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qemu.go
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qemu.go
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package driver
import (
"context"
"encoding/json"
"errors"
"fmt"
"log"
"net"
"os"
"os/exec"
"path/filepath"
"regexp"
"runtime"
"strings"
"time"
"github.com/coreos/go-semver/semver"
plugin "github.com/hashicorp/go-plugin"
"github.com/hashicorp/nomad/client/driver/executor"
dstructs "github.com/hashicorp/nomad/client/driver/structs"
"github.com/hashicorp/nomad/client/fingerprint"
cstructs "github.com/hashicorp/nomad/client/structs"
"github.com/hashicorp/nomad/helper/fields"
"github.com/hashicorp/nomad/nomad/structs"
"github.com/mitchellh/mapstructure"
)
var (
reQemuVersion = regexp.MustCompile(`version (\d[\.\d+]+)`)
// Prior to qemu 2.10.1, monitor socket paths are truncated to 108 bytes.
// We should consider this if driver.qemu.version is < 2.10.1 and the
// generated monitor path is too long.
//
// Relevant fix is here:
// https://github.com/qemu/qemu/commit/ad9579aaa16d5b385922d49edac2c96c79bcfb6
qemuVersionLongSocketPathFix = semver.New("2.10.1")
)
const (
// The key populated in Node Attributes to indicate presence of the Qemu driver
qemuDriverAttr = "driver.qemu"
qemuDriverVersionAttr = "driver.qemu.version"
// Represents an ACPI shutdown request to the VM (emulates pressing a physical power button)
// Reference: https://en.wikibooks.org/wiki/QEMU/Monitor
qemuGracefulShutdownMsg = "system_powerdown\n"
qemuMonitorSocketName = "qemu-monitor.sock"
// Maximum socket path length prior to qemu 2.10.1
qemuLegacyMaxMonitorPathLen = 108
)
// QemuDriver is a driver for running images via Qemu
// We attempt to chose sane defaults for now, with more configuration available
// planned in the future
type QemuDriver struct {
DriverContext
fingerprint.StaticFingerprinter
driverConfig *QemuDriverConfig
}
type QemuDriverConfig struct {
ImagePath string `mapstructure:"image_path"`
Accelerator string `mapstructure:"accelerator"`
GracefulShutdown bool `mapstructure:"graceful_shutdown"`
PortMap []map[string]int `mapstructure:"port_map"` // A map of host port labels and to guest ports.
Args []string `mapstructure:"args"` // extra arguments to qemu executable
}
// qemuHandle is returned from Start/Open as a handle to the PID
type qemuHandle struct {
pluginClient *plugin.Client
userPid int
executor executor.Executor
monitorPath string
killTimeout time.Duration
maxKillTimeout time.Duration
logger *log.Logger
version string
waitCh chan *dstructs.WaitResult
doneCh chan struct{}
}
// getMonitorPath is used to determine whether a qemu monitor socket can be
// safely created and accessed in the task directory by the version of qemu
// present on the host. If it is safe to use, the socket's full path is
// returned along with a nil error. Otherwise, an empty string is returned
// along with a descriptive error.
func (d *QemuDriver) getMonitorPath(dir string) (string, error) {
var longPathSupport bool
currentQemuVer := d.DriverContext.node.Attributes[qemuDriverVersionAttr]
currentQemuSemver := semver.New(currentQemuVer)
if currentQemuSemver.LessThan(*qemuVersionLongSocketPathFix) {
longPathSupport = false
d.logger.Printf("[DEBUG] driver.qemu: long socket paths are not available in this version of QEMU (%s)", currentQemuVer)
} else {
longPathSupport = true
d.logger.Printf("[DEBUG] driver.qemu: long socket paths available in this version of QEMU (%s)", currentQemuVer)
}
fullSocketPath := fmt.Sprintf("%s/%s", dir, qemuMonitorSocketName)
if len(fullSocketPath) > qemuLegacyMaxMonitorPathLen && longPathSupport == false {
return "", fmt.Errorf("monitor path is too long for this version of qemu")
}
return fullSocketPath, nil
}
// NewQemuDriver is used to create a new exec driver
func NewQemuDriver(ctx *DriverContext) Driver {
return &QemuDriver{DriverContext: *ctx}
}
// Validate is used to validate the driver configuration
func (d *QemuDriver) Validate(config map[string]interface{}) error {
fd := &fields.FieldData{
Raw: config,
Schema: map[string]*fields.FieldSchema{
"image_path": {
Type: fields.TypeString,
Required: true,
},
"accelerator": {
Type: fields.TypeString,
},
"graceful_shutdown": {
Type: fields.TypeBool,
Required: false,
},
"port_map": {
Type: fields.TypeArray,
},
"args": {
Type: fields.TypeArray,
},
},
}
if err := fd.Validate(); err != nil {
return err
}
return nil
}
func (d *QemuDriver) Abilities() DriverAbilities {
return DriverAbilities{
SendSignals: false,
Exec: false,
}
}
func (d *QemuDriver) FSIsolation() cstructs.FSIsolation {
return cstructs.FSIsolationImage
}
func (d *QemuDriver) Fingerprint(req *cstructs.FingerprintRequest, resp *cstructs.FingerprintResponse) error {
bin := "qemu-system-x86_64"
if runtime.GOOS == "windows" {
// On windows, the "qemu-system-x86_64" command does not respond to the
// version flag.
bin = "qemu-img"
}
outBytes, err := exec.Command(bin, "--version").Output()
if err != nil {
// return no error, as it isn't an error to not find qemu, it just means we
// can't use it.
return nil
}
out := strings.TrimSpace(string(outBytes))
matches := reQemuVersion.FindStringSubmatch(out)
if len(matches) != 2 {
resp.RemoveAttribute(qemuDriverAttr)
return fmt.Errorf("Unable to parse Qemu version string: %#v", matches)
}
currentQemuVersion := matches[1]
resp.AddAttribute(qemuDriverAttr, "1")
resp.AddAttribute(qemuDriverVersionAttr, currentQemuVersion)
resp.Detected = true
return nil
}
func (d *QemuDriver) Prestart(_ *ExecContext, task *structs.Task) (*PrestartResponse, error) {
var driverConfig QemuDriverConfig
if err := mapstructure.WeakDecode(task.Config, &driverConfig); err != nil {
return nil, err
}
if len(driverConfig.PortMap) > 1 {
return nil, fmt.Errorf("Only one port_map block is allowed in the qemu driver config")
}
d.driverConfig = &driverConfig
r := NewPrestartResponse()
if len(driverConfig.PortMap) == 1 {
r.Network = &cstructs.DriverNetwork{
PortMap: driverConfig.PortMap[0],
}
}
return r, nil
}
// Run an existing Qemu image. Start() will pull down an existing, valid Qemu
// image and save it to the Drivers Allocation Dir
func (d *QemuDriver) Start(ctx *ExecContext, task *structs.Task) (*StartResponse, error) {
// Get the image source
vmPath := d.driverConfig.ImagePath
if vmPath == "" {
return nil, fmt.Errorf("image_path must be set")
}
vmID := filepath.Base(vmPath)
// Parse configuration arguments
// Create the base arguments
accelerator := "tcg"
if d.driverConfig.Accelerator != "" {
accelerator = d.driverConfig.Accelerator
}
if task.Resources.MemoryMB < 128 || task.Resources.MemoryMB > 4000000 {
return nil, fmt.Errorf("Qemu memory assignment out of bounds")
}
mem := fmt.Sprintf("%dM", task.Resources.MemoryMB)
absPath, err := GetAbsolutePath("qemu-system-x86_64")
if err != nil {
return nil, err
}
args := []string{
absPath,
"-machine", "type=pc,accel=" + accelerator,
"-name", vmID,
"-m", mem,
"-drive", "file=" + vmPath,
"-nographic",
}
var monitorPath string
if d.driverConfig.GracefulShutdown {
if runtime.GOOS == "windows" {
return nil, errors.New("QEMU graceful shutdown is unsupported on the Windows platform")
}
// This socket will be used to manage the virtual machine (for example,
// to perform graceful shutdowns)
monitorPath, err = d.getMonitorPath(ctx.TaskDir.Dir)
if err != nil {
d.logger.Printf("[ERR] driver.qemu: could not get qemu monitor path: %s", err)
return nil, err
}
d.logger.Printf("[DEBUG] driver.qemu: got monitor path OK: %s", monitorPath)
args = append(args, "-monitor", fmt.Sprintf("unix:%s,server,nowait", monitorPath))
}
// Add pass through arguments to qemu executable. A user can specify
// these arguments in driver task configuration. These arguments are
// passed directly to the qemu driver as command line options.
// For example, args = [ "-nodefconfig", "-nodefaults" ]
// This will allow a VM with embedded configuration to boot successfully.
args = append(args, d.driverConfig.Args...)
// Check the Resources required Networks to add port mappings. If no resources
// are required, we assume the VM is a purely compute job and does not require
// the outside world to be able to reach it. VMs ran without port mappings can
// still reach out to the world, but without port mappings it is effectively
// firewalled
protocols := []string{"udp", "tcp"}
if len(task.Resources.Networks) > 0 && len(d.driverConfig.PortMap) == 1 {
// Loop through the port map and construct the hostfwd string, to map
// reserved ports to the ports listenting in the VM
// Ex: hostfwd=tcp::22000-:22,hostfwd=tcp::80-:8080
var forwarding []string
taskPorts := task.Resources.Networks[0].PortLabels()
for label, guest := range d.driverConfig.PortMap[0] {
host, ok := taskPorts[label]
if !ok {
return nil, fmt.Errorf("Unknown port label %q", label)
}
for _, p := range protocols {
forwarding = append(forwarding, fmt.Sprintf("hostfwd=%s::%d-:%d", p, host, guest))
}
}
if len(forwarding) != 0 {
args = append(args,
"-netdev",
fmt.Sprintf("user,id=user.0,%s", strings.Join(forwarding, ",")),
"-device", "virtio-net,netdev=user.0",
)
}
}
// If using KVM, add optimization args
if accelerator == "kvm" {
if runtime.GOOS == "windows" {
return nil, errors.New("KVM accelerator is unsupported on the Windows platform")
}
args = append(args,
"-enable-kvm",
"-cpu", "host",
// Do we have cores information available to the Driver?
// "-smp", fmt.Sprintf("%d", cores),
)
}
d.logger.Printf("[DEBUG] driver.qemu: starting QemuVM command: %q", strings.Join(args, " "))
pluginLogFile := filepath.Join(ctx.TaskDir.Dir, "executor.out")
executorConfig := &dstructs.ExecutorConfig{
LogFile: pluginLogFile,
LogLevel: d.config.LogLevel,
}
exec, pluginClient, err := createExecutor(d.config.LogOutput, d.config, executorConfig)
if err != nil {
return nil, err
}
executorCtx := &executor.ExecutorContext{
TaskEnv: ctx.TaskEnv,
Driver: "qemu",
Task: task,
TaskDir: ctx.TaskDir.Dir,
LogDir: ctx.TaskDir.LogDir,
}
if err := exec.SetContext(executorCtx); err != nil {
pluginClient.Kill()
return nil, fmt.Errorf("failed to set executor context: %v", err)
}
execCmd := &executor.ExecCommand{
Cmd: args[0],
Args: args[1:],
User: task.User,
}
ps, err := exec.LaunchCmd(execCmd)
if err != nil {
pluginClient.Kill()
return nil, err
}
d.logger.Printf("[INFO] driver.qemu: started new QemuVM: %s", vmID)
// Create and Return Handle
maxKill := d.DriverContext.config.MaxKillTimeout
h := &qemuHandle{
pluginClient: pluginClient,
executor: exec,
userPid: ps.Pid,
killTimeout: GetKillTimeout(task.KillTimeout, maxKill),
maxKillTimeout: maxKill,
monitorPath: monitorPath,
version: d.config.Version.VersionNumber(),
logger: d.logger,
doneCh: make(chan struct{}),
waitCh: make(chan *dstructs.WaitResult, 1),
}
go h.run()
resp := &StartResponse{Handle: h}
if len(d.driverConfig.PortMap) == 1 {
resp.Network = &cstructs.DriverNetwork{
PortMap: d.driverConfig.PortMap[0],
}
}
return resp, nil
}
type qemuId struct {
Version string
KillTimeout time.Duration
MaxKillTimeout time.Duration
UserPid int
PluginConfig *PluginReattachConfig
}
func (d *QemuDriver) Open(ctx *ExecContext, handleID string) (DriverHandle, error) {
id := &qemuId{}
if err := json.Unmarshal([]byte(handleID), id); err != nil {
return nil, fmt.Errorf("Failed to parse handle %q: %v", handleID, err)
}
pluginConfig := &plugin.ClientConfig{
Reattach: id.PluginConfig.PluginConfig(),
}
exec, pluginClient, err := createExecutorWithConfig(pluginConfig, d.config.LogOutput)
if err != nil {
d.logger.Printf("[ERR] driver.qemu: error connecting to plugin so destroying plugin pid %d and user pid %d", id.PluginConfig.Pid, id.UserPid)
if e := destroyPlugin(id.PluginConfig.Pid, id.UserPid); e != nil {
d.logger.Printf("[ERR] driver.qemu: error destroying plugin pid %d and userpid %d: %v", id.PluginConfig.Pid, id.UserPid, e)
}
return nil, fmt.Errorf("error connecting to plugin: %v", err)
}
ver, _ := exec.Version()
d.logger.Printf("[DEBUG] driver.qemu: version of executor: %v", ver.Version)
// Return a driver handle
h := &qemuHandle{
pluginClient: pluginClient,
executor: exec,
userPid: id.UserPid,
logger: d.logger,
killTimeout: id.KillTimeout,
maxKillTimeout: id.MaxKillTimeout,
version: id.Version,
doneCh: make(chan struct{}),
waitCh: make(chan *dstructs.WaitResult, 1),
}
go h.run()
return h, nil
}
func (d *QemuDriver) Cleanup(*ExecContext, *CreatedResources) error { return nil }
func (h *qemuHandle) ID() string {
id := qemuId{
Version: h.version,
KillTimeout: h.killTimeout,
MaxKillTimeout: h.maxKillTimeout,
PluginConfig: NewPluginReattachConfig(h.pluginClient.ReattachConfig()),
UserPid: h.userPid,
}
data, err := json.Marshal(id)
if err != nil {
h.logger.Printf("[ERR] driver.qemu: failed to marshal ID to JSON: %s", err)
}
return string(data)
}
func (h *qemuHandle) WaitCh() chan *dstructs.WaitResult {
return h.waitCh
}
func (h *qemuHandle) Update(task *structs.Task) error {
// Store the updated kill timeout.
h.killTimeout = GetKillTimeout(task.KillTimeout, h.maxKillTimeout)
h.executor.UpdateTask(task)
// Update is not possible
return nil
}
func (h *qemuHandle) Exec(ctx context.Context, cmd string, args []string) ([]byte, int, error) {
return nil, 0, fmt.Errorf("Qemu driver can't execute commands")
}
func (h *qemuHandle) Signal(s os.Signal) error {
return fmt.Errorf("Qemu driver can't send signals")
}
func (h *qemuHandle) Kill() error {
gracefulShutdownSent := false
// Attempt a graceful shutdown only if it was configured in the job
if h.monitorPath != "" {
if err := sendQemuShutdown(h.logger, h.monitorPath, h.userPid); err == nil {
gracefulShutdownSent = true
} else {
h.logger.Printf("[DEBUG] driver.qemu: error sending graceful shutdown for user process pid %d: %s", h.userPid, err)
}
}
// If Nomad did not send a graceful shutdown signal, issue an interrupt to
// the qemu process as a last resort
if gracefulShutdownSent == false {
h.logger.Printf("[DEBUG] driver.qemu: graceful shutdown is not enabled, sending an interrupt signal to pid: %d", h.userPid)
if err := h.executor.ShutDown(); err != nil {
if h.pluginClient.Exited() {
return nil
}
return fmt.Errorf("executor Shutdown failed: %v", err)
}
}
// If the qemu process exits before the kill timeout is reached, doneChan
// will close and we'll exit without an error. If it takes too long, the
// timer will fire and we'll attempt to kill the process.
select {
case <-h.doneCh:
return nil
case <-time.After(h.killTimeout):
h.logger.Printf("[DEBUG] driver.qemu: kill timeout of %s exceeded for user process pid %d", h.killTimeout.String(), h.userPid)
if h.pluginClient.Exited() {
return nil
}
if err := h.executor.Exit(); err != nil {
return fmt.Errorf("executor Exit failed: %v", err)
}
return nil
}
}
func (h *qemuHandle) Stats() (*cstructs.TaskResourceUsage, error) {
return h.executor.Stats()
}
func (h *qemuHandle) run() {
ps, werr := h.executor.Wait()
if ps.ExitCode == 0 && werr != nil {
if e := killProcess(h.userPid); e != nil {
h.logger.Printf("[ERR] driver.qemu: error killing user process pid %d: %v", h.userPid, e)
}
}
close(h.doneCh)
// Exit the executor
h.executor.Exit()
h.pluginClient.Kill()
// Send the results
h.waitCh <- &dstructs.WaitResult{ExitCode: ps.ExitCode, Signal: ps.Signal, Err: werr}
close(h.waitCh)
}
// sendQemuShutdown attempts to issue an ACPI power-off command via the qemu
// monitor
func sendQemuShutdown(logger *log.Logger, monitorPath string, userPid int) error {
if monitorPath == "" {
return errors.New("monitorPath not set")
}
monitorSocket, err := net.Dial("unix", monitorPath)
if err != nil {
logger.Printf("[WARN] driver.qemu: could not connect to qemu monitor %q for user process pid %d: %s", monitorPath, userPid, err)
return err
}
defer monitorSocket.Close()
logger.Printf("[DEBUG] driver.qemu: sending graceful shutdown command to qemu monitor socket %q for user process pid %d", monitorPath, userPid)
_, err = monitorSocket.Write([]byte(qemuGracefulShutdownMsg))
if err != nil {
logger.Printf("[WARN] driver.qemu: failed to send shutdown message %q to monitor socket %q for user process pid %d: %s", qemuGracefulShutdownMsg, monitorPath, userPid, err)
}
return err
}