drivers: Add Virtiofs mounts for vfkit and krunkit

Replace 9p mounts with virtiofs for vfkit and krunkit. Testing shows
that virtiofs mount is 23 times faster with krunkit, and 8 times faster
with vfkit.

vfkit and krunkit support multiple virtiofs mounts but minikube
--mount-* flags are not ready for multiple mounts. We have the same
issue with KIC drivers, supporting multiple mounts but using only one.
We hope to improve this in the next release.

Example usage:

    minikube start --mount-string ~/models:/mnt/models

The arguments are parsed and validated when configuring the driver, so
invalid arguments fail quickly without starting the driver. The
validated mounts are stored in the machine config:

    $ jq '.Driver.VirtiofsMounts' < ~/.minikube/machines/minikube/config.json
    [
      {
        "HostPath": "/Users/joe/models",
        "GuestPath": "/mnt/models",
        "Tag": "f845b54d-00e3-493d-9541-3b37490b96db"
      }
    ]

Minikube generates a new random UUID for every virtiofs mount to
identify the file system inside the guest. In krunkit and vfkit, every
mount is add as:

    --device virtio-fs,sharedDir=/host-path,mountTag=f845b54d-00e3-493d-9541-3b37490b96db

When the guest is started the shared directory is mounted via SSH using:

    sudo mkdir -p /mnt/models
    sudo mount -t virtiofs f845b54d-00e3-493d-9541-3b37490b96db /mnt/models

Example mount:

    $ minikube ssh findmnt /mnt/models
    TARGET      SOURCE                               FSTYPE   OPTIONS
    /mnt/models f845b54d-00e3-493d-9541-3b37490b96db virtiofs rw,relatime

More work is needed to add VirtioFS to qemu. I'm starting with vfkit and
krunkit since they have identical interface (krunkit was designed as
drop-in replacement for vfkit).

Author: nirs

pkg/drivers/krunkit/krunkit.go

@@ -42,6 +42,7 @@ import (
 
 	"k8s.io/klog/v2"
 	"k8s.io/minikube/pkg/drivers/common"
+	"k8s.io/minikube/pkg/drivers/common/virtiofs"
 	"k8s.io/minikube/pkg/drivers/common/vmnet"
 	"k8s.io/minikube/pkg/minikube/exit"
 	"k8s.io/minikube/pkg/minikube/firewall"
@@ -71,6 +72,7 @@ type Driver struct {
 	CPU            int
 	Memory         int
 	ExtraDisks     int
+	VirtiofsMounts []*virtiofs.Mount
 	MACAddress     string
 	VmnetHelper    vmnet.Helper
 }
@@ -207,8 +209,18 @@ func (d *Driver) Start() error {
 	}
 
 	log.Infof("Waiting for VM to start (ssh -p %d docker@%s)...", d.SSHPort, d.IPAddress)
+	if err := WaitForTCPWithDelay(fmt.Sprintf("%s:%d", d.IPAddress, d.SSHPort), time.Second); err != nil {
+		return err
+	}
+
+	if len(d.VirtiofsMounts) > 0 {
+		log.Infof("Setup virtiofs mounts ...")
+		if err := virtiofs.SetupMounts(d, d.VirtiofsMounts); err != nil {
+			return err
+		}
+	}
 
-	return WaitForTCPWithDelay(fmt.Sprintf("%s:%d", d.IPAddress, d.SSHPort), time.Second)
+	return nil
 }
 
 // startKrunkit starts the krunkit child process.
@@ -231,6 +243,11 @@ func (d *Driver) startKrunkit(socketPath string) error {
 			"--device", fmt.Sprintf("virtio-blk,path=%s", common.ExtraDiskPath(d.BaseDriver, i)))
 	}
 
+	for _, mount := range d.VirtiofsMounts {
+		args = append(args,
+			"--device", fmt.Sprintf("virtio-fs,sharedDir=%s,mountTag=%s", mount.HostPath, mount.Tag))
+	}
+
 	log.Debugf("executing: krunkit %s", strings.Join(args, " "))
 	cmd := exec.Command(driverName, args...)
 

pkg/drivers/vfkit/vfkit.go

@@ -44,6 +44,7 @@ import (
 
 	"k8s.io/klog/v2"
 	"k8s.io/minikube/pkg/drivers/common"
+	"k8s.io/minikube/pkg/drivers/common/virtiofs"
 	"k8s.io/minikube/pkg/drivers/common/vmnet"
 	"k8s.io/minikube/pkg/minikube/detect"
 	"k8s.io/minikube/pkg/minikube/exit"
@@ -72,6 +73,7 @@ type Driver struct {
 	CPU            int
 	Memory         int
 	ExtraDisks     int
+	VirtiofsMounts []*virtiofs.Mount
 	Network        string        // "", "nat", "vmnet-shared"
 	MACAddress     string        // For network=nat, network=""
 	VmnetHelper    *vmnet.Helper // For network=vmnet-shared
@@ -250,8 +252,18 @@ func (d *Driver) Start() error {
 	}
 
 	log.Infof("Waiting for VM to start (ssh -p %d docker@%s)...", d.SSHPort, d.IPAddress)
+	if err := WaitForTCPWithDelay(fmt.Sprintf("%s:%d", d.IPAddress, d.SSHPort), time.Second); err != nil {
+		return err
+	}
+
+	if len(d.VirtiofsMounts) > 0 {
+		log.Infof("Setup virtiofs mounts ...")
+		if err := virtiofs.SetupMounts(d, d.VirtiofsMounts); err != nil {
+			return err
+		}
+	}
 
-	return WaitForTCPWithDelay(fmt.Sprintf("%s:%d", d.IPAddress, d.SSHPort), time.Second)
+	return nil
 }
 
 // startVfkit starts the vfkit child process. If socketPath is not empty, vfkit
@@ -308,6 +320,12 @@ func (d *Driver) startVfkit(socketPath string) error {
 	startCmd = append(startCmd,
 		"--device", fmt.Sprintf("virtio-serial,logFilePath=%s", serialPath))
 
+	for _, mount := range d.VirtiofsMounts {
+		startCmd = append(startCmd,
+			"--device", fmt.Sprintf("virtio-fs,sharedDir=%s,mountTag=%s", mount.HostPath, mount.Tag))
+
+	}
+
 	log.Debugf("executing: vfkit %s", strings.Join(startCmd, " "))
 	os.Remove(d.sockfilePath())
 	cmd := exec.Command("vfkit", startCmd...)

pkg/minikube/driver/driver.go

@@ -228,6 +228,11 @@ func SupportsNetworkFlag(name string) bool {
 	return IsKIC(name) || IsKVM(name) || IsQEMU(name) || IsVFKit(name)
 }
 
+// SupportsVirtiofsMounts returns if driver supports virtiofs mounts
+func SupportsVirtiofsMounts(name string) bool {
+	return IsVFKit(name) || IsKrunkit(name)
+}
+
 // AllowsPreload returns if preload is allowed for the driver
 func AllowsPreload(driverName string) bool {
 	return !BareMetal(driverName) && !IsSSH(driverName)

pkg/minikube/node/config.go

@@ -73,7 +73,7 @@ func configureMounts(wg *sync.WaitGroup, cc config.ClusterConfig) {
 	wg.Add(1)
 	defer wg.Done()
 
-	if cc.MountString == "" || driver.IsKIC(cc.Driver) {
+	if cc.MountString == "" || driver.IsKIC(cc.Driver) || driver.SupportsVirtiofsMounts(cc.Driver) {
 		return
 	}
 

pkg/minikube/registry/drvs/krunkit/krunkit.go

@@ -28,6 +28,7 @@ import (
 	"github.com/docker/machine/libmachine/drivers"
 	"github.com/google/uuid"
 
+	"k8s.io/minikube/pkg/drivers/common/virtiofs"
 	"k8s.io/minikube/pkg/drivers/common/vmnet"
 	"k8s.io/minikube/pkg/drivers/krunkit"
 	"k8s.io/minikube/pkg/minikube/config"
@@ -65,6 +66,11 @@ func configure(cfg config.ClusterConfig, n config.Node) (interface{}, error) {
 		u = uuid.NewString()
 	}
 
+	mounts, err := virtiofs.ValidateMountString(cfg.MountString)
+	if err != nil {
+		return nil, err
+	}
+
 	return &krunkit.Driver{
 		BaseDriver: &drivers.BaseDriver{
 			MachineName: machineName,
@@ -76,6 +82,7 @@ func configure(cfg config.ClusterConfig, n config.Node) (interface{}, error) {
 		Memory:         cfg.Memory,
 		CPU:            cfg.CPUs,
 		ExtraDisks:     cfg.ExtraDisks,
+		VirtiofsMounts: mounts,
 		VmnetHelper: vmnet.Helper{
 			MachineDir:  filepath.Join(storePath, "machines", machineName),
 			InterfaceID: u,

pkg/minikube/registry/drvs/vfkit/vfkit.go

@@ -28,6 +28,7 @@ import (
 	"github.com/docker/machine/libmachine/drivers"
 	"github.com/google/uuid"
 
+	"k8s.io/minikube/pkg/drivers/common/virtiofs"
 	"k8s.io/minikube/pkg/drivers/common/vmnet"
 	"k8s.io/minikube/pkg/drivers/vfkit"
 	"k8s.io/minikube/pkg/minikube/config"
@@ -88,6 +89,11 @@ func configure(cfg config.ClusterConfig, n config.Node) (interface{}, error) {
 		return nil, fmt.Errorf("unsupported network: %q", cfg.Network)
 	}
 
+	mounts, err := virtiofs.ValidateMountString(cfg.MountString)
+	if err != nil {
+		return nil, err
+	}
+
 	return &vfkit.Driver{
 		BaseDriver: &drivers.BaseDriver{
 			MachineName: machineName,
@@ -99,6 +105,7 @@ func configure(cfg config.ClusterConfig, n config.Node) (interface{}, error) {
 		Memory:         cfg.Memory,
 		CPU:            cfg.CPUs,
 		ExtraDisks:     cfg.ExtraDisks,
+		VirtiofsMounts: mounts,
 		Network:        cfg.Network,
 		MACAddress:     mac,
 		VmnetHelper:    helper,