig, len(d.nics))
+	for i, n := range d.nics {
+		qNICs[i] = qemu.NICConfig{TapID: n.tapID, Mac: n.mac}
+	}
+
 	qcfg := qemu.Config{
 		Name:       name,
-		TapID:      d.tapID,
-		Mac:        d.mac,
+		NICs:       qNICs,
 		Disks:      qDisks,
 		Memory:     d.memory,
 		CPUs:       d.cpus,
@@ -85,7 +100,7 @@ func StartVM(db *badger.DB, name string, cfg *configuration.Config) error {
 		qcfg.UEFIVarsPath = varsPath
 	}
 
-	if err := netns.Call(d.vpcName, func() error {
+	if err := netns.Call(nic.vpcName, func() error {
 		return qemu.Start(qcfg)
 	}); err != nil {
 		return fmt.Errorf("start qemu: %w", err)
@@ -94,6 +109,53 @@ func StartVM(db *badger.DB, name string, cfg *configuration.Config) error {
 	return state.Set(db, "vm/"+name, state.Running)
 }
 
+// writeDHCPFiles écrit, pour chaque subnet touché par la VM, les réservations
+// de ses interfaces et les options qui suppriment la route par défaut sur les
+// interfaces non primaires. Le subnet de l'interface primaire ne reçoit aucune
+// option : les options non taggées du subnet portent déjà la route par défaut.
+func writeDHCPFiles(d vmData, name string) error {
+	type subnetFiles struct {
+		nic          nicData
+		reservations []dhcp.Reservation
+		tags         []string
+	}
+	bySubnet := make(map[string]*subnetFiles)
+
+	for _, n := range d.nics {
+		confName := n.vpcName + "_" + n.bridge
+		if bySubnet[confName] == nil {
+			bySubnet[confName] = &subnetFiles{nic: n}
+		}
+		f := bySubnet[confName]
+		f.reservations = append(f.reservations, dhcp.Reservation{
+			MAC: n.mac, IP: n.ip, Tag: nicTag(name, n.index),
+		})
+		if !n.primary {
+			f.tags = append(f.tags, nicTag(name, n.index))
+		}
+	}
+
+	for confName, f := range bySubnet {
+		if err := dhcp.WriteReservations(dhcp.DefaultConfDir, confName, name, f.reservations); err != nil {
+			return fmt.Errorf("write dhcp reservations on %s: %w", confName, err)
+		}
+		if err := dhcp.WriteVMOptions(dhcp.DefaultConfDir, confName, name, f.tags, dhcp.Config{
+			InterfaceIP: net.ParseIP(f.nic.interfaceIP),
+			VPCRoute:    f.nic.vpcCIDR,
+		}); err != nil {
+			return fmt.Errorf("write dhcp options on %s: %w", confName, err)
+		}
+	}
+	return nil
+}
+
+// nicTag identifie une interface auprès de dnsmasq. Il est par interface et non
+// par VM : deux interfaces d'une même VM peuvent partager un subnet, et n'y
+// avoir pas le même rôle.
+func nicTag(vmName string, index int) string {
+	return fmt.Sprintf("%s-%d", vmName, index)
+}
+
 func copyFile(src, dst string) error {
 	if err := os.MkdirAll(filepath.Dir(dst), 0755); err != nil {
 		return err

internal/vm/data.go

@@ -3,6 +3,8 @@ package vm
 import (
 	"fmt"
 	"math/rand"
+	"net"
+	"sort"
 	"strconv"
 	"strings"
 
@@ -16,15 +18,23 @@ type diskEntry struct {
 	dev  string
 }
 
+type nicData struct {
+	index       int
+	subnetName  string
+	vpcName     string
+	bridge      string
+	interfaceIP string
+	ip          string
+	mac         string
+	tapID       int
+	primary     bool
+	mode        string
+	vpcCIDR     *net.IPNet
+}
+
 type vmData struct {
-	subnetName   string
-	vpcName      string
-	interfaceIP  string
-	bridge       string
-	tapID        int
-	ip           string
+	nics         []nicData
 	metadataPort string
-	mac          string
 	disks        []diskEntry
 	memory       int
 	cpus         int
@@ -34,47 +44,25 @@ type vmData struct {
 	documents    map[string]string
 }
 
+// primary retourne l'interface portant la route par défaut et le serveur de
+// métadonnées. loadVM garantit qu'il y en a exactement une.
+func (d vmData) primary() nicData {
+	for _, n := range d.nics {
+		if n.primary {
+			return n
+		}
+	}
+	return nicData{}
+}
+
 func loadVM(db *badger.DB, name string) (vmData, error) {
 	var d vmData
 
-	subnetName, err := kv.GetFromDB(db, "vm/"+name+"/subnet")
+	nics, err := loadNICs(db, name)
 	if err != nil {
-		return d, fmt.Errorf("get subnet: %w", err)
+		return d, err
 	}
-	d.subnetName = subnetName
-	d.bridge = "br-" + strings.SplitN(subnetName, "-", 2)[1]
-
-	vpcName, err := kv.GetFromDB(db, "subnet/"+subnetName+"/vpc")
-	if err != nil {
-		return d, fmt.Errorf("get vpc: %w", err)
-	}
-	d.vpcName = vpcName
-
-	interfaceIP, err := kv.GetFromDB(db, "subnet/"+subnetName+"/interface_ip")
-	if err != nil {
-		return d, fmt.Errorf("get interface_ip: %w", err)
-	}
-	d.interfaceIP = interfaceIP
-
-	tapIDStr, err := kv.GetFromDB(db, "vm/"+name+"/tap_id")
-	if err != nil {
-		d.tapID = rand.Intn(90000000) + 10000000
-		if err := kv.AddInDB(db, "vm/"+name+"/tap_id", strconv.Itoa(d.tapID)); err != nil {
-			return d, fmt.Errorf("store tap_id: %w", err)
-		}
-	} else {
-		tapID, err := strconv.Atoi(tapIDStr)
-		if err != nil {
-			return d, fmt.Errorf("parse tap_id: %w", err)
-		}
-		d.tapID = tapID
-	}
-
-	ip, err := kv.GetFromDB(db, "vm/"+name+"/ip")
-	if err != nil {
-		return d, fmt.Errorf("get ip: %w", err)
-	}
-	d.ip = ip
+	d.nics = nics
 
 	metadataPort, err := kv.GetFromDB(db, "vm/"+name+"/metadata_port")
 	if err != nil {
@@ -82,12 +70,6 @@ func loadVM(db *badger.DB, name string) (vmData, error) {
 	}
 	d.metadataPort = metadataPort
 
-	mac, err := dhcp.GetMACForIP(db, d.subnetName, d.ip)
-	if err != nil {
-		return d, fmt.Errorf("get mac for ip %s: %w", d.ip, err)
-	}
-	d.mac = mac
-
 	diskEntries, err := kv.ListByPrefix(db, "vm/"+name+"/disk/")
 	if err != nil {
 		return d, fmt.Errorf("list disks: %w", err)
@@ -139,3 +121,118 @@ func loadVM(db *badger.DB, name string) (vmData, error) {
 
 	return d, nil
 }
+
+// loadNICs lit les interfaces d'une VM sous vm/<name>/nic/<index>/.
+// Le tap est alloué à la première lecture et persisté, comme avant le passage
+// au multi-interfaces — mais désormais par interface.
+func loadNICs(db *badger.DB, name string) ([]nicData, error) {
+	prefix := "vm/" + name + "/nic/"
+	entries, err := kv.ListByPrefix(db, prefix)
+	if err != nil {
+		return nil, fmt.Errorf("list nics: %w", err)
+	}
+
+	indexes := make(map[int]bool)
+	for key := range entries {
+		parts := strings.Split(strings.TrimPrefix(key, prefix), "/")
+		if len(parts) != 2 {
+			continue
+		}
+		idx, err := strconv.Atoi(parts[0])
+		if err != nil {
+			return nil, fmt.Errorf("invalid nic index %q for vm %s", parts[0], name)
+		}
+		indexes[idx] = true
+	}
+	if len(indexes) == 0 {
+		return nil, fmt.Errorf("no interface found for vm %q", name)
+	}
+
+	nics := make([]nicData, 0, len(indexes))
+	for idx := range indexes {
+		n, err := loadNIC(db, name, idx, entries)
+		if err != nil {
+			return nil, err
+		}
+		nics = append(nics, n)
+	}
+	sort.Slice(nics, func(i, j int) bool { return nics[i].index < nics[j].index })
+
+	primaries := 0
+	for _, n := range nics {
+		if n.primary {
+			primaries++
+		}
+	}
+	if primaries != 1 {
+		return nil, fmt.Errorf("vm %q has %d primary interfaces, expected exactly one", name, primaries)
+	}
+	return nics, nil
+}
+
+func loadNIC(db *badger.DB, name string, idx int, entries map[string]string) (nicData, error) {
+	n := nicData{index: idx}
+	prefix := fmt.Sprintf("vm/%s/nic/%d/", name, idx)
+
+	n.subnetName = entries[prefix+"subnet"]
+	if n.subnetName == "" {
+		return n, fmt.Errorf("nic %d of vm %s has no subnet", idx, name)
+	}
+	n.bridge = "br-" + strings.SplitN(n.subnetName, "-", 2)[1]
+	n.primary = entries[prefix+"primary"] == "true"
+
+	vpcName, err := kv.GetFromDB(db, "subnet/"+n.subnetName+"/vpc")
+	if err != nil {
+		return n, fmt.Errorf("get vpc of subnet %s: %w", n.subnetName, err)
+	}
+	n.vpcName = vpcName
+
+	interfaceIP, err := kv.GetFromDB(db, "subnet/"+n.subnetName+"/interface_ip")
+	if err != nil {
+		return n, fmt.Errorf("get interface_ip of subnet %s: %w", n.subnetName, err)
+	}
+	n.interfaceIP = interfaceIP
+
+	n.mode, err = kv.GetFromDB(db, "subnet/"+n.subnetName+"/mode")
+	if err != nil {
+		return n, fmt.Errorf("get mode of subnet %s: %w", n.subnetName, err)
+	}
+
+	if n.mode != "bridge" {
+		cidrStr, err := kv.GetFromDB(db, "vpc/"+n.vpcName+"/cidr")
+		if err != nil {
+			return n, fmt.Errorf("get cidr of vpc %s: %w", n.vpcName, err)
+		}
+		_, vpcCIDR, err := net.ParseCIDR(cidrStr)
+		if err != nil {
+			return n, fmt.Errorf("parse cidr of vpc %s: %w", n.vpcName, err)
+		}
+		n.vpcCIDR = vpcCIDR
+	}
+
+	n.ip = entries[prefix+"ip"]
+	if n.ip == "" {
+		return n, fmt.Errorf("nic %d of vm %s has no ip", idx, name)
+	}
+
+	mac, err := dhcp.GetMACForIP(db, n.subnetName, n.ip)
+	if err != nil {
+		return n, fmt.Errorf("get mac for ip %s: %w", n.ip, err)
+	}
+	n.mac = mac
+
+	if tapIDStr, ok := entries[prefix+"tap_id"]; ok {
+		tapID, err := strconv.Atoi(tapIDStr)
+		if err != nil {
+			return n, fmt.Errorf("parse tap_id of nic %d: %w", idx, err)
+		}
+		n.tapID = tapID
+		return n, nil
+	}
+
+	n.tapID = rand.Intn(90000000) + 10000000
+	if err := kv.AddInDB(db, prefix+"tap_id", strconv.Itoa(n.tapID)); err != nil {
+		return n, fmt.Errorf("store tap_id of nic %d: %w", idx, err)
+	}
+	return n, nil
+}

internal/vm/data_test.go

@@ -1,6 +1,8 @@
 package vm
 
 import (
+	"fmt"
+	"strconv"
 	"testing"
 
 	"git.g3e.fr/syonad/two/pkg/db/kv"
@@ -12,11 +14,14 @@ func newVMInDB(t *testing.T) *badger.DB {
 	db := kv.InitDB(kv.Config{Path: t.TempDir()}, false)
 	t.Cleanup(func() { db.Close() })
 
-	kv.AddInDB(db, "vm/vm-1/subnet", "sn-000001")
+	kv.AddInDB(db, "vm/vm-1/nic/0/subnet", "sn-000001")
+	kv.AddInDB(db, "vm/vm-1/nic/0/primary", "true")
 	kv.AddInDB(db, "subnet/sn-000001/vpc", "vp-admin")
 	kv.AddInDB(db, "subnet/sn-000001/interface_ip", "10.1.1.1")
+	kv.AddInDB(db, "subnet/sn-000001/mode", "vxlan")
+	kv.AddInDB(db, "vpc/vp-admin/cidr", "192.168.0.0/16")
 	kv.AddInDB(db, "subnet/sn-000001/dhcp/10.1.1.2", "00:22:33:00:01:02")
-	kv.AddInDB(db, "vm/vm-1/ip", "10.1.1.2")
+	kv.AddInDB(db, "vm/vm-1/nic/0/ip", "10.1.1.2")
 	kv.AddInDB(db, "vm/vm-1/metadata_port", "8081")
 	kv.AddInDB(db, "vm/vm-1/disk/vda", "/data/root.qcow2")
 	kv.AddInDB(db, "vm/vm-1/memory", "2048")
@@ -88,3 +93,109 @@ func TestLoadVM_EmptyDocumentIsPreserved(t *testing.T) {
 		t.Errorf("contenu attendu vide, obtenu %q", content)
 	}
 }
+
+// --- multi-interfaces ---
+
+func addNIC(t *testing.T, db *badger.DB, idx int, subnet, ip, mac string, primary bool) {
+	t.Helper()
+	prefix := fmt.Sprintf("vm/vm-1/nic/%d/", idx)
+	kv.AddInDB(db, prefix+"subnet", subnet)
+	kv.AddInDB(db, prefix+"ip", ip)
+	if primary {
+		kv.AddInDB(db, prefix+"primary", "true")
+	}
+	kv.AddInDB(db, "subnet/"+subnet+"/vpc", "vp-admin")
+	kv.AddInDB(db, "subnet/"+subnet+"/interface_ip", "10.1.1.1")
+	kv.AddInDB(db, "subnet/"+subnet+"/mode", "vxlan")
+	kv.AddInDB(db, "vpc/vp-admin/cidr", "192.168.0.0/16")
+	kv.AddInDB(db, "subnet/"+subnet+"/dhcp/"+ip, mac)
+}
+
+func TestLoadVM_SingleNIC(t *testing.T) {
+	d, err := loadVM(newVMInDB(t), "vm-1")
+	if err != nil {
+		t.Fatalf("loadVM : %v", err)
+	}
+	if len(d.nics) != 1 {
+		t.Fatalf("1 interface attendue, obtenu %d", len(d.nics))
+	}
+	if !d.primary().primary || d.primary().ip != "10.1.1.2" {
+		t.Errorf("primaire inattendue : %+v", d.primary())
+	}
+}
+
+func TestLoadVM_MultipleNICsSortedByIndex(t *testing.T) {
+	db := newVMInDB(t)
+	addNIC(t, db, 2, "sn-000003", "10.3.0.9", "00:22:33:00:03:09", false)
+	addNIC(t, db, 1, "sn-000002", "10.2.0.5", "00:22:33:00:02:05", false)
+
+	d, err := loadVM(db, "vm-1")
+	if err != nil {
+		t.Fatalf("loadVM : %v", err)
+	}
+	if len(d.nics) != 3 {
+		t.Fatalf("3 interfaces attendues, obtenu %d", len(d.nics))
+	}
+	for i, n := range d.nics {
+		if n.index != i {
+			t.Errorf("interface en position %d porte l'index %d — l'ordre détermine le slot PCI", i, n.index)
+		}
+	}
+}
+
+func TestLoadVM_TapAllocatedPerNIC(t *testing.T) {
+	db := newVMInDB(t)
+	addNIC(t, db, 1, "sn-000002", "10.2.0.5", "00:22:33:00:02:05", false)
+
+	d, err := loadVM(db, "vm-1")
+	if err != nil {
+		t.Fatalf("loadVM : %v", err)
+	}
+	if d.nics[0].tapID == d.nics[1].tapID {
+		t.Errorf("deux interfaces partagent le tap %d", d.nics[0].tapID)
+	}
+	for _, n := range d.nics {
+		stored, err := kv.GetFromDB(db, fmt.Sprintf("vm/vm-1/nic/%d/tap_id", n.index))
+		if err != nil {
+			t.Errorf("tap_id de l'interface %d non persisté : %v", n.index, err)
+			continue
+		}
+		if stored != strconv.Itoa(n.tapID) {
+			t.Errorf("tap_id de l'interface %d : %q en base, %d en mémoire", n.index, stored, n.tapID)
+		}
+	}
+}
+
+func TestLoadVM_NoPrimaryIsAnError(t *testing.T) {
+	db := kv.InitDB(kv.Config{Path: t.TempDir()}, false)
+	t.Cleanup(func() { db.Close() })
+	kv.AddInDB(db, "vm/vm-1/metadata_port", "8081")
+	kv.AddInDB(db, "vm/vm-1/disk/vda", "/data/root.qcow2")
+	kv.AddInDB(db, "vm/vm-1/memory", "2048")
+	kv.AddInDB(db, "vm/vm-1/cpus", "2")
+	addNIC(t, db, 0, "sn-000001", "10.1.1.2", "00:22:33:00:01:02", false)
+	kv.AddInDB(db, "subnet/sn-000001/mode", "vxlan")
+
+	if _, err := loadVM(db, "vm-1"); err == nil {
+		t.Error("aucune interface primaire : loadVM doit échouer plutôt que de laisser StartVM choisir au hasard")
+	}
+}
+
+func TestLoadVM_TwoPrimariesIsAnError(t *testing.T) {
+	db := newVMInDB(t)
+	addNIC(t, db, 1, "sn-000002", "10.2.0.5", "00:22:33:00:02:05", true)
+
+	if _, err := loadVM(db, "vm-1"); err == nil {
+		t.Error("deux interfaces primaires doivent être refusées")
+	}
+}
+
+func TestLoadVM_NoNICIsAnError(t *testing.T) {
+	db := kv.InitDB(kv.Config{Path: t.TempDir()}, false)
+	t.Cleanup(func() { db.Close() })
+	kv.AddInDB(db, "vm/vm-1/memory", "2048")
+
+	if _, err := loadVM(db, "vm-1"); err == nil {
+		t.Error("une VM sans interface doit être refusée")
+	}
+}

internal/vm/delete.go

@@ -32,6 +32,7 @@ func StopVM(db *badger.DB, name string, cfg *configuration.Config) error {
 	if err != nil {
 		return err
 	}
+	nic := d.primary()
 
 	socketPath := filepath.Join(cfg.QEMU.QMPDir, name+".sock")
 
@@ -47,8 +48,13 @@ func StopVM(db *badger.DB, name string, cfg *configuration.Config) error {
 	}
 	// socket absent ou QEMU déjà arrêté : cleanup direct
 
-	if err := netns.Call(d.vpcName, func() error {
-		return iptables.DeleteMetadataRedirect(d.ip, d.interfaceIP, d.metadataPort)
+	if err := netns.Call(nic.vpcName, func() error {
+		for _, n := range d.nics {
+			if err := iptables.DeleteMetadataRedirect(n.ip, nic.interfaceIP, d.metadataPort); err != nil {
+				return fmt.Errorf("interface %d: %w", n.index, err)
+			}
+		}
+		return nil
 	}); err != nil {
 		return fmt.Errorf("delete metadata redirect: %w", err)
 	}
@@ -57,11 +63,13 @@ func StopVM(db *badger.DB, name string, cfg *configuration.Config) error {
 		return fmt.Errorf("stop metadata: %w", err)
 	}
 
-	if err := netif.DeleteTap(d.tapID, d.vpcName); err != nil {
-		return fmt.Errorf("delete tap: %w", err)
+	for _, n := range d.nics {
+		if err := netif.DeleteTap(n.tapID, n.vpcName); err != nil {
+			return fmt.Errorf("delete tap of interface %d: %w", n.index, err)
+		}
 	}
 
-	if err := removeDHCPReservation(d, name); err != nil {
+	if err := removeDHCPFiles(d, name); err != nil {
 		return err
 	}
 
@@ -73,12 +81,26 @@ func StopVM(db *badger.DB, name string, cfg *configuration.Config) error {
 	return state.Set(db, "vm/"+name, state.Deleted)
 }
 
-// removeDHCPReservation retire le fichier de réservation puis redémarre dnsmasq :
-// un fichier ajouté dans un dhcp-hostsdir est relu à chaud, un fichier retiré ne
-// l'est pas (vérifié sur dnsmasq 2.90).
-func removeDHCPReservation(d vmData, name string) error {
-	confName := d.vpcName + "_" + d.bridge
+// removeDHCPFiles retire les fichiers de la VM dans chaque subnet qu'elle
+// touche, puis redémarre les dnsmasq concernés : un fichier ajouté dans un
+// dhcp-hostsdir est relu à chaud, un fichier retiré ne l'est pas (vérifié sur
+// dnsmasq 2.90).
+func removeDHCPFiles(d vmData, name string) error {
+	seen := make(map[string]bool)
+	for _, n := range d.nics {
+		confName := n.vpcName + "_" + n.bridge
+		if seen[confName] {
+			continue
+		}
+		seen[confName] = true
+		if err := removeDHCPReservation(confName, name); err != nil {
+			return err
+		}
+	}
+	return nil
+}
 
+func removeDHCPReservation(confName, name string) error {
 	if err := dhcp.RemoveReservations(dhcp.DefaultConfDir, confName, name); err != nil {
 		return err
 	}

internal/watchdog/check_vm.go

@@ -4,7 +4,9 @@ import (
 	"errors"
 	"fmt"
 	"path/filepath"
+	"sort"
 	"strconv"
+	"strings"
 
 	configuration "git.g3e.fr/syonad/two/internal/config/agent"
 	"git.g3e.fr/syonad/two/internal/netns"
@@ -46,33 +48,65 @@ func CheckVMs(db *badger.DB, cfg *configuration.Config, u unitChecker, n notify.
 }
 
 func checkVM(db *badger.DB, cfg *configuration.Config, name string, u unitChecker, n notify.Notifier) {
-	subnetName, err := kv.GetFromDB(db, prefixVM+name+"/subnet")
+	entries, err := kv.ListByPrefix(db, prefixVM+name+"/nic/")
 	if err != nil {
-		n.Notify(kindVM, name, fmt.Sprintf("subnet unreadable in database: %v", err))
+		n.Notify(kindVM, name, fmt.Sprintf("interfaces unreadable in database: %v", err))
+		return
+	}
+	indexes := nicIndexes(entries, prefixVM+name+"/nic/")
+	if len(indexes) == 0 {
+		n.Notify(kindVM, name, "no interface in database")
 		return
 	}
 
-	vpc, err := kv.GetFromDB(db, prefixSubnet+subnetName+"/vpc")
-	if err != nil {
-		n.Notify(kindVM, name, fmt.Sprintf("vpc of subnet %s unreadable in database: %v", subnetName, err))
-		return
+	for _, idx := range indexes {
+		prefix := fmt.Sprintf("%s%s/nic/%d/", prefixVM, name, idx)
+		subnetName := entries[prefix+"subnet"]
+		if subnetName == "" {
+			n.Notify(kindVM, name, fmt.Sprintf("interface %d has no subnet in database", idx))
+			continue
+		}
+		vpc, err := kv.GetFromDB(db, prefixSubnet+subnetName+"/vpc")
+		if err != nil {
+			n.Notify(kindVM, name, fmt.Sprintf("vpc of subnet %s unreadable in database: %v", subnetName, err))
+			continue
+		}
+		checkVMTap(entries[prefix+"tap_id"], name, vpc, idx, n)
 	}
 
-	checkVMTap(db, name, vpc, n)
 	checkVMQemu(cfg, name, n)
 	checkUnit(kindVM, name, "metadata@"+name+".service", u, n)
 	checkUnit(kindVM, name, qemu.ScopeName(name), u, n)
 }
 
-func checkVMTap(db *badger.DB, name, vpc string, n notify.Notifier) {
-	raw, err := kv.GetFromDB(db, prefixVM+name+"/tap_id")
-	if err != nil {
-		n.Notify(kindVM, name, fmt.Sprintf("tap_id unreadable in database: %v", err))
+// nicIndexes retourne les index d'interface présents en base, triés.
+func nicIndexes(entries map[string]string, prefix string) []int {
+	seen := make(map[int]bool)
+	for key := range entries {
+		parts := strings.Split(strings.TrimPrefix(key, prefix), "/")
+		if len(parts) != 2 {
+			continue
+		}
+		if idx, err := strconv.Atoi(parts[0]); err == nil {
+			seen[idx] = true
+		}
+	}
+	indexes := make([]int, 0, len(seen))
+	for idx := range seen {
+		indexes = append(indexes, idx)
+	}
+	sort.Ints(indexes)
+	return indexes
+}
+
+func checkVMTap(raw, name, vpc string, idx int, n notify.Notifier) {
+	if raw == "" {
+		n.Notify(kindVM, name, fmt.Sprintf("interface %d has no tap_id in database", idx))
 		return
 	}
 	tapID, err := strconv.Atoi(raw)
 	if err != nil {
-		n.Notify(kindVM, name, fmt.Sprintf("invalid tap_id %q: %v", raw, err))
+		n.Notify(kindVM, name, fmt.Sprintf("interface %d has an invalid tap_id %q: %v", idx, raw, err))
 		return
 	}
 

internal/watchdog/check_vm_test.go

@@ -20,10 +20,11 @@ func testCfg(t *testing.T) *configuration.Config {
 func seedVM(t *testing.T, db *badger.DB, name, subnetName, vpc, tapID string) {
 	t.Helper()
 	seedResource(t, db, prefixVM, name, state.Running)
-	seedKV(t, db, prefixVM+name+"/subnet", subnetName)
+	seedKV(t, db, prefixVM+name+"/nic/0/subnet", subnetName)
+	seedKV(t, db, prefixVM+name+"/nic/0/primary", "true")
 	seedKV(t, db, prefixSubnet+subnetName+"/vpc", vpc)
 	if tapID != "" {
-		seedKV(t, db, prefixVM+name+"/tap_id", tapID)
+		seedKV(t, db, prefixVM+name+"/nic/0/tap_id", tapID)
 	}
 }
 
@@ -73,7 +74,7 @@ func TestCheckVMs_IgnoreLesEtatsNonRunning(t *testing.T) {
 	}
 }
 
-func TestCheckVMs_SubnetManquantEnBase(t *testing.T) {
+func TestCheckVMs_AucuneInterfaceEnBase(t *testing.T) {
 	db := newTestDB(t)
 	seedResource(t, db, prefixVM, "i-test1", state.Running)
 	r := &recorder{}
@@ -86,15 +87,16 @@ func TestCheckVMs_SubnetManquantEnBase(t *testing.T) {
 	if len(got) != 1 {
 		t.Fatalf("attendu 1 notification, obtenu %d : %v", len(got), got)
 	}
-	if !strings.Contains(got[0].problem, "subnet unreadable") {
-		t.Errorf("problem = %q, devrait porter sur le subnet", got[0].problem)
+	if !strings.Contains(got[0].problem, "no interface") {
+		t.Errorf("problem = %q, devrait signaler l'absence d'interface", got[0].problem)
 	}
 }
 
 func TestCheckVMs_VPCDuSubnetManquant(t *testing.T) {
 	db := newTestDB(t)
 	seedResource(t, db, prefixVM, "i-test1", state.Running)
-	seedKV(t, db, prefixVM+"i-test1/subnet", "br-000042")
+	seedKV(t, db, prefixVM+"i-test1/nic/0/subnet", "br-000042")
+	seedKV(t, db, prefixVM+"i-test1/nic/0/primary", "true")
 	r := &recorder{}
 
 	if err := CheckVMs(db, testCfg(t), newFakeUnits(), r); err != nil {
@@ -115,8 +117,8 @@ func TestCheckVMs_TapIDManquant(t *testing.T) {
 		t.Fatalf("erreur inattendue: %v", err)
 	}
 
-	if !r.hasProblemContaining("tap_id unreadable") {
-		t.Errorf("devrait signaler un tap_id illisible, obtenu %v", r.calls)
+	if !r.hasProblemContaining("has no tap_id") {
+		t.Errorf("devrait signaler un tap_id absent, obtenu %v", r.calls)
 	}
 }