package config
import (
"fmt"
"strconv"
"strings"
"github.com/hashicorp/hil/ast"
)
// An InterpolatedVariable is a variable reference within an interpolation.
//
// Implementations of this interface represents various sources where
// variables can come from: user variables, resources, etc.
type InterpolatedVariable interface {
FullKey() string
}
// CountVariable is a variable for referencing information about
// the count.
type CountVariable struct {
Type CountValueType
key string
}
// CountValueType is the type of the count variable that is referenced.
type CountValueType byte
const (
CountValueInvalid CountValueType = iota
CountValueIndex
)
// A ModuleVariable is a variable that is referencing the output
// of a module, such as "${module.foo.bar}"
type ModuleVariable struct {
Name string
Field string
key string
}
// A PathVariable is a variable that references path information about the
// module.
type PathVariable struct {
Type PathValueType
key string
}
type PathValueType byte
const (
PathValueInvalid PathValueType = iota
PathValueCwd
PathValueModule
PathValueRoot
)
// A ResourceVariable is a variable that is referencing the field
// of a resource, such as "${aws_instance.foo.ami}"
type ResourceVariable struct {
Mode ResourceMode
Type string // Resource type, i.e. "aws_instance"
Name string // Resource name
Field string // Resource field
Multi bool // True if multi-variable: aws_instance.foo.*.id
Index int // Index for multi-variable: aws_instance.foo.1.id == 1
key string
}
// SelfVariable is a variable that is referencing the same resource
// it is running on: "${self.address}"
type SelfVariable struct {
Field string
key string
}
// SimpleVariable is an unprefixed variable, which can show up when users have
// strings they are passing down to resources that use interpolation
// internally. The template_file resource is an example of this.
type SimpleVariable struct {
Key string
}
// TerraformVariable is a "terraform."-prefixed variable used to access
// metadata about the Terraform run.
type TerraformVariable struct {
Field string
key string
}
// A UserVariable is a variable that is referencing a user variable
// that is inputted from outside the configuration. This looks like
// "${var.foo}"
type UserVariable struct {
Name string
Elem string
key string
}
func NewInterpolatedVariable(v string) (InterpolatedVariable, error) {
if strings.HasPrefix(v, "count.") {
return NewCountVariable(v)
} else if strings.HasPrefix(v, "path.") {
return NewPathVariable(v)
} else if strings.HasPrefix(v, "self.") {
return NewSelfVariable(v)
} else if strings.HasPrefix(v, "terraform.") {
return NewTerraformVariable(v)
} else if strings.HasPrefix(v, "var.") {
return NewUserVariable(v)
} else if strings.HasPrefix(v, "module.") {
return NewModuleVariable(v)
} else if !strings.ContainsRune(v, '.') {
return NewSimpleVariable(v)
} else {
return NewResourceVariable(v)
}
}
func NewCountVariable(key string) (*CountVariable, error) {
var fieldType CountValueType
parts := strings.SplitN(key, ".", 2)
switch parts[1] {
case "index":
fieldType = CountValueIndex
}
return &CountVariable{
Type: fieldType,
key: key,
}, nil
}
func (c *CountVariable) FullKey() string {
return c.key
}
func NewModuleVariable(key string) (*ModuleVariable, error) {
parts := strings.SplitN(key, ".", 3)
if len(parts) < 3 {
return nil, fmt.Errorf(
"%s: module variables must be three parts: module.name.attr",
key)
}
return &ModuleVariable{
Name: parts[1],
Field: parts[2],
key: key,
}, nil
}
func (v *ModuleVariable) FullKey() string {
return v.key
}
func (v *ModuleVariable) GoString() string {
return fmt.Sprintf("*%#v", *v)
}
func NewPathVariable(key string) (*PathVariable, error) {
var fieldType PathValueType
parts := strings.SplitN(key, ".", 2)
switch parts[1] {
case "cwd":
fieldType = PathValueCwd
case "module":
fieldType = PathValueModule
case "root":
fieldType = PathValueRoot
}
return &PathVariable{
Type: fieldType,
key: key,
}, nil
}
func (v *PathVariable) FullKey() string {
return v.key
}
func NewResourceVariable(key string) (*ResourceVariable, error) {
var mode ResourceMode
var parts []string
if strings.HasPrefix(key, "data.") {
mode = DataResourceMode
parts = strings.SplitN(key, ".", 4)
if len(parts) < 4 {
return nil, fmt.Errorf(
"%s: data variables must be four parts: data.TYPE.NAME.ATTR",
key)
}
// Don't actually need the "data." prefix for parsing, since it's
// always constant.
parts = parts[1:]
} else {
mode = ManagedResourceMode
parts = strings.SplitN(key, ".", 3)
if len(parts) < 3 {
return nil, fmt.Errorf(
"%s: resource variables must be three parts: TYPE.NAME.ATTR",
key)
}
}
field := parts[2]
multi := false
var index int
if idx := strings.Index(field, "."); idx != -1 {
indexStr := field[:idx]
multi = indexStr == "*"
index = -1
if !multi {
indexInt, err := strconv.ParseInt(indexStr, 0, 0)
if err == nil {
multi = true
index = int(indexInt)
}
}
if multi {
field = field[idx+1:]
}
}
return &ResourceVariable{
Mode: mode,
Type: parts[0],
Name: parts[1],
Field: field,
Multi: multi,
Index: index,
key: key,
}, nil
}
func (v *ResourceVariable) ResourceId() string {
switch v.Mode {
case ManagedResourceMode:
return fmt.Sprintf("%s.%s", v.Type, v.Name)
case DataResourceMode:
return fmt.Sprintf("data.%s.%s", v.Type, v.Name)
default:
panic(fmt.Errorf("unknown resource mode %s", v.Mode))
}
}
func (v *ResourceVariable) FullKey() string {
return v.key
}
func NewSelfVariable(key string) (*SelfVariable, error) {
field := key[len("self."):]
return &SelfVariable{
Field: field,
key: key,
}, nil
}
func (v *SelfVariable) FullKey() string {
return v.key
}
func (v *SelfVariable) GoString() string {
return fmt.Sprintf("*%#v", *v)
}
func NewSimpleVariable(key string) (*SimpleVariable, error) {
return &SimpleVariable{key}, nil
}
func (v *SimpleVariable) FullKey() string {
return v.Key
}
func (v *SimpleVariable) GoString() string {
return fmt.Sprintf("*%#v", *v)
}
func NewTerraformVariable(key string) (*TerraformVariable, error) {
field := key[len("terraform."):]
return &TerraformVariable{
Field: field,
key: key,
}, nil
}
func (v *TerraformVariable) FullKey() string {
return v.key
}
func (v *TerraformVariable) GoString() string {
return fmt.Sprintf("*%#v", *v)
}
func NewUserVariable(key string) (*UserVariable, error) {
name := key[len("var."):]
elem := ""
if idx := strings.Index(name, "."); idx > -1 {
elem = name[idx+1:]
name = name[:idx]
}
if len(elem) > 0 {
return nil, fmt.Errorf("Invalid dot index found: 'var.%s.%s'. Values in maps and lists can be referenced using square bracket indexing, like: 'var.mymap[\"key\"]' or 'var.mylist[1]'.", name, elem)
}
return &UserVariable{
key: key,
Name: name,
Elem: elem,
}, nil
}
func (v *UserVariable) FullKey() string {
return v.key
}
func (v *UserVariable) GoString() string {
return fmt.Sprintf("*%#v", *v)
}
// DetectVariables takes an AST root and returns all the interpolated
// variables that are detected in the AST tree.
func DetectVariables(root ast.Node) ([]InterpolatedVariable, error) {
var result []InterpolatedVariable
var resultErr error
// Visitor callback
fn := func(n ast.Node) ast.Node {
if resultErr != nil {
return n
}
switch vn := n.(type) {
case *ast.VariableAccess:
v, err := NewInterpolatedVariable(vn.Name)
if err != nil {
resultErr = err
return n
}
result = append(result, v)
case *ast.Index:
if va, ok := vn.Target.(*ast.VariableAccess); ok {
v, err := NewInterpolatedVariable(va.Name)
if err != nil {
resultErr = err
return n
}
result = append(result, v)
}
if va, ok := vn.Key.(*ast.VariableAccess); ok {
v, err := NewInterpolatedVariable(va.Name)
if err != nil {
resultErr = err
return n
}
result = append(result, v)
}
default:
return n
}
return n
}
// Visitor pattern
root.Accept(fn)
if resultErr != nil {
return nil, resultErr
}
return result, nil
}
