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qemu.go
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qemu.go
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package driver
import (
"encoding/json"
"fmt"
"log"
"os"
"os/exec"
"path/filepath"
"regexp"
"runtime"
"strings"
"time"
"github.com/hashicorp/go-plugin"
"github.com/hashicorp/nomad/client/allocdir"
"github.com/hashicorp/nomad/client/config"
"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/discover"
"github.com/hashicorp/nomad/helper/fields"
"github.com/hashicorp/nomad/nomad/structs"
"github.com/mitchellh/mapstructure"
)
var (
reQemuVersion = regexp.MustCompile(`version (\d[\.\d+]+)`)
)
const (
// The key populated in Node Attributes to indicate presence of the Qemu
// driver
qemuDriverAttr = "driver.qemu"
)
// 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
}
type QemuDriverConfig struct {
ImagePath string `mapstructure:"image_path"`
Accelerator string `mapstructure:"accelerator"`
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
allocDir *allocdir.AllocDir
killTimeout time.Duration
maxKillTimeout time.Duration
logger *log.Logger
version string
waitCh chan *dstructs.WaitResult
doneCh chan struct{}
}
// 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": &fields.FieldSchema{
Type: fields.TypeString,
Required: true,
},
"accelerator": &fields.FieldSchema{
Type: fields.TypeString,
},
"port_map": &fields.FieldSchema{
Type: fields.TypeArray,
},
"args": &fields.FieldSchema{
Type: fields.TypeArray,
},
},
}
if err := fd.Validate(); err != nil {
return err
}
return nil
}
func (d *QemuDriver) Abilities() DriverAbilities {
return DriverAbilities{
SendSignals: false,
}
}
func (d *QemuDriver) Fingerprint(cfg *config.Config, node *structs.Node) (bool, error) {
// Get the current status so that we can log any debug messages only if the
// state changes
_, currentlyEnabled := node.Attributes[qemuDriverAttr]
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 {
delete(node.Attributes, qemuDriverAttr)
return false, nil
}
out := strings.TrimSpace(string(outBytes))
matches := reQemuVersion.FindStringSubmatch(out)
if len(matches) != 2 {
delete(node.Attributes, qemuDriverAttr)
return false, fmt.Errorf("Unable to parse Qemu version string: %#v", matches)
}
if !currentlyEnabled {
d.logger.Printf("[DEBUG] driver.qemu: enabling driver")
}
node.Attributes[qemuDriverAttr] = "1"
node.Attributes["driver.qemu.version"] = matches[1]
return true, 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) (DriverHandle, 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")
}
// Get the image source
vmPath := driverConfig.ImagePath
if vmPath == "" {
return nil, fmt.Errorf("image_path must be set")
}
vmID := filepath.Base(vmPath)
// Get the tasks local directory.
taskDir, ok := ctx.AllocDir.TaskDirs[d.DriverContext.taskName]
if !ok {
return nil, fmt.Errorf("Could not find task directory for task: %v", d.DriverContext.taskName)
}
// Parse configuration arguments
// Create the base arguments
accelerator := "tcg"
if driverConfig.Accelerator != "" {
accelerator = driverConfig.Accelerator
}
// TODO: Check a lower bounds, e.g. the default 128 of Qemu
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",
}
// 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, 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(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].MapLabelToValues(nil)
for label, guest := range 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" {
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] Starting QemuVM command: %q", strings.Join(args, " "))
bin, err := discover.NomadExecutable()
if err != nil {
return nil, fmt.Errorf("unable to find the nomad binary: %v", err)
}
pluginLogFile := filepath.Join(taskDir, fmt.Sprintf("%s-executor.out", task.Name))
pluginConfig := &plugin.ClientConfig{
Cmd: exec.Command(bin, "executor", pluginLogFile),
}
exec, pluginClient, err := createExecutor(pluginConfig, d.config.LogOutput, d.config)
if err != nil {
return nil, err
}
executorCtx := &executor.ExecutorContext{
TaskEnv: d.taskEnv,
Driver: "qemu",
AllocDir: ctx.AllocDir,
AllocID: ctx.AllocID,
Task: task,
}
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] Started new QemuVM: %s", vmID)
// Create and Return Handle
maxKill := d.DriverContext.config.MaxKillTimeout
h := &qemuHandle{
pluginClient: pluginClient,
executor: exec,
userPid: ps.Pid,
allocDir: ctx.AllocDir,
killTimeout: GetKillTimeout(task.KillTimeout, maxKill),
maxKillTimeout: maxKill,
version: d.config.Version,
logger: d.logger,
doneCh: make(chan struct{}),
waitCh: make(chan *dstructs.WaitResult, 1),
}
if err := h.executor.SyncServices(consulContext(d.config, "")); err != nil {
h.logger.Printf("[ERR] driver.qemu: error registering services for task: %q: %v", task.Name, err)
}
go h.run()
return h, nil
}
type qemuId struct {
Version string
KillTimeout time.Duration
MaxKillTimeout time.Duration
UserPid int
PluginConfig *PluginReattachConfig
AllocDir *allocdir.AllocDir
}
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 '%s': %v", handleID, err)
}
pluginConfig := &plugin.ClientConfig{
Reattach: id.PluginConfig.PluginConfig(),
}
exec, pluginClient, err := createExecutor(pluginConfig, d.config.LogOutput, d.config)
if err != nil {
d.logger.Println("[ERR] driver.qemu: error connecting to plugin so destroying plugin pid and user pid")
if e := destroyPlugin(id.PluginConfig.Pid, id.UserPid); e != nil {
d.logger.Printf("[ERR] driver.qemu: error destroying plugin and userpid: %v", 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,
allocDir: id.AllocDir,
logger: d.logger,
killTimeout: id.KillTimeout,
maxKillTimeout: id.MaxKillTimeout,
version: id.Version,
doneCh: make(chan struct{}),
waitCh: make(chan *dstructs.WaitResult, 1),
}
if err := h.executor.SyncServices(consulContext(d.config, "")); err != nil {
h.logger.Printf("[ERR] driver.qemu: error registering services: %v", err)
}
go h.run()
return h, 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,
AllocDir: h.allocDir,
}
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) Signal(s os.Signal) error {
return fmt.Errorf("Qemu driver can't send signals")
}
// TODO: allow a 'shutdown_command' that can be executed over a ssh connection
// to the VM
func (h *qemuHandle) Kill() error {
if err := h.executor.ShutDown(); err != nil {
if h.pluginClient.Exited() {
return nil
}
return fmt.Errorf("executor Shutdown failed: %v", err)
}
select {
case <-h.doneCh:
return nil
case <-time.After(h.killTimeout):
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: %v", e)
}
if e := h.allocDir.UnmountAll(); e != nil {
h.logger.Printf("[ERR] driver.qemu: unmounting dev,proc and alloc dirs failed: %v", e)
}
}
close(h.doneCh)
// Remove services
if err := h.executor.DeregisterServices(); err != nil {
h.logger.Printf("[ERR] driver.qemu: failed to deregister services: %v", err)
}
// 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)
}