Golang ResourceVariable.ResourceId方法代碼示例

func (c *Context) computeResourceVariable(
	v *config.ResourceVariable) (string, error) {
	id := v.ResourceId()
	if v.Multi {
		id = fmt.Sprintf("%s.%d", id, v.Index)
	}

	c.sl.RLock()
	defer c.sl.RUnlock()

	r, ok := c.state.Resources[id]
	if !ok {
		return "", fmt.Errorf(
			"Resource '%s' not found for variable '%s'",
			id,
			v.FullKey())
	}

	attr, ok := r.Attributes[v.Field]
	if !ok {
		return "", fmt.Errorf(
			"Resource '%s' does not have attribute '%s' "+
				"for variable '%s'",
			id,
			v.Field,
			v.FullKey())
	}

	return attr, nil
}

func (c *walkContext) resourceVariableInfo(
	v *config.ResourceVariable) (*ModuleState, *config.Resource, error) {
	// Get the module tree that contains our current path. This is
	// either the current module (path is empty) or a child.
	var modTree *module.Tree
	childPath := c.Path[1:len(c.Path)]
	if len(childPath) == 0 {
		modTree = c.Context.module
	} else {
		modTree = c.Context.module.Child(childPath)
	}

	// Get the resource from the configuration so we can verify
	// that the resource is in the configuration and so we can access
	// the configuration if we need to.
	var cr *config.Resource
	for _, r := range modTree.Config().Resources {
		if r.Id() == v.ResourceId() {
			cr = r
			break
		}
	}
	if cr == nil {
		return nil, nil, fmt.Errorf(
			"Resource '%s' not found for variable '%s'",
			v.ResourceId(),
			v.FullKey())
	}

	// Get the relevant module
	module := c.Context.state.ModuleByPath(c.Path)
	return module, cr, nil
}

func (i *Interpolater) resourceVariableInfo(
	scope *InterpolationScope,
	v *config.ResourceVariable) (*ModuleState, *config.Resource, error) {
	// Get the module tree that contains our current path. This is
	// either the current module (path is empty) or a child.
	modTree := i.Module
	if len(scope.Path) > 1 {
		modTree = i.Module.Child(scope.Path[1:])
	}

	// Get the resource from the configuration so we can verify
	// that the resource is in the configuration and so we can access
	// the configuration if we need to.
	var cr *config.Resource
	for _, r := range modTree.Config().Resources {
		if r.Id() == v.ResourceId() {
			cr = r
			break
		}
	}
	if cr == nil {
		return nil, nil, fmt.Errorf(
			"Resource '%s' not found for variable '%s'",
			v.ResourceId(),
			v.FullKey())
	}

	// Get the relevant module
	module := i.State.ModuleByPath(scope.Path)
	return module, cr, nil
}

func (c *Context) computeResourceMultiVariable(
	v *config.ResourceVariable) (string, error) {
	c.sl.RLock()
	defer c.sl.RUnlock()

	// Get the resource from the configuration so we can know how
	// many of the resource there is.
	var cr *config.Resource
	for _, r := range c.config.Resources {
		if r.Id() == v.ResourceId() {
			cr = r
			break
		}
	}
	if cr == nil {
		return "", fmt.Errorf(
			"Resource '%s' not found for variable '%s'",
			v.ResourceId(),
			v.FullKey())
	}

	var values []string
	for i := 0; i < cr.Count; i++ {
		id := fmt.Sprintf("%s.%d", v.ResourceId(), i)

		// If we're dealing with only a single resource, then the
		// ID doesn't have a trailing index.
		if cr.Count == 1 {
			id = v.ResourceId()
		}

		r, ok := c.state.Resources[id]
		if !ok {
			continue
		}

		attr, ok := r.Attributes[v.Field]
		if !ok {
			continue
		}

		values = append(values, attr)
	}

	if len(values) == 0 {
		return "", fmt.Errorf(
			"Resource '%s' does not have attribute '%s' "+
				"for variable '%s'",
			v.ResourceId(),
			v.Field,
			v.FullKey())
	}

	return strings.Join(values, ","), nil
}

func (c *Context) computeResourceVariable(
	v *config.ResourceVariable) (string, error) {
	id := v.ResourceId()
	if v.Multi {
		id = fmt.Sprintf("%s.%d", id, v.Index)
	}

	c.sl.RLock()
	defer c.sl.RUnlock()

	r, ok := c.state.Resources[id]
	if !ok {
		return "", fmt.Errorf(
			"Resource '%s' not found for variable '%s'",
			id,
			v.FullKey())
	}

	attr, ok := r.Attributes[v.Field]
	if ok {
		return attr, nil
	}

	// We didn't find the exact field, so lets separate the dots
	// and see if anything along the way is a computed set. i.e. if
	// we have "foo.0.bar" as the field, check to see if "foo" is
	// a computed list. If so, then the whole thing is computed.
	parts := strings.Split(v.Field, ".")
	if len(parts) > 1 {
		for i := 1; i < len(parts); i++ {
			key := fmt.Sprintf("%s.#", strings.Join(parts[:i], "."))
			if attr, ok := r.Attributes[key]; ok {
				return attr, nil
			}
		}
	}

	return "", fmt.Errorf(
		"Resource '%s' does not have attribute '%s' "+
			"for variable '%s'",
		id,
		v.Field,
		v.FullKey())
}

func (i *Interpolater) resourceCountKeys(
	ms *ModuleState,
	cr *config.Resource,
	v *config.ResourceVariable) ([]string, error) {
	id := v.ResourceId()

	// If we're NOT applying, then we assume we can read the count
	// from the state. Plan and so on may not have any state yet so
	// we do a full interpolation.
	if i.Operation != walkApply {
		count, err := cr.Count()
		if err != nil {
			return nil, err
		}

		result := make([]string, count)
		for i := 0; i < count; i++ {
			result[i] = fmt.Sprintf("%s.%d", id, i)
		}

		return result, nil
	}

	// We need to determine the list of resource keys to get values from.
	// This needs to be sorted so the order is deterministic. We used to
	// use "cr.Count()" but that doesn't work if the count is interpolated
	// and we can't guarantee that so we instead depend on the state.
	var resourceKeys []string
	for k, _ := range ms.Resources {
		// If we don't have the right prefix then ignore it
		if k != id && !strings.HasPrefix(k, id+".") {
			continue
		}

		// Add it to the list
		resourceKeys = append(resourceKeys, k)
	}
	sort.Strings(resourceKeys)
	return resourceKeys, nil
}

func (i *Interpolater) computeResourceVariable(
	scope *InterpolationScope,
	v *config.ResourceVariable) (string, error) {
	id := v.ResourceId()
	if v.Multi {
		id = fmt.Sprintf("%s.%d", id, v.Index)
	}

	i.StateLock.RLock()
	defer i.StateLock.RUnlock()

	// Get the information about this resource variable, and verify
	// that it exists and such.
	module, _, err := i.resourceVariableInfo(scope, v)
	if err != nil {
		return "", err
	}

	// If we have no module in the state yet or count, return empty
	if module == nil || len(module.Resources) == 0 {
		return "", nil
	}

	// Get the resource out from the state. We know the state exists
	// at this point and if there is a state, we expect there to be a
	// resource with the given name.
	r, ok := module.Resources[id]
	if !ok && v.Multi && v.Index == 0 {
		r, ok = module.Resources[v.ResourceId()]
	}
	if !ok {
		r = nil
	}
	if r == nil {
		goto MISSING
	}

	if r.Primary == nil {
		goto MISSING
	}

	if attr, ok := r.Primary.Attributes[v.Field]; ok {
		return attr, nil
	}

	// At apply time, we can't do the "maybe has it" check below
	// that we need for plans since parent elements might be computed.
	// Therefore, it is an error and we're missing the key.
	//
	// TODO: test by creating a state and configuration that is referencing
	// a non-existent variable "foo.bar" where the state only has "foo"
	// and verify plan works, but apply doesn't.
	if i.Operation == walkApply {
		goto MISSING
	}

	// We didn't find the exact field, so lets separate the dots
	// and see if anything along the way is a computed set. i.e. if
	// we have "foo.0.bar" as the field, check to see if "foo" is
	// a computed list. If so, then the whole thing is computed.
	if parts := strings.Split(v.Field, "."); len(parts) > 1 {
		for i := 1; i < len(parts); i++ {
			// Lists and sets make this
			key := fmt.Sprintf("%s.#", strings.Join(parts[:i], "."))
			if attr, ok := r.Primary.Attributes[key]; ok {
				return attr, nil
			}

			// Maps make this
			key = fmt.Sprintf("%s", strings.Join(parts[:i], "."))
			if attr, ok := r.Primary.Attributes[key]; ok {
				return attr, nil
			}
		}
	}

MISSING:
	// Validation for missing interpolations should happen at a higher
	// semantic level. If we reached this point and don't have variables,
	// just return the computed value.
	if scope == nil && scope.Resource == nil {
		return config.UnknownVariableValue, nil
	}

	// If the operation is refresh, it isn't an error for a value to
	// be unknown. Instead, we return that the value is computed so
	// that the graph can continue to refresh other nodes. It doesn't
	// matter because the config isn't interpolated anyways.
	if i.Operation == walkRefresh {
		return config.UnknownVariableValue, nil
	}

	return "", fmt.Errorf(
		"Resource '%s' does not have attribute '%s' "+
			"for variable '%s'",
		id,
		v.Field,
		v.FullKey())
}

func (i *Interpolater) computeResourceMultiVariable(
	scope *InterpolationScope,
	v *config.ResourceVariable) (string, error) {
	i.StateLock.RLock()
	defer i.StateLock.RUnlock()

	// Get the information about this resource variable, and verify
	// that it exists and such.
	module, cr, err := i.resourceVariableInfo(scope, v)
	if err != nil {
		return "", err
	}

	// Get the count so we know how many to iterate over
	count, err := cr.Count()
	if err != nil {
		return "", fmt.Errorf(
			"Error reading %s count: %s",
			v.ResourceId(),
			err)
	}

	// If we have no module in the state yet or count, return empty
	if module == nil || len(module.Resources) == 0 || count == 0 {
		return "", nil
	}

	var values []string
	for j := 0; j < count; j++ {
		id := fmt.Sprintf("%s.%d", v.ResourceId(), j)

		// If we're dealing with only a single resource, then the
		// ID doesn't have a trailing index.
		if count == 1 {
			id = v.ResourceId()
		}

		r, ok := module.Resources[id]
		if !ok {
			continue
		}

		if r.Primary == nil {
			continue
		}

		attr, ok := r.Primary.Attributes[v.Field]
		if !ok {
			// computed list attribute
			_, ok := r.Primary.Attributes[v.Field+".#"]
			if !ok {
				continue
			}
			attr, err = i.interpolateListAttribute(v.Field, r.Primary.Attributes)
			if err != nil {
				return "", err
			}
		}

		if config.IsStringList(attr) {
			for _, s := range config.StringList(attr).Slice() {
				values = append(values, s)
			}
			continue
		}

		// If any value is unknown, the whole thing is unknown
		if attr == config.UnknownVariableValue {
			return config.UnknownVariableValue, nil
		}

		values = append(values, attr)
	}

	if len(values) == 0 {
		// If the operation is refresh, it isn't an error for a value to
		// be unknown. Instead, we return that the value is computed so
		// that the graph can continue to refresh other nodes. It doesn't
		// matter because the config isn't interpolated anyways.
		//
		// For a Destroy, we're also fine with computed values, since our goal is
		// only to get destroy nodes for existing resources.
		//
		// For an input walk, computed values are okay to return because we're only
		// looking for missing variables to prompt the user for.
		if i.Operation == walkRefresh || i.Operation == walkPlanDestroy || i.Operation == walkDestroy || i.Operation == walkInput {
			return config.UnknownVariableValue, nil
		}

		return "", fmt.Errorf(
			"Resource '%s' does not have attribute '%s' "+
				"for variable '%s'",
			v.ResourceId(),
			v.Field,
			v.FullKey())
	}

	return config.NewStringList(values).String(), nil
}

func (i *Interpolater) resourceCountMax(
	ms *ModuleState,
	cr *config.Resource,
	v *config.ResourceVariable) (int, error) {
	id := v.ResourceId()

	// If we're NOT applying, then we assume we can read the count
	// from the state. Plan and so on may not have any state yet so
	// we do a full interpolation.
	if i.Operation != walkApply {
		count, err := cr.Count()
		if err != nil {
			return 0, err
		}

		return count, nil
	}

	// We need to determine the list of resource keys to get values from.
	// This needs to be sorted so the order is deterministic. We used to
	// use "cr.Count()" but that doesn't work if the count is interpolated
	// and we can't guarantee that so we instead depend on the state.
	max := -1
	for k, _ := range ms.Resources {
		// Get the index number for this resource
		index := ""
		if k == id {
			// If the key is the id, then its just 0 (no explicit index)
			index = "0"
		} else if strings.HasPrefix(k, id+".") {
			// Grab the index number out of the state
			index = k[len(id+"."):]
			if idx := strings.IndexRune(index, '.'); idx >= 0 {
				index = index[:idx]
			}
		}

		// If there was no index then this resource didn't match
		// the one we're looking for, exit.
		if index == "" {
			continue
		}

		// Turn the index into an int
		raw, err := strconv.ParseInt(index, 0, 0)
		if err != nil {
			return 0, fmt.Errorf(
				"%s: error parsing index %q as int: %s",
				id, index, err)
		}

		// Keep track of this index if its the max
		if new := int(raw); new > max {
			max = new
		}
	}

	// If we never found any matching resources in the state, we
	// have zero.
	if max == -1 {
		return 0, nil
	}

	// The result value is "max+1" because we're returning the
	// max COUNT, not the max INDEX, and we zero-index.
	return max + 1, nil
}

func (i *Interpolater) computeResourceMultiVariable(
	scope *InterpolationScope,
	v *config.ResourceVariable) (*ast.Variable, error) {
	i.StateLock.RLock()
	defer i.StateLock.RUnlock()

	unknownVariable := unknownVariable()

	// Get the information about this resource variable, and verify
	// that it exists and such.
	module, cr, err := i.resourceVariableInfo(scope, v)
	if err != nil {
		return nil, err
	}

	// Get the keys for all the resources that are created for this resource
	countMax, err := i.resourceCountMax(module, cr, v)
	if err != nil {
		return nil, err
	}

	// If count is zero, we return an empty list
	if countMax == 0 {
		return &ast.Variable{Type: ast.TypeList, Value: []ast.Variable{}}, nil
	}

	// If we have no module in the state yet or count, return unknown
	if module == nil || len(module.Resources) == 0 {
		return &unknownVariable, nil
	}

	var values []interface{}
	for idx := 0; idx < countMax; idx++ {
		id := fmt.Sprintf("%s.%d", v.ResourceId(), idx)

		// ID doesn't have a trailing index. We try both here, but if a value
		// without a trailing index is found we prefer that. This choice
		// is for legacy reasons: older versions of TF preferred it.
		if id == v.ResourceId()+".0" {
			potential := v.ResourceId()
			if _, ok := module.Resources[potential]; ok {
				id = potential
			}
		}

		r, ok := module.Resources[id]
		if !ok {
			continue
		}

		if r.Primary == nil {
			continue
		}

		if singleAttr, ok := r.Primary.Attributes[v.Field]; ok {
			if singleAttr == config.UnknownVariableValue {
				return &unknownVariable, nil
			}

			values = append(values, singleAttr)
			continue
		}

		// computed list or map attribute
		_, isList := r.Primary.Attributes[v.Field+".#"]
		_, isMap := r.Primary.Attributes[v.Field+".%"]
		if !(isList || isMap) {
			continue
		}
		multiAttr, err := i.interpolateComplexTypeAttribute(v.Field, r.Primary.Attributes)
		if err != nil {
			return nil, err
		}

		if multiAttr == unknownVariable {
			return &unknownVariable, nil
		}

		values = append(values, multiAttr)
	}

	if len(values) == 0 {
		// If the operation is refresh, it isn't an error for a value to
		// be unknown. Instead, we return that the value is computed so
		// that the graph can continue to refresh other nodes. It doesn't
		// matter because the config isn't interpolated anyways.
		//
		// For a Destroy, we're also fine with computed values, since our goal is
		// only to get destroy nodes for existing resources.
		//
		// For an input walk, computed values are okay to return because we're only
		// looking for missing variables to prompt the user for.
		if i.Operation == walkRefresh || i.Operation == walkPlanDestroy || i.Operation == walkDestroy || i.Operation == walkInput {
			return &unknownVariable, nil
		}

		return nil, fmt.Errorf(
			"Resource '%s' does not have attribute '%s' "+
				"for variable '%s'",
			v.ResourceId(),
//.........這裏部分代碼省略.........

func (c *walkContext) computeResourceMultiVariable(
	v *config.ResourceVariable) (string, error) {
	c.Context.sl.RLock()
	defer c.Context.sl.RUnlock()

	// Get the information about this resource variable, and verify
	// that it exists and such.
	module, cr, err := c.resourceVariableInfo(v)
	if err != nil {
		return "", err
	}

	// Get the count so we know how many to iterate over
	count, err := cr.Count()
	if err != nil {
		return "", fmt.Errorf(
			"Error reading %s count: %s",
			v.ResourceId(),
			err)
	}

	// If we have no module in the state yet or count, return empty
	if module == nil || len(module.Resources) == 0 || count == 0 {
		return "", nil
	}

	var values []string
	for i := 0; i < count; i++ {
		id := fmt.Sprintf("%s.%d", v.ResourceId(), i)

		// If we're dealing with only a single resource, then the
		// ID doesn't have a trailing index.
		if count == 1 {
			id = v.ResourceId()
		}

		r, ok := module.Resources[id]
		if !ok {
			continue
		}

		if r.Primary == nil {
			continue
		}

		attr, ok := r.Primary.Attributes[v.Field]
		if !ok {
			continue
		}

		values = append(values, attr)
	}

	if len(values) == 0 {
		return "", fmt.Errorf(
			"Resource '%s' does not have attribute '%s' "+
				"for variable '%s'",
			v.ResourceId(),
			v.Field,
			v.FullKey())
	}

	return strings.Join(values, config.InterpSplitDelim), nil
}

func (i *Interpolater) computeResourceMultiVariable(
	scope *InterpolationScope,
	v *config.ResourceVariable) (*ast.Variable, error) {
	i.StateLock.RLock()
	defer i.StateLock.RUnlock()

	unknownVariable := unknownVariable()

	// Get the information about this resource variable, and verify
	// that it exists and such.
	module, cr, err := i.resourceVariableInfo(scope, v)
	if err != nil {
		return nil, err
	}

	// Get the count so we know how many to iterate over
	count, err := cr.Count()
	if err != nil {
		return nil, fmt.Errorf(
			"Error reading %s count: %s",
			v.ResourceId(),
			err)
	}

	// If count is zero, we return an empty list
	if count == 0 {
		return &ast.Variable{Type: ast.TypeList, Value: []ast.Variable{}}, nil
	}

	// If we have no module in the state yet or count, return unknown
	if module == nil || len(module.Resources) == 0 {
		return &unknownVariable, nil
	}

	var values []interface{}
	for j := 0; j < count; j++ {
		id := fmt.Sprintf("%s.%d", v.ResourceId(), j)

		// If we're dealing with only a single resource, then the
		// ID doesn't have a trailing index.
		if count == 1 {
			id = v.ResourceId()
		}

		r, ok := module.Resources[id]
		if !ok {
			continue
		}

		if r.Primary == nil {
			continue
		}

		if singleAttr, ok := r.Primary.Attributes[v.Field]; ok {
			if singleAttr == config.UnknownVariableValue {
				return &unknownVariable, nil
			}

			values = append(values, singleAttr)
			continue
		}

		// computed list or map attribute
		_, isList := r.Primary.Attributes[v.Field+".#"]
		_, isMap := r.Primary.Attributes[v.Field+".%"]
		if !(isList || isMap) {
			continue
		}
		multiAttr, err := i.interpolateComplexTypeAttribute(v.Field, r.Primary.Attributes)
		if err != nil {
			return nil, err
		}

		if multiAttr == unknownVariable {
			return &ast.Variable{Type: ast.TypeString, Value: ""}, nil
		}

		values = append(values, multiAttr)
	}

	if len(values) == 0 {
		// If the operation is refresh, it isn't an error for a value to
		// be unknown. Instead, we return that the value is computed so
		// that the graph can continue to refresh other nodes. It doesn't
		// matter because the config isn't interpolated anyways.
		//
		// For a Destroy, we're also fine with computed values, since our goal is
		// only to get destroy nodes for existing resources.
		//
		// For an input walk, computed values are okay to return because we're only
		// looking for missing variables to prompt the user for.
		if i.Operation == walkRefresh || i.Operation == walkPlanDestroy || i.Operation == walkDestroy || i.Operation == walkInput {
			return &unknownVariable, nil
		}

		return nil, fmt.Errorf(
			"Resource '%s' does not have attribute '%s' "+
				"for variable '%s'",
			v.ResourceId(),
			v.Field,
//.........這裏部分代碼省略.........

func (i *Interpolater) computeResourceMultiVariable(
	scope *InterpolationScope,
	v *config.ResourceVariable) (string, error) {
	i.StateLock.RLock()
	defer i.StateLock.RUnlock()

	// Get the information about this resource variable, and verify
	// that it exists and such.
	module, cr, err := i.resourceVariableInfo(scope, v)
	if err != nil {
		return "", err
	}

	// Get the count so we know how many to iterate over
	count, err := cr.Count()
	if err != nil {
		return "", fmt.Errorf(
			"Error reading %s count: %s",
			v.ResourceId(),
			err)
	}

	// If we have no module in the state yet or count, return empty
	if module == nil || len(module.Resources) == 0 || count == 0 {
		return "", nil
	}

	var values []string
	for i := 0; i < count; i++ {
		id := fmt.Sprintf("%s.%d", v.ResourceId(), i)

		// If we're dealing with only a single resource, then the
		// ID doesn't have a trailing index.
		if count == 1 {
			id = v.ResourceId()
		}

		r, ok := module.Resources[id]
		if !ok {
			continue
		}

		if r.Primary == nil {
			continue
		}

		attr, ok := r.Primary.Attributes[v.Field]
		if !ok {
			continue
		}

		values = append(values, attr)
	}

	if len(values) == 0 {
		// If the operation is refresh, it isn't an error for a value to
		// be unknown. Instead, we return that the value is computed so
		// that the graph can continue to refresh other nodes. It doesn't
		// matter because the config isn't interpolated anyways.
		if i.Operation == walkRefresh {
			return config.UnknownVariableValue, nil
		}

		return "", fmt.Errorf(
			"Resource '%s' does not have attribute '%s' "+
				"for variable '%s'",
			v.ResourceId(),
			v.Field,
			v.FullKey())
	}

	return strings.Join(values, config.InterpSplitDelim), nil
}

func (i *Interpolater) computeResourceVariable(
	scope *InterpolationScope,
	v *config.ResourceVariable) (*ast.Variable, error) {
	id := v.ResourceId()
	if v.Multi {
		id = fmt.Sprintf("%s.%d", id, v.Index)
	}

	i.StateLock.RLock()
	defer i.StateLock.RUnlock()

	unknownVariable := unknownVariable()

	// These variables must be declared early because of the use of GOTO
	var isList bool
	var isMap bool

	// Get the information about this resource variable, and verify
	// that it exists and such.
	module, cr, err := i.resourceVariableInfo(scope, v)
	if err != nil {
		return nil, err
	}

	// If we're requesting "count" its a special variable that we grab
	// directly from the config itself.
	if v.Field == "count" {
		var count int
		if cr != nil {
			count, err = cr.Count()
		} else {
			count, err = i.resourceCountMax(module, cr, v)
		}
		if err != nil {
			return nil, fmt.Errorf(
				"Error reading %s count: %s",
				v.ResourceId(),
				err)
		}

		return &ast.Variable{Type: ast.TypeInt, Value: count}, nil
	}

	// Get the resource out from the state. We know the state exists
	// at this point and if there is a state, we expect there to be a
	// resource with the given name.
	var r *ResourceState
	if module != nil && len(module.Resources) > 0 {
		var ok bool
		r, ok = module.Resources[id]
		if !ok && v.Multi && v.Index == 0 {
			r, ok = module.Resources[v.ResourceId()]
		}
		if !ok {
			r = nil
		}
	}
	if r == nil || r.Primary == nil {
		if i.Operation == walkApply || i.Operation == walkPlan {
			return nil, fmt.Errorf(
				"Resource '%s' not found for variable '%s'",
				v.ResourceId(),
				v.FullKey())
		}

		// If we have no module in the state yet or count, return empty.
		// NOTE(@mitchellh): I actually don't know why this is here. During
		// a refactor I kept this here to maintain the same behavior, but
		// I'm not sure why its here.
		if module == nil || len(module.Resources) == 0 {
			return nil, nil
		}

		goto MISSING
	}

	if attr, ok := r.Primary.Attributes[v.Field]; ok {
		v, err := hil.InterfaceToVariable(attr)
		return &v, err
	}

	// computed list or map attribute
	_, isList = r.Primary.Attributes[v.Field+".#"]
	_, isMap = r.Primary.Attributes[v.Field+".%"]
	if isList || isMap {
		variable, err := i.interpolateComplexTypeAttribute(v.Field, r.Primary.Attributes)
		return &variable, err
	}

	// At apply time, we can't do the "maybe has it" check below
	// that we need for plans since parent elements might be computed.
	// Therefore, it is an error and we're missing the key.
	//
	// TODO: test by creating a state and configuration that is referencing
	// a non-existent variable "foo.bar" where the state only has "foo"
	// and verify plan works, but apply doesn't.
	if i.Operation == walkApply || i.Operation == walkDestroy {
		goto MISSING
	}

//.........這裏部分代碼省略.........

func (c *walkContext) computeResourceVariable(
	v *config.ResourceVariable) (string, error) {
	id := v.ResourceId()
	if v.Multi {
		id = fmt.Sprintf("%s.%d", id, v.Index)
	}

	c.Context.sl.RLock()
	defer c.Context.sl.RUnlock()

	// Get the information about this resource variable, and verify
	// that it exists and such.
	module, _, err := c.resourceVariableInfo(v)
	if err != nil {
		return "", err
	}

	// If we have no module in the state yet or count, return empty
	if module == nil || len(module.Resources) == 0 {
		return "", nil
	}

	// Get the resource out from the state. We know the state exists
	// at this point and if there is a state, we expect there to be a
	// resource with the given name.
	r, ok := module.Resources[id]
	if !ok && v.Multi && v.Index == 0 {
		r, ok = module.Resources[v.ResourceId()]
	}
	if !ok {
		r = nil
	}
	if r == nil {
		return "", fmt.Errorf(
			"Resource '%s' not found for variable '%s'",
			id,
			v.FullKey())
	}

	if r.Primary == nil {
		goto MISSING
	}

	if attr, ok := r.Primary.Attributes[v.Field]; ok {
		return attr, nil
	}

	// At apply time, we can't do the "maybe has it" check below
	// that we need for plans since parent elements might be computed.
	// Therefore, it is an error and we're missing the key.
	//
	// TODO: test by creating a state and configuration that is referencing
	// a non-existent variable "foo.bar" where the state only has "foo"
	// and verify plan works, but apply doesn't.
	if c.Operation == walkApply {
		goto MISSING
	}

	// We didn't find the exact field, so lets separate the dots
	// and see if anything along the way is a computed set. i.e. if
	// we have "foo.0.bar" as the field, check to see if "foo" is
	// a computed list. If so, then the whole thing is computed.
	if parts := strings.Split(v.Field, "."); len(parts) > 1 {
		for i := 1; i < len(parts); i++ {
			// Lists and sets make this
			key := fmt.Sprintf("%s.#", strings.Join(parts[:i], "."))
			if attr, ok := r.Primary.Attributes[key]; ok {
				return attr, nil
			}

			// Maps make this
			key = fmt.Sprintf("%s", strings.Join(parts[:i], "."))
			if attr, ok := r.Primary.Attributes[key]; ok {
				return attr, nil
			}
		}
	}

MISSING:
	return "", fmt.Errorf(
		"Resource '%s' does not have attribute '%s' "+
			"for variable '%s'",
		id,
		v.Field,
		v.FullKey())
}