Golang getter.GetArtifact函數代碼示例

func (d *JavaDriver) Start(ctx *ExecContext, task *structs.Task) (DriverHandle, error) {
	var driverConfig JavaDriverConfig
	if err := mapstructure.WeakDecode(task.Config, &driverConfig); err != nil {
		return nil, err
	}
	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)
	}

	// Proceed to download an artifact to be executed.
	path, err := getter.GetArtifact(
		taskDir,
		driverConfig.ArtifactSource,
		driverConfig.Checksum,
		d.logger,
	)
	if err != nil {
		return nil, err
	}

	jarName := filepath.Base(path)

	args := []string{}
	// Look for jvm options
	if len(driverConfig.JvmOpts) != 0 {
		d.logger.Printf("[DEBUG] driver.java: found JVM options: %s", driverConfig.JvmOpts)
		args = append(args, driverConfig.JvmOpts...)
	}

	// Build the argument list.
	args = append(args, "-jar", jarName)
	if len(driverConfig.Args) != 0 {
		args = append(args, driverConfig.Args...)
	}

	// Setup the command
	// Assumes Java is in the $PATH, but could probably be detected
	execCtx := executor.NewExecutorContext(d.taskEnv)
	cmd := executor.Command(execCtx, "java", args...)

	// Populate environment variables
	cmd.Command().Env = d.taskEnv.EnvList()

	if err := cmd.Limit(task.Resources); err != nil {
		return nil, fmt.Errorf("failed to constrain resources: %s", err)
	}

	if err := cmd.ConfigureTaskDir(d.taskName, ctx.AllocDir); err != nil {
		return nil, fmt.Errorf("failed to configure task directory: %v", err)
	}

	if err := cmd.Start(); err != nil {
		return nil, fmt.Errorf("failed to start source: %v", err)
	}

	// Return a driver handle
	h := &javaHandle{
		cmd:         cmd,
		killTimeout: d.DriverContext.KillTimeout(task),
		logger:      d.logger,
		doneCh:      make(chan struct{}),
		waitCh:      make(chan *cstructs.WaitResult, 1),
	}

	go h.run()
	return h, nil
}

func (d *RawExecDriver) Start(ctx *ExecContext, task *structs.Task) (DriverHandle, error) {
	var driverConfig ExecDriverConfig
	if err := mapstructure.WeakDecode(task.Config, &driverConfig); err != nil {
		return nil, err
	}
	// Get the tasks local directory.
	taskName := d.DriverContext.taskName
	taskDir, ok := ctx.AllocDir.TaskDirs[taskName]
	if !ok {
		return nil, fmt.Errorf("Could not find task directory for task: %v", d.DriverContext.taskName)
	}

	// Get the command to be ran
	command := driverConfig.Command
	if err := validateCommand(command, "args"); err != nil {
		return nil, err
	}

	// Check if an artificat is specified and attempt to download it
	source, ok := task.Config["artifact_source"]
	if ok && source != "" {
		// Proceed to download an artifact to be executed.
		_, err := getter.GetArtifact(
			taskDir,
			driverConfig.ArtifactSource,
			driverConfig.Checksum,
			d.logger,
		)
		if err != nil {
			return nil, err
		}
	}

	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,
		AllocDir:      ctx.AllocDir,
		TaskName:      task.Name,
		TaskResources: task.Resources,
		LogConfig:     task.LogConfig,
	}
	ps, err := exec.LaunchCmd(&executor.ExecCommand{Cmd: command, Args: driverConfig.Args}, executorCtx)
	if err != nil {
		pluginClient.Kill()
		return nil, fmt.Errorf("error starting process via the plugin: %v", err)
	}
	d.logger.Printf("[DEBUG] driver.raw_exec: started process with pid: %v", ps.Pid)

	// Return a driver handle
	h := &rawExecHandle{
		pluginClient: pluginClient,
		executor:     exec,
		userPid:      ps.Pid,
		killTimeout:  d.DriverContext.KillTimeout(task),
		allocDir:     ctx.AllocDir,
		version:      d.config.Version,
		logger:       d.logger,
		doneCh:       make(chan struct{}),
		waitCh:       make(chan *cstructs.WaitResult, 1),
	}
	go h.run()
	return h, 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
	source, ok := task.Config["artifact_source"]
	if !ok || source == "" {
		return nil, fmt.Errorf("Missing source image Qemu driver")
	}

	// Qemu defaults to 128M of RAM for a given VM. Instead, we force users to
	// supply a memory size in the tasks resources
	if task.Resources == nil || task.Resources.MemoryMB == 0 {
		return nil, fmt.Errorf("Missing required Task Resource: Memory")
	}

	// 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)
	}

	// Proceed to download an artifact to be executed.
	vmPath, err := getter.GetArtifact(
		filepath.Join(taskDir, allocdir.TaskLocal),
		driverConfig.ArtifactSource,
		driverConfig.Checksum,
		d.logger,
	)
	if err != nil {
		return nil, err
	}

	vmID := filepath.Base(vmPath)

	// 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)

	args := []string{
		"qemu-system-x86_64",
		"-machine", "type=pc,accel=" + accelerator,
		"-name", vmID,
		"-m", mem,
		"-drive", "file=" + vmPath,
		"-nodefconfig",
		"-nodefaults",
		"-nographic",
	}

	// 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",
//.........這裏部分代碼省略.........

func (r *TaskRunner) run() {
	// Predeclare things so we an jump to the RESTART
	var handleEmpty bool

	for {
		// Download the task's artifacts
		if !r.artifactsDownloaded && len(r.task.Artifacts) > 0 {
			r.setState(structs.TaskStatePending, structs.NewTaskEvent(structs.TaskDownloadingArtifacts))
			taskDir, ok := r.ctx.AllocDir.TaskDirs[r.task.Name]
			if !ok {
				err := fmt.Errorf("task directory couldn't be found")
				r.setState(structs.TaskStateDead, structs.NewTaskEvent(structs.TaskDriverFailure).SetDriverError(err))
				r.logger.Printf("[ERR] client: task directory for alloc %q task %q couldn't be found", r.alloc.ID, r.task.Name)
				r.restartTracker.SetStartError(err)
				goto RESTART
			}

			for _, artifact := range r.task.Artifacts {
				if err := getter.GetArtifact(r.taskEnv, artifact, taskDir, r.logger); err != nil {
					r.setState(structs.TaskStateDead,
						structs.NewTaskEvent(structs.TaskArtifactDownloadFailed).SetDownloadError(err))
					r.restartTracker.SetStartError(cstructs.NewRecoverableError(err, true))
					goto RESTART
				}
			}

			r.artifactsDownloaded = true
		}

		// Start the task if not yet started or it is being forced. This logic
		// is necessary because in the case of a restore the handle already
		// exists.
		r.handleLock.Lock()
		handleEmpty = r.handle == nil
		r.handleLock.Unlock()
		if handleEmpty {
			startErr := r.startTask()
			r.restartTracker.SetStartError(startErr)
			if startErr != nil {
				r.setState(structs.TaskStateDead, structs.NewTaskEvent(structs.TaskDriverFailure).SetDriverError(startErr))
				goto RESTART
			}
		}

		// Mark the task as started
		r.setState(structs.TaskStateRunning, structs.NewTaskEvent(structs.TaskStarted))

		// Wait for updates
	WAIT:
		for {
			select {
			case waitRes := <-r.handle.WaitCh():
				if waitRes == nil {
					panic("nil wait")
				}

				// Log whether the task was successful or not.
				r.restartTracker.SetWaitResult(waitRes)
				r.setState(structs.TaskStateDead, r.waitErrorToEvent(waitRes))
				if !waitRes.Successful() {
					r.logger.Printf("[INFO] client: task %q for alloc %q failed: %v", r.task.Name, r.alloc.ID, waitRes)
				} else {
					r.logger.Printf("[INFO] client: task %q for alloc %q completed successfully", r.task.Name, r.alloc.ID)
				}

				break WAIT
			case update := <-r.updateCh:
				if err := r.handleUpdate(update); err != nil {
					r.logger.Printf("[ERR] client: update to task %q failed: %v", r.task.Name, err)
				}
			case <-r.destroyCh:
				// Kill the task using an exponential backoff in-case of failures.
				destroySuccess, err := r.handleDestroy()
				if !destroySuccess {
					// We couldn't successfully destroy the resource created.
					r.logger.Printf("[ERR] client: failed to kill task %q. Resources may have been leaked: %v", r.task.Name, err)
				}

				// Store that the task has been destroyed and any associated error.
				r.setState(structs.TaskStateDead, structs.NewTaskEvent(structs.TaskKilled).SetKillError(err))
				return
			}
		}

	RESTART:
		state, when := r.restartTracker.GetState()
		r.restartTracker.SetStartError(nil).SetWaitResult(nil)
		reason := r.restartTracker.GetReason()
		switch state {
		case structs.TaskNotRestarting, structs.TaskTerminated:
			r.logger.Printf("[INFO] client: Not restarting task: %v for alloc: %v ", r.task.Name, r.alloc.ID)
			if state == structs.TaskNotRestarting {
				r.setState(structs.TaskStateDead,
					structs.NewTaskEvent(structs.TaskNotRestarting).
						SetRestartReason(reason))
			}
			return
		case structs.TaskRestarting:
			r.logger.Printf("[INFO] client: Restarting task %q for alloc %q in %v", r.task.Name, r.alloc.ID, when)
			r.setState(structs.TaskStatePending,
//.........這裏部分代碼省略.........

func (d *RawExecDriver) Start(ctx *ExecContext, task *structs.Task) (DriverHandle, error) {
	var driverConfig ExecDriverConfig
	if err := mapstructure.WeakDecode(task.Config, &driverConfig); err != nil {
		return nil, err
	}
	// Get the tasks local directory.
	taskName := d.DriverContext.taskName
	taskDir, ok := ctx.AllocDir.TaskDirs[taskName]
	if !ok {
		return nil, fmt.Errorf("Could not find task directory for task: %v", d.DriverContext.taskName)
	}

	// Get the command to be ran
	command := driverConfig.Command
	if command == "" {
		return nil, fmt.Errorf("missing command for Raw Exec driver")
	}

	// Check if an artificat is specified and attempt to download it
	source, ok := task.Config["artifact_source"]
	if ok && source != "" {
		// Proceed to download an artifact to be executed.
		_, err := getter.GetArtifact(
			filepath.Join(taskDir, allocdir.TaskLocal),
			driverConfig.ArtifactSource,
			driverConfig.Checksum,
			d.logger,
		)
		if err != nil {
			return nil, err
		}
	}

	// Setup the command
	execCtx := executor.NewExecutorContext(d.taskEnv)
	cmd := executor.NewBasicExecutor(execCtx)
	executor.SetCommand(cmd, command, driverConfig.Args)
	if err := cmd.Limit(task.Resources); err != nil {
		return nil, fmt.Errorf("failed to constrain resources: %s", err)
	}

	// Populate environment variables
	cmd.Command().Env = d.taskEnv.EnvList()

	if err := cmd.ConfigureTaskDir(d.taskName, ctx.AllocDir); err != nil {
		return nil, fmt.Errorf("failed to configure task directory: %v", err)
	}

	if err := cmd.Start(); err != nil {
		return nil, fmt.Errorf("failed to start command: %v", err)
	}

	// Return a driver handle
	h := &execHandle{
		cmd:         cmd,
		killTimeout: d.DriverContext.KillTimeout(task),
		logger:      d.logger,
		doneCh:      make(chan struct{}),
		waitCh:      make(chan *cstructs.WaitResult, 1),
	}
	go h.run()
	return h, nil
}

// prestart handles life-cycle tasks that occur before the task has started.
func (r *TaskRunner) prestart(resultCh chan bool) {

	if r.task.Vault != nil {
		// Wait for the token
		r.logger.Printf("[DEBUG] client: waiting for Vault token for task %v in alloc %q", r.task.Name, r.alloc.ID)
		tokenCh := r.vaultFuture.Wait()
		select {
		case <-tokenCh:
		case <-r.waitCh:
			resultCh <- false
			return
		}
		r.logger.Printf("[DEBUG] client: retrieved Vault token for task %v in alloc %q", r.task.Name, r.alloc.ID)
	}

	if err := r.setTaskEnv(); err != nil {
		r.setState(
			structs.TaskStateDead,
			structs.NewTaskEvent(structs.TaskSetupFailure).SetSetupError(err).SetFailsTask())
		resultCh <- false
		return
	}

	for {
		// Download the task's artifacts
		if !r.artifactsDownloaded && len(r.task.Artifacts) > 0 {
			r.setState(structs.TaskStatePending, structs.NewTaskEvent(structs.TaskDownloadingArtifacts))
			for _, artifact := range r.task.Artifacts {
				if err := getter.GetArtifact(r.getTaskEnv(), artifact, r.taskDir); err != nil {
					wrapped := fmt.Errorf("failed to download artifact %q: %v", artifact.GetterSource, err)
					r.setState(structs.TaskStatePending,
						structs.NewTaskEvent(structs.TaskArtifactDownloadFailed).SetDownloadError(wrapped))
					r.restartTracker.SetStartError(structs.NewRecoverableError(wrapped, true))
					goto RESTART
				}
			}

			r.artifactsDownloaded = true
		}

		// We don't have to wait for any template
		if len(r.task.Templates) == 0 {
			// Send the start signal
			select {
			case r.startCh <- struct{}{}:
			default:
			}

			resultCh <- true
			return
		}

		// Build the template manager
		if r.templateManager == nil {
			var err error
			r.templateManager, err = NewTaskTemplateManager(r, r.task.Templates,
				r.config, r.vaultFuture.Get(), r.taskDir, r.getTaskEnv())
			if err != nil {
				err := fmt.Errorf("failed to build task's template manager: %v", err)
				r.setState(structs.TaskStateDead, structs.NewTaskEvent(structs.TaskSetupFailure).SetSetupError(err).SetFailsTask())
				r.logger.Printf("[ERR] client: alloc %q, task %q %v", r.alloc.ID, r.task.Name, err)
				resultCh <- false
				return
			}
		}

		// Block for consul-template
		// TODO Hooks should register themselves as blocking and then we can
		// perioidcally enumerate what we are still blocked on
		select {
		case <-r.unblockCh:
			// Send the start signal
			select {
			case r.startCh <- struct{}{}:
			default:
			}

			resultCh <- true
			return
		case <-r.waitCh:
			// The run loop has exited so exit too
			resultCh <- false
			return
		}

	RESTART:
		restart := r.shouldRestart()
		if !restart {
			resultCh <- false
			return
		}
	}
}

func (d *JavaDriver) Start(ctx *ExecContext, task *structs.Task) (DriverHandle, error) {
	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)
	}

	// Proceed to download an artifact to be executed.
	path, err := getter.GetArtifact(
		filepath.Join(taskDir, allocdir.TaskLocal),
		task.Config["artifact_source"],
		task.Config["checksum"],
		d.logger,
	)
	if err != nil {
		return nil, err
	}

	jarName := filepath.Base(path)

	// Get the environment variables.
	envVars := TaskEnvironmentVariables(ctx, task)

	args := []string{}
	// Look for jvm options
	jvm_options, ok := task.Config["jvm_options"]
	if ok && jvm_options != "" {
		d.logger.Printf("[DEBUG] driver.java: found JVM options: %s", jvm_options)
		args = append(args, jvm_options)
	}

	// Build the argument list.
	args = append(args, "-jar", filepath.Join(allocdir.TaskLocal, jarName))
	if argRaw, ok := task.Config["args"]; ok {
		args = append(args, argRaw)
	}

	// Setup the command
	// Assumes Java is in the $PATH, but could probably be detected
	cmd := executor.Command("java", args...)

	// Populate environment variables
	cmd.Command().Env = envVars.List()

	if err := cmd.Limit(task.Resources); err != nil {
		return nil, fmt.Errorf("failed to constrain resources: %s", err)
	}

	if err := cmd.ConfigureTaskDir(d.taskName, ctx.AllocDir); err != nil {
		return nil, fmt.Errorf("failed to configure task directory: %v", err)
	}

	if err := cmd.Start(); err != nil {
		return nil, fmt.Errorf("failed to start source: %v", err)
	}

	// Return a driver handle
	h := &javaHandle{
		cmd:    cmd,
		doneCh: make(chan struct{}),
		waitCh: make(chan error, 1),
	}

	go h.run()
	return h, nil
}

func (d *JavaDriver) Start(ctx *ExecContext, task *structs.Task) (DriverHandle, error) {
	var driverConfig JavaDriverConfig
	if err := mapstructure.WeakDecode(task.Config, &driverConfig); err != nil {
		return nil, err
	}
	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)
	}

	// Proceed to download an artifact to be executed.
	path, err := getter.GetArtifact(
		taskDir,
		driverConfig.ArtifactSource,
		driverConfig.Checksum,
		d.logger,
	)
	if err != nil {
		return nil, err
	}

	jarName := filepath.Base(path)

	args := []string{}
	// Look for jvm options
	if len(driverConfig.JvmOpts) != 0 {
		d.logger.Printf("[DEBUG] driver.java: found JVM options: %s", driverConfig.JvmOpts)
		args = append(args, driverConfig.JvmOpts...)
	}

	// Build the argument list.
	args = append(args, "-jar", jarName)
	if len(driverConfig.Args) != 0 {
		args = append(args, driverConfig.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,
		AllocDir:         ctx.AllocDir,
		TaskName:         task.Name,
		TaskResources:    task.Resources,
		FSIsolation:      true,
		ResourceLimits:   true,
		UnprivilegedUser: true,
	}
	ps, err := exec.LaunchCmd(&executor.ExecCommand{Cmd: "java", Args: args}, executorCtx)
	if err != nil {
		pluginClient.Kill()
		return nil, fmt.Errorf("error starting process via the plugin: %v", err)
	}
	d.logger.Printf("[DEBUG] driver.java: started process with pid: %v", ps.Pid)

	// Return a driver handle
	h := &javaHandle{
		pluginClient:    pluginClient,
		executor:        exec,
		userPid:         ps.Pid,
		isolationConfig: ps.IsolationConfig,
		taskDir:         taskDir,
		allocDir:        ctx.AllocDir,
		killTimeout:     d.DriverContext.KillTimeout(task),
		logger:          d.logger,
		doneCh:          make(chan struct{}),
		waitCh:          make(chan *cstructs.WaitResult, 1),
	}

	go h.run()
	return h, nil
}

func (d *ExecDriver) Start(ctx *ExecContext, task *structs.Task) (DriverHandle, error) {
	// Get the command to be ran
	command, ok := task.Config["command"]
	if !ok || command == "" {
		return nil, fmt.Errorf("missing command for exec driver")
	}

	// Create a location to download the artifact.
	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)
	}

	// Check if an artificat is specified and attempt to download it
	source, ok := task.Config["artifact_source"]
	if ok && source != "" {
		// Proceed to download an artifact to be executed.
		_, err := getter.GetArtifact(
			filepath.Join(taskDir, allocdir.TaskLocal),
			task.Config["artifact_source"],
			task.Config["checksum"],
			d.logger,
		)
		if err != nil {
			return nil, err
		}
	}

	// Get the environment variables.
	envVars := TaskEnvironmentVariables(ctx, task)

	// Look for arguments
	var args []string
	if argRaw, ok := task.Config["args"]; ok {
		args = append(args, argRaw)
	}

	// Setup the command
	cmd := executor.Command(command, args...)
	if err := cmd.Limit(task.Resources); err != nil {
		return nil, fmt.Errorf("failed to constrain resources: %s", err)
	}

	// Populate environment variables
	cmd.Command().Env = envVars.List()

	if err := cmd.ConfigureTaskDir(d.taskName, ctx.AllocDir); err != nil {
		return nil, fmt.Errorf("failed to configure task directory: %v", err)
	}

	if err := cmd.Start(); err != nil {
		return nil, fmt.Errorf("failed to start command: %v", err)
	}

	// Return a driver handle
	h := &execHandle{
		cmd:    cmd,
		doneCh: make(chan struct{}),
		waitCh: make(chan error, 1),
	}
	go h.run()
	return h, 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) {
	// Get the image source
	source, ok := task.Config["artifact_source"]
	if !ok || source == "" {
		return nil, fmt.Errorf("Missing source image Qemu driver")
	}

	// Qemu defaults to 128M of RAM for a given VM. Instead, we force users to
	// supply a memory size in the tasks resources
	if task.Resources == nil || task.Resources.MemoryMB == 0 {
		return nil, fmt.Errorf("Missing required Task Resource: Memory")
	}

	// 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)
	}

	// Proceed to download an artifact to be executed.
	vmPath, err := getter.GetArtifact(
		filepath.Join(taskDir, allocdir.TaskLocal),
		task.Config["artifact_source"],
		task.Config["checksum"],
		d.logger,
	)
	if err != nil {
		return nil, err
	}

	vmID := filepath.Base(vmPath)

	// Parse configuration arguments
	// Create the base arguments
	accelerator := "tcg"
	if acc, ok := task.Config["accelerator"]; ok {
		accelerator = acc
	}
	// TODO: Check a lower bounds, e.g. the default 128 of Qemu
	mem := fmt.Sprintf("%dM", task.Resources.MemoryMB)

	args := []string{
		"qemu-system-x86_64",
		"-machine", "type=pc,accel=" + accelerator,
		"-name", vmID,
		"-m", mem,
		"-drive", "file=" + vmPath,
		"-nodefconfig",
		"-nodefaults",
		"-nographic",
	}

	// 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
	if len(task.Resources.Networks) > 0 {
		// TODO: Consolidate these into map of host/guest port when we have HCL
		// Note: Host port must be open and available
		// Get and split guest ports. The guest_ports configuration must match up with
		// the Reserved ports in the Task Resources
		// Users can supply guest_hosts as a list of posts to map on the guest vm.
		// These map 1:1 with the requested Reserved Ports from the hostmachine.
		ports := strings.Split(task.Config["guest_ports"], ",")
		if len(ports) == 0 {
			return nil, fmt.Errorf("[ERR] driver.qemu: Error parsing required Guest Ports")
		}

		// TODO: support more than a single, default Network
		if len(ports) != len(task.Resources.Networks[0].ReservedPorts) {
			return nil, fmt.Errorf("[ERR] driver.qemu: Error matching Guest Ports with Reserved ports")
		}

		// Loop through the reserved ports 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
		reservedPorts := task.Resources.Networks[0].ReservedPorts
		var forwarding string
		for i, p := range ports {
			forwarding = fmt.Sprintf("%s,hostfwd=tcp::%s-:%s", forwarding, strconv.Itoa(reservedPorts[i]), p)
		}

		if "" == forwarding {
			return nil, fmt.Errorf("[ERR] driver.qemu:  Error constructing port forwarding")
		}

		args = append(args,
			"-netdev",
			fmt.Sprintf("user,id=user.0%s", forwarding),
			"-device", "virtio-net,netdev=user.0",
		)
	}

	// If using KVM, add optimization args
	if accelerator == "kvm" {
		args = append(args,
//.........這裏部分代碼省略.........