// validateJob validates a Job and task drivers and returns an error if there is
// a validation problem or if the Job is of a type a user is not allowed to
// submit.
func validateJob(job *structs.Job) error {
	validationErrors := new(multierror.Error)
	if err := job.Validate(); err != nil {
		multierror.Append(validationErrors, err)
	}

	// Validate the driver configurations.
	for _, tg := range job.TaskGroups {
		for _, task := range tg.Tasks {
			d, err := driver.NewDriver(
				task.Driver,
				driver.NewEmptyDriverContext(),
			)
			if err != nil {
				msg := "failed to create driver for task %q in group %q for validation: %v"
				multierror.Append(validationErrors, fmt.Errorf(msg, tg.Name, task.Name, err))
				continue
			}

			if err := d.Validate(task.Config); err != nil {
				formatted := fmt.Errorf("group %q -> task %q -> config: %v", tg.Name, task.Name, err)
				multierror.Append(validationErrors, formatted)
			}
		}
	}

	if job.Type == structs.JobTypeCore {
		multierror.Append(validationErrors, fmt.Errorf("job type cannot be core"))
	}

	return validationErrors.ErrorOrNil()
}

// createDriver makes a driver for the task
func (r *TaskRunner) createDriver() (driver.Driver, error) {
	driverCtx := driver.NewDriverContext(r.task.Name, r.config, r.config.Node, r.logger)
	driver, err := driver.NewDriver(r.task.Driver, driverCtx)
	if err != nil {
		err = fmt.Errorf("failed to create driver '%s' for alloc %s: %v",
			r.task.Driver, r.allocID, err)
		r.logger.Printf("[ERR] client: %s", err)
	}
	return driver, err
}

// validateJob validates a Job and task drivers and returns an error if there is
// a validation problem or if the Job is of a type a user is not allowed to
// submit.
func validateJob(job *structs.Job) error {
	validationErrors := new(multierror.Error)
	if err := job.Validate(); err != nil {
		multierror.Append(validationErrors, err)
	}

	// Get the signals required
	signals := job.RequiredSignals()

	// Validate the driver configurations.
	for _, tg := range job.TaskGroups {
		// Get the signals for the task group
		tgSignals, tgOk := signals[tg.Name]

		for _, task := range tg.Tasks {
			d, err := driver.NewDriver(
				task.Driver,
				driver.NewEmptyDriverContext(),
			)
			if err != nil {
				msg := "failed to create driver for task %q in group %q for validation: %v"
				multierror.Append(validationErrors, fmt.Errorf(msg, tg.Name, task.Name, err))
				continue
			}

			if err := d.Validate(task.Config); err != nil {
				formatted := fmt.Errorf("group %q -> task %q -> config: %v", tg.Name, task.Name, err)
				multierror.Append(validationErrors, formatted)
			}

			// The task group didn't have any task that required signals
			if !tgOk {
				continue
			}

			// This task requires signals. Ensure the driver is capable
			if required, ok := tgSignals[task.Name]; ok {
				abilities := d.Abilities()
				if !abilities.SendSignals {
					formatted := fmt.Errorf("group %q -> task %q: driver %q doesn't support sending signals. Requested signals are %v",
						tg.Name, task.Name, task.Driver, strings.Join(required, ", "))
					multierror.Append(validationErrors, formatted)
				}
			}
		}
	}

	if job.Type == structs.JobTypeCore {
		multierror.Append(validationErrors, fmt.Errorf("job type cannot be core"))
	}

	return validationErrors.ErrorOrNil()
}

// createDriver makes a driver for the task
func (r *TaskRunner) createDriver() (driver.Driver, error) {
	if r.taskEnv == nil {
		return nil, fmt.Errorf("task environment not made for task %q in allocation %q", r.task.Name, r.alloc.ID)
	}

	driverCtx := driver.NewDriverContext(r.task.Name, r.config, r.config.Node, r.logger, r.taskEnv)
	driver, err := driver.NewDriver(r.task.Driver, driverCtx)
	if err != nil {
		return nil, fmt.Errorf("failed to create driver '%s' for alloc %s: %v",
			r.task.Driver, r.alloc.ID, err)
	}
	return driver, err
}

// setupDrivers is used to find the available drivers
func (c *Client) setupDrivers() error {
	// Build the whitelist of drivers.
	whitelist := c.config.ReadStringListToMap("driver.whitelist")
	whitelistEnabled := len(whitelist) > 0

	var avail []string
	var skipped []string
	driverCtx := driver.NewDriverContext("", c.config, c.config.Node, c.logger, nil)
	for name := range driver.BuiltinDrivers {
		// Skip fingerprinting drivers that are not in the whitelist if it is
		// enabled.
		if _, ok := whitelist[name]; whitelistEnabled && !ok {
			skipped = append(skipped, name)
			continue
		}

		d, err := driver.NewDriver(name, driverCtx)
		if err != nil {
			return err
		}
		c.configLock.Lock()
		applies, err := d.Fingerprint(c.config, c.config.Node)
		c.configLock.Unlock()
		if err != nil {
			return err
		}
		if applies {
			avail = append(avail, name)
		}

		p, period := d.Periodic()
		if p {
			go c.fingerprintPeriodic(name, d, period)
		}

	}

	c.logger.Printf("[DEBUG] client: available drivers %v", avail)

	if len(skipped) != 0 {
		c.logger.Printf("[DEBUG] client: drivers skipped due to whitelist: %v", skipped)
	}

	return nil
}

// setupDrivers is used to find the available drivers
func (c *Client) setupDrivers() error {
	// Build the whitelist of drivers.
	userWhitelist := strings.TrimSpace(c.config.ReadDefault("driver.whitelist", ""))
	whitelist := make(map[string]struct{})
	if userWhitelist != "" {
		for _, driver := range strings.Split(userWhitelist, ",") {
			trimmed := strings.TrimSpace(driver)
			whitelist[trimmed] = struct{}{}
		}
	}
	whitelistEnabled := len(whitelist) > 0

	var avail []string
	var skipped []string
	driverCtx := driver.NewDriverContext("", c.config, c.config.Node, c.logger)
	for name := range driver.BuiltinDrivers {
		// Skip fingerprinting drivers that are not in the whitelist if it is
		// enabled.
		if _, ok := whitelist[name]; whitelistEnabled && !ok {
			skipped = append(skipped, name)
			continue
		}

		d, err := driver.NewDriver(name, driverCtx)
		if err != nil {
			return err
		}
		applies, err := d.Fingerprint(c.config, c.config.Node)
		if err != nil {
			return err
		}
		if applies {
			avail = append(avail, name)
		}
	}

	c.logger.Printf("[DEBUG] client: available drivers %v", avail)

	if len(skipped) != 0 {
		c.logger.Printf("[DEBUG] client: drivers skipped due to whitelist: %v", skipped)
	}

	return nil
}

// setupDrivers is used to find the available drivers
func (c *Client) setupDrivers() error {
	var avail []string
	driverCtx := driver.NewDriverContext("", c.config, c.config.Node, c.logger)
	for name := range driver.BuiltinDrivers {
		d, err := driver.NewDriver(name, driverCtx)
		if err != nil {
			return err
		}
		applies, err := d.Fingerprint(c.config, c.config.Node)
		if err != nil {
			return err
		}
		if applies {
			avail = append(avail, name)
		}
	}
	c.logger.Printf("[DEBUG] client: available drivers %v", avail)
	return nil
}

//.........这里部分代码省略.........
		// If we have env, then parse them
		if o := listVal.Filter("env"); len(o.Items) > 0 {
			for _, o := range o.Elem().Items {
				var m map[string]interface{}
				if err := hcl.DecodeObject(&m, o.Val); err != nil {
					return err
				}
				if err := mapstructure.WeakDecode(m, &t.Env); err != nil {
					return err
				}
			}
		}

		if o := listVal.Filter("service"); len(o.Items) > 0 {
			if err := parseServices(jobName, taskGroupName, &t, o); err != nil {
				return multierror.Prefix(err, fmt.Sprintf("'%s',", n))
			}
		}

		// If we have config, then parse that
		if o := listVal.Filter("config"); len(o.Items) > 0 {
			for _, o := range o.Elem().Items {
				var m map[string]interface{}
				if err := hcl.DecodeObject(&m, o.Val); err != nil {
					return err
				}

				if err := mapstructure.WeakDecode(m, &t.Config); err != nil {
					return err
				}
			}

			// Instantiate a driver to validate the configuration
			d, err := driver.NewDriver(
				t.Driver,
				driver.NewEmptyDriverContext(),
			)

			if err != nil {
				return multierror.Prefix(err,
					fmt.Sprintf("'%s', config ->", n))
			}

			if err := d.Validate(t.Config); err != nil {
				return multierror.Prefix(err,
					fmt.Sprintf("'%s', config ->", n))
			}
		}

		// Parse constraints
		if o := listVal.Filter("constraint"); len(o.Items) > 0 {
			if err := parseConstraints(&t.Constraints, o); err != nil {
				return multierror.Prefix(err, fmt.Sprintf(
					"'%s', constraint ->", n))
			}
		}

		// Parse out meta fields. These are in HCL as a list so we need
		// to iterate over them and merge them.
		if metaO := listVal.Filter("meta"); len(metaO.Items) > 0 {
			for _, o := range metaO.Elem().Items {
				var m map[string]interface{}
				if err := hcl.DecodeObject(&m, o.Val); err != nil {
					return err
				}
				if err := mapstructure.WeakDecode(m, &t.Meta); err != nil {

// Register is used to upsert a job for scheduling
func (j *Job) Register(args *structs.JobRegisterRequest, reply *structs.JobRegisterResponse) error {
	if done, err := j.srv.forward("Job.Register", args, args, reply); done {
		return err
	}
	defer metrics.MeasureSince([]string{"nomad", "job", "register"}, time.Now())

	// Validate the arguments
	if args.Job == nil {
		return fmt.Errorf("missing job for registration")
	}

	// Initialize the job fields (sets defaults and any necessary init work).
	args.Job.InitFields()

	if err := args.Job.Validate(); err != nil {
		return err
	}

	// Validate the driver configurations.
	var driverErrors multierror.Error
	for _, tg := range args.Job.TaskGroups {
		for _, task := range tg.Tasks {
			d, err := driver.NewDriver(
				task.Driver,
				driver.NewEmptyDriverContext(),
			)
			if err != nil {
				msg := "failed to create driver for task %q in group %q for validation: %v"
				driverErrors.Errors = append(driverErrors.Errors, fmt.Errorf(msg, tg.Name, task.Name, err))
				continue
			}

			if err := d.Validate(task.Config); err != nil {
				formatted := fmt.Errorf("group %q -> task %q -> config: %v", tg.Name, task.Name, err)
				driverErrors.Errors = append(driverErrors.Errors, formatted)
			}
		}
	}

	if len(driverErrors.Errors) != 0 {
		return driverErrors.ErrorOrNil()
	}

	if args.Job.Type == structs.JobTypeCore {
		return fmt.Errorf("job type cannot be core")
	}

	// Commit this update via Raft
	_, index, err := j.srv.raftApply(structs.JobRegisterRequestType, args)
	if err != nil {
		j.srv.logger.Printf("[ERR] nomad.job: Register failed: %v", err)
		return err
	}

	// Populate the reply with job information
	reply.JobModifyIndex = index

	// If the job is periodic, we don't create an eval.
	if args.Job.IsPeriodic() {
		return nil
	}

	// Create a new evaluation
	eval := &structs.Evaluation{
		ID:             structs.GenerateUUID(),
		Priority:       args.Job.Priority,
		Type:           args.Job.Type,
		TriggeredBy:    structs.EvalTriggerJobRegister,
		JobID:          args.Job.ID,
		JobModifyIndex: index,
		Status:         structs.EvalStatusPending,
	}
	update := &structs.EvalUpdateRequest{
		Evals:        []*structs.Evaluation{eval},
		WriteRequest: structs.WriteRequest{Region: args.Region},
	}

	// Commit this evaluation via Raft
	// XXX: There is a risk of partial failure where the JobRegister succeeds
	// but that the EvalUpdate does not.
	_, evalIndex, err := j.srv.raftApply(structs.EvalUpdateRequestType, update)
	if err != nil {
		j.srv.logger.Printf("[ERR] nomad.job: Eval create failed: %v", err)
		return err
	}

	// Populate the reply with eval information
	reply.EvalID = eval.ID
	reply.EvalCreateIndex = evalIndex
	reply.Index = evalIndex
	return nil
}