Merge #4955: "terraform fmt" command

CHANGELOG.md

@@ -7,7 +7,8 @@ FEATURES:
  * **New resource:** `aws_iam_user_ssh_key` [GH-5774]
  * **New resource:** `triton_fabric` [GH-5920]
  * **New resource:** `triton_vlan` [GH-5920]
- 
+ * New `terraform fmt` command to automatically normalize config file style [GH-4955]
+
 IMPROVEMENTS:
 
  * provider/aws: Change `aws_elb` access_logs to list type [GH-5065]

Godeps/Godeps.json

@@ -712,10 +712,18 @@
 			"ImportPath": "github.com/hashicorp/hcl/hcl/ast",
 			"Rev": "2604f3bda7e8960c1be1063709e7d7f0765048d0"
 		},
+		{
+			"ImportPath": "github.com/hashicorp/hcl/hcl/fmtcmd",
+			"Rev": "71c7409f1abba841e528a80556ed2c67671744c3"
+		},
 		{
 			"ImportPath": "github.com/hashicorp/hcl/hcl/parser",
 			"Rev": "2604f3bda7e8960c1be1063709e7d7f0765048d0"
 		},
+		{
+			"ImportPath": "github.com/hashicorp/hcl/hcl/printer",
+			"Rev": "71c7409f1abba841e528a80556ed2c67671744c3"
+		},
 		{
 			"ImportPath": "github.com/hashicorp/hcl/hcl/scanner",
 			"Rev": "2604f3bda7e8960c1be1063709e7d7f0765048d0"

command/fmt.go

@@ -0,0 +1,94 @@
+package command
+
+import (
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+
+	"github.com/hashicorp/hcl/hcl/fmtcmd"
+	"github.com/mitchellh/cli"
+)
+
+const (
+	stdinArg      = "-"
+	fileExtension = "tf"
+)
+
+// FmtCommand is a Command implementation that rewrites Terraform config
+// files to a canonical format and style.
+type FmtCommand struct {
+	Meta
+	opts  fmtcmd.Options
+	input io.Reader // STDIN if nil
+}
+
+func (c *FmtCommand) Run(args []string) int {
+	if c.input == nil {
+		c.input = os.Stdin
+	}
+
+	args = c.Meta.process(args, false)
+
+	cmdFlags := flag.NewFlagSet("fmt", flag.ContinueOnError)
+	cmdFlags.BoolVar(&c.opts.List, "list", true, "list")
+	cmdFlags.BoolVar(&c.opts.Write, "write", true, "write")
+	cmdFlags.BoolVar(&c.opts.Diff, "diff", false, "diff")
+	cmdFlags.Usage = func() { c.Ui.Error(c.Help()) }
+
+	if err := cmdFlags.Parse(args); err != nil {
+		return 1
+	}
+
+	args = cmdFlags.Args()
+	if len(args) > 1 {
+		c.Ui.Error("The fmt command expects at most one argument.")
+		cmdFlags.Usage()
+		return 1
+	}
+
+	var dirs []string
+	if len(args) == 0 {
+		dirs = []string{"."}
+	} else if args[0] == stdinArg {
+		c.opts.List = false
+		c.opts.Write = false
+	} else {
+		dirs = []string{args[0]}
+	}
+
+	output := &cli.UiWriter{Ui: c.Ui}
+	err := fmtcmd.Run(dirs, []string{fileExtension}, c.input, output, c.opts)
+	if err != nil {
+		c.Ui.Error(fmt.Sprintf("Error running fmt: %s", err))
+		return 2
+	}
+
+	return 0
+}
+
+func (c *FmtCommand) Help() string {
+	helpText := `
+Usage: terraform fmt [options] [DIR]
+
+	Rewrites all Terraform configuration files to a canonical format.
+
+	If DIR is not specified then the current working directory will be used.
+	If DIR is "-" then content will be read from STDIN.
+
+Options:
+
+  -list            List files whose formatting differs (disabled if using STDIN)
+
+  -write           Write result to source file instead of STDOUT (disabled if using STDIN)
+
+  -diff            Display diffs instead of rewriting files
+
+`
+	return strings.TrimSpace(helpText)
+}
+
+func (c *FmtCommand) Synopsis() string {
+	return "Rewrites config files to canonical format"
+}

command/fmt_test.go

@@ -0,0 +1,206 @@
+package command
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/mitchellh/cli"
+)
+
+func TestFmt_errorReporting(t *testing.T) {
+	tempDir, err := fmtFixtureWriteDir()
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	defer os.RemoveAll(tempDir)
+
+	ui := new(cli.MockUi)
+	c := &FmtCommand{
+		Meta: Meta{
+			ContextOpts: testCtxConfig(testProvider()),
+			Ui:          ui,
+		},
+	}
+
+	dummy_file := filepath.Join(tempDir, "doesnotexist")
+	args := []string{dummy_file}
+	if code := c.Run(args); code != 2 {
+		t.Fatalf("wrong exit code. errors: \n%s", ui.ErrorWriter.String())
+	}
+
+	expected := fmt.Sprintf("Error running fmt: stat %s: no such file or directory", dummy_file)
+	if actual := ui.ErrorWriter.String(); !strings.Contains(actual, expected) {
+		t.Fatalf("expected:\n%s\n\nto include: %q", actual, expected)
+	}
+}
+
+func TestFmt_tooManyArgs(t *testing.T) {
+	ui := new(cli.MockUi)
+	c := &FmtCommand{
+		Meta: Meta{
+			ContextOpts: testCtxConfig(testProvider()),
+			Ui:          ui,
+		},
+	}
+
+	args := []string{
+		"one",
+		"two",
+	}
+	if code := c.Run(args); code != 1 {
+		t.Fatalf("wrong exit code. errors: \n%s", ui.ErrorWriter.String())
+	}
+
+	expected := "The fmt command expects at most one argument."
+	if actual := ui.ErrorWriter.String(); !strings.Contains(actual, expected) {
+		t.Fatalf("expected:\n%s\n\nto include: %q", actual, expected)
+	}
+}
+
+func TestFmt_workingDirectory(t *testing.T) {
+	tempDir, err := fmtFixtureWriteDir()
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	defer os.RemoveAll(tempDir)
+
+	cwd, err := os.Getwd()
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	err = os.Chdir(tempDir)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	defer os.Chdir(cwd)
+
+	ui := new(cli.MockUi)
+	c := &FmtCommand{
+		Meta: Meta{
+			ContextOpts: testCtxConfig(testProvider()),
+			Ui:          ui,
+		},
+	}
+
+	args := []string{}
+	if code := c.Run(args); code != 0 {
+		t.Fatalf("wrong exit code. errors: \n%s", ui.ErrorWriter.String())
+	}
+
+	expected := fmt.Sprintf("%s\n", fmtFixture.filename)
+	if actual := ui.OutputWriter.String(); actual != expected {
+		t.Fatalf("got: %q\nexpected: %q", actual, expected)
+	}
+}
+
+func TestFmt_directoryArg(t *testing.T) {
+	tempDir, err := fmtFixtureWriteDir()
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	defer os.RemoveAll(tempDir)
+
+	ui := new(cli.MockUi)
+	c := &FmtCommand{
+		Meta: Meta{
+			ContextOpts: testCtxConfig(testProvider()),
+			Ui:          ui,
+		},
+	}
+
+	args := []string{tempDir}
+	if code := c.Run(args); code != 0 {
+		t.Fatalf("wrong exit code. errors: \n%s", ui.ErrorWriter.String())
+	}
+
+	expected := fmt.Sprintf("%s\n", filepath.Join(tempDir, fmtFixture.filename))
+	if actual := ui.OutputWriter.String(); actual != expected {
+		t.Fatalf("got: %q\nexpected: %q", actual, expected)
+	}
+}
+
+func TestFmt_stdinArg(t *testing.T) {
+	input := new(bytes.Buffer)
+	input.Write(fmtFixture.input)
+
+	ui := new(cli.MockUi)
+	c := &FmtCommand{
+		Meta: Meta{
+			ContextOpts: testCtxConfig(testProvider()),
+			Ui:          ui,
+		},
+		input: input,
+	}
+
+	args := []string{"-"}
+	if code := c.Run(args); code != 0 {
+		t.Fatalf("wrong exit code. errors: \n%s", ui.ErrorWriter.String())
+	}
+
+	expected := fmtFixture.golden
+	if actual := ui.OutputWriter.Bytes(); !bytes.Equal(actual, expected) {
+		t.Fatalf("got: %q\nexpected: %q", actual, expected)
+	}
+}
+
+func TestFmt_nonDefaultOptions(t *testing.T) {
+	tempDir, err := fmtFixtureWriteDir()
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	defer os.RemoveAll(tempDir)
+
+	ui := new(cli.MockUi)
+	c := &FmtCommand{
+		Meta: Meta{
+			ContextOpts: testCtxConfig(testProvider()),
+			Ui:          ui,
+		},
+	}
+
+	args := []string{
+		"-list=false",
+		"-write=false",
+		"-diff",
+		tempDir,
+	}
+	if code := c.Run(args); code != 0 {
+		t.Fatalf("wrong exit code. errors: \n%s", ui.ErrorWriter.String())
+	}
+
+	expected := fmt.Sprintf("-%s+%s", fmtFixture.input, fmtFixture.golden)
+	if actual := ui.OutputWriter.String(); !strings.Contains(actual, expected) {
+		t.Fatalf("expected:\n%s\n\nto include: %q", actual, expected)
+	}
+}
+
+var fmtFixture = struct {
+	filename      string
+	input, golden []byte
+}{
+	"main.tf",
+	[]byte(`  foo  =  "bar"
+`),
+	[]byte(`foo = "bar"
+`),
+}
+
+func fmtFixtureWriteDir() (string, error) {
+	dir, err := ioutil.TempDir("", "tf")
+	if err != nil {
+		return "", err
+	}
+
+	err = ioutil.WriteFile(filepath.Join(dir, fmtFixture.filename), fmtFixture.input, 0644)
+	if err != nil {
+		os.RemoveAll(dir)
+		return "", err
+	}
+
+	return dir, nil
+}

commands.go

@@ -50,6 +50,12 @@ func init() {
 			}, nil
 		},
 
+		"fmt": func() (cli.Command, error) {
+			return &command.FmtCommand{
+				Meta: meta,
+			}, nil
+		},
+
 		"get": func() (cli.Command, error) {
 			return &command.GetCommand{
 				Meta: meta,

vendor/github.com/hashicorp/hcl/hcl/fmtcmd/fmtcmd.go

@@ -0,0 +1,164 @@
+// Derivative work from:
+//	- https://golang.org/src/cmd/gofmt/gofmt.go
+//	- https://github.com/fatih/hclfmt
+
+package fmtcmd
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+
+	"github.com/hashicorp/hcl/hcl/printer"
+)
+
+var (
+	ErrWriteStdin = errors.New("cannot use write option with standard input")
+)
+
+type Options struct {
+	List  bool // list files whose formatting differs
+	Write bool // write result to (source) file instead of stdout
+	Diff  bool // display diffs instead of rewriting files
+}
+
+func isValidFile(f os.FileInfo, extensions []string) bool {
+	if !f.IsDir() && !strings.HasPrefix(f.Name(), ".") {
+		for _, ext := range extensions {
+			if strings.HasSuffix(f.Name(), "."+ext) {
+				return true
+			}
+		}
+	}
+
+	return false
+}
+
+// If in == nil, the source is the contents of the file with the given filename.
+func processFile(filename string, in io.Reader, out io.Writer, stdin bool, opts Options) error {
+	if in == nil {
+		f, err := os.Open(filename)
+		if err != nil {
+			return err
+		}
+		defer f.Close()
+		in = f
+	}
+
+	src, err := ioutil.ReadAll(in)
+	if err != nil {
+		return err
+	}
+
+	res, err := printer.Format(src)
+	if err != nil {
+		return err
+	}
+	// Files should end with newlines
+	res = append(res, []byte("\n")...)
+
+	if !bytes.Equal(src, res) {
+		// formatting has changed
+		if opts.List {
+			fmt.Fprintln(out, filename)
+		}
+		if opts.Write {
+			err = ioutil.WriteFile(filename, res, 0644)
+			if err != nil {
+				return err
+			}
+		}
+		if opts.Diff {
+			data, err := diff(src, res)
+			if err != nil {
+				return fmt.Errorf("computing diff: %s", err)
+			}
+			fmt.Fprintf(out, "diff a/%s b/%s\n", filename, filename)
+			out.Write(data)
+		}
+	}
+
+	if !opts.List && !opts.Write && !opts.Diff {
+		_, err = out.Write(res)
+	}
+
+	return err
+}
+
+func walkDir(path string, extensions []string, stdout io.Writer, opts Options) error {
+	visitFile := func(path string, f os.FileInfo, err error) error {
+		if err == nil && isValidFile(f, extensions) {
+			err = processFile(path, nil, stdout, false, opts)
+		}
+		return err
+	}
+
+	return filepath.Walk(path, visitFile)
+}
+
+func Run(
+	paths, extensions []string,
+	stdin io.Reader,
+	stdout io.Writer,
+	opts Options,
+) error {
+	if len(paths) == 0 {
+		if opts.Write {
+			return ErrWriteStdin
+		}
+		if err := processFile("<standard input>", stdin, stdout, true, opts); err != nil {
+			return err
+		}
+		return nil
+	}
+
+	for _, path := range paths {
+		switch dir, err := os.Stat(path); {
+		case err != nil:
+			return err
+		case dir.IsDir():
+			if err := walkDir(path, extensions, stdout, opts); err != nil {
+				return err
+			}
+		default:
+			if err := processFile(path, nil, stdout, false, opts); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
+func diff(b1, b2 []byte) (data []byte, err error) {
+	f1, err := ioutil.TempFile("", "")
+	if err != nil {
+		return
+	}
+	defer os.Remove(f1.Name())
+	defer f1.Close()
+
+	f2, err := ioutil.TempFile("", "")
+	if err != nil {
+		return
+	}
+	defer os.Remove(f2.Name())
+	defer f2.Close()
+
+	f1.Write(b1)
+	f2.Write(b2)
+
+	data, err = exec.Command("diff", "-u", f1.Name(), f2.Name()).CombinedOutput()
+	if len(data) > 0 {
+		// diff exits with a non-zero status when the files don't match.
+		// Ignore that failure as long as we get output.
+		err = nil
+	}
+	return
+}

vendor/github.com/hashicorp/hcl/hcl/printer/nodes.go

@@ -0,0 +1,575 @@
+package printer
+
+import (
+	"bytes"
+	"fmt"
+	"sort"
+
+	"github.com/hashicorp/hcl/hcl/ast"
+	"github.com/hashicorp/hcl/hcl/token"
+)
+
+const (
+	blank    = byte(' ')
+	newline  = byte('\n')
+	tab      = byte('\t')
+	infinity = 1 << 30 // offset or line
+)
+
+var (
+	unindent = []byte("\uE123") // in the private use space
+)
+
+type printer struct {
+	cfg  Config
+	prev token.Pos
+
+	comments           []*ast.CommentGroup // may be nil, contains all comments
+	standaloneComments []*ast.CommentGroup // contains all standalone comments (not assigned to any node)
+
+	enableTrace bool
+	indentTrace int
+}
+
+type ByPosition []*ast.CommentGroup
+
+func (b ByPosition) Len() int           { return len(b) }
+func (b ByPosition) Swap(i, j int)      { b[i], b[j] = b[j], b[i] }
+func (b ByPosition) Less(i, j int) bool { return b[i].Pos().Before(b[j].Pos()) }
+
+// collectComments comments all standalone comments which are not lead or line
+// comment
+func (p *printer) collectComments(node ast.Node) {
+	// first collect all comments. This is already stored in
+	// ast.File.(comments)
+	ast.Walk(node, func(nn ast.Node) (ast.Node, bool) {
+		switch t := nn.(type) {
+		case *ast.File:
+			p.comments = t.Comments
+			return nn, false
+		}
+		return nn, true
+	})
+
+	standaloneComments := make(map[token.Pos]*ast.CommentGroup, 0)
+	for _, c := range p.comments {
+		standaloneComments[c.Pos()] = c
+	}
+
+	// next remove all lead and line comments from the overall comment map.
+	// This will give us comments which are standalone, comments which are not
+	// assigned to any kind of node.
+	ast.Walk(node, func(nn ast.Node) (ast.Node, bool) {
+		switch t := nn.(type) {
+		case *ast.LiteralType:
+			if t.LineComment != nil {
+				for _, comment := range t.LineComment.List {
+					if _, ok := standaloneComments[comment.Pos()]; ok {
+						delete(standaloneComments, comment.Pos())
+					}
+				}
+			}
+		case *ast.ObjectItem:
+			if t.LeadComment != nil {
+				for _, comment := range t.LeadComment.List {
+					if _, ok := standaloneComments[comment.Pos()]; ok {
+						delete(standaloneComments, comment.Pos())
+					}
+				}
+			}
+
+			if t.LineComment != nil {
+				for _, comment := range t.LineComment.List {
+					if _, ok := standaloneComments[comment.Pos()]; ok {
+						delete(standaloneComments, comment.Pos())
+					}
+				}
+			}
+		}
+
+		return nn, true
+	})
+
+	for _, c := range standaloneComments {
+		p.standaloneComments = append(p.standaloneComments, c)
+	}
+
+	sort.Sort(ByPosition(p.standaloneComments))
+
+}
+
+// output prints creates b printable HCL output and returns it.
+func (p *printer) output(n interface{}) []byte {
+	var buf bytes.Buffer
+
+	switch t := n.(type) {
+	case *ast.File:
+		return p.output(t.Node)
+	case *ast.ObjectList:
+		var index int
+		var nextItem token.Pos
+		var commented bool
+		for {
+			// TODO(arslan): refactor below comment printing, we have the same in objectType
+			for _, c := range p.standaloneComments {
+				for _, comment := range c.List {
+					if index != len(t.Items) {
+						nextItem = t.Items[index].Pos()
+					} else {
+						nextItem = token.Pos{Offset: infinity, Line: infinity}
+					}
+
+					if comment.Pos().After(p.prev) && comment.Pos().Before(nextItem) {
+						// if we hit the end add newlines so we can print the comment
+						if index == len(t.Items) {
+							buf.Write([]byte{newline, newline})
+						}
+
+						buf.WriteString(comment.Text)
+
+						buf.WriteByte(newline)
+						if index != len(t.Items) {
+							buf.WriteByte(newline)
+						}
+					}
+				}
+			}
+
+			if index == len(t.Items) {
+				break
+			}
+
+			buf.Write(p.output(t.Items[index]))
+			if !commented && index != len(t.Items)-1 {
+				buf.Write([]byte{newline, newline})
+			}
+			index++
+		}
+	case *ast.ObjectKey:
+		buf.WriteString(t.Token.Text)
+	case *ast.ObjectItem:
+		p.prev = t.Pos()
+		buf.Write(p.objectItem(t))
+	case *ast.LiteralType:
+		buf.Write(p.literalType(t))
+	case *ast.ListType:
+		buf.Write(p.list(t))
+	case *ast.ObjectType:
+		buf.Write(p.objectType(t))
+	default:
+		fmt.Printf(" unknown type: %T\n", n)
+	}
+
+	return buf.Bytes()
+}
+
+func (p *printer) literalType(lit *ast.LiteralType) []byte {
+	result := []byte(lit.Token.Text)
+	if lit.Token.Type == token.HEREDOC {
+		// Clear the trailing newline from heredocs
+		if result[len(result)-1] == '\n' {
+			result = result[:len(result)-1]
+		}
+
+		// Poison lines 2+ so that we don't indent them
+		result = p.heredocIndent(result)
+	}
+
+	return result
+}
+
+// objectItem returns the printable HCL form of an object item. An object type
+// starts with one/multiple keys and has a value. The value might be of any
+// type.
+func (p *printer) objectItem(o *ast.ObjectItem) []byte {
+	defer un(trace(p, fmt.Sprintf("ObjectItem: %s", o.Keys[0].Token.Text)))
+	var buf bytes.Buffer
+
+	if o.LeadComment != nil {
+		for _, comment := range o.LeadComment.List {
+			buf.WriteString(comment.Text)
+			buf.WriteByte(newline)
+		}
+	}
+
+	for i, k := range o.Keys {
+		buf.WriteString(k.Token.Text)
+		buf.WriteByte(blank)
+
+		// reach end of key
+		if o.Assign.IsValid() && i == len(o.Keys)-1 && len(o.Keys) == 1 {
+			buf.WriteString("=")
+			buf.WriteByte(blank)
+		}
+	}
+
+	buf.Write(p.output(o.Val))
+
+	if o.Val.Pos().Line == o.Keys[0].Pos().Line && o.LineComment != nil {
+		buf.WriteByte(blank)
+		for _, comment := range o.LineComment.List {
+			buf.WriteString(comment.Text)
+		}
+	}
+
+	return buf.Bytes()
+}
+
+// objectType returns the printable HCL form of an object type. An object type
+// begins with a brace and ends with a brace.
+func (p *printer) objectType(o *ast.ObjectType) []byte {
+	defer un(trace(p, "ObjectType"))
+	var buf bytes.Buffer
+	buf.WriteString("{")
+	buf.WriteByte(newline)
+
+	var index int
+	var nextItem token.Pos
+	var commented bool
+	for {
+		// Print stand alone comments
+		for _, c := range p.standaloneComments {
+			for _, comment := range c.List {
+				// if we hit the end, last item should be the brace
+				if index != len(o.List.Items) {
+					nextItem = o.List.Items[index].Pos()
+				} else {
+					nextItem = o.Rbrace
+				}
+
+				if comment.Pos().After(p.prev) && comment.Pos().Before(nextItem) {
+					// add newline if it's between other printed nodes
+					if index > 0 {
+						commented = true
+						buf.WriteByte(newline)
+					}
+
+					buf.Write(p.indent([]byte(comment.Text)))
+					buf.WriteByte(newline)
+					if index != len(o.List.Items) {
+						buf.WriteByte(newline) // do not print on the end
+					}
+				}
+			}
+		}
+
+		if index == len(o.List.Items) {
+			p.prev = o.Rbrace
+			break
+		}
+
+		// check if we have adjacent one liner items. If yes we'll going to align
+		// the comments.
+		var aligned []*ast.ObjectItem
+		for _, item := range o.List.Items[index:] {
+			// we don't group one line lists
+			if len(o.List.Items) == 1 {
+				break
+			}
+
+			// one means a oneliner with out any lead comment
+			// two means a oneliner with lead comment
+			// anything else might be something else
+			cur := lines(string(p.objectItem(item)))
+			if cur > 2 {
+				break
+			}
+
+			curPos := item.Pos()
+
+			nextPos := token.Pos{}
+			if index != len(o.List.Items)-1 {
+				nextPos = o.List.Items[index+1].Pos()
+			}
+
+			prevPos := token.Pos{}
+			if index != 0 {
+				prevPos = o.List.Items[index-1].Pos()
+			}
+
+			// fmt.Println("DEBUG ----------------")
+			// fmt.Printf("prev = %+v prevPos: %s\n", prev, prevPos)
+			// fmt.Printf("cur = %+v curPos: %s\n", cur, curPos)
+			// fmt.Printf("next = %+v nextPos: %s\n", next, nextPos)
+
+			if curPos.Line+1 == nextPos.Line {
+				aligned = append(aligned, item)
+				index++
+				continue
+			}
+
+			if curPos.Line-1 == prevPos.Line {
+				aligned = append(aligned, item)
+				index++
+
+				// finish if we have a new line or comment next. This happens
+				// if the next item is not adjacent
+				if curPos.Line+1 != nextPos.Line {
+					break
+				}
+				continue
+			}
+
+			break
+		}
+
+		// put newlines if the items are between other non aligned items.
+		// newlines are also added if there is a standalone comment already, so
+		// check it too
+		if !commented && index != len(aligned) {
+			buf.WriteByte(newline)
+		}
+
+		if len(aligned) >= 1 {
+			p.prev = aligned[len(aligned)-1].Pos()
+
+			items := p.alignedItems(aligned)
+			buf.Write(p.indent(items))
+		} else {
+			p.prev = o.List.Items[index].Pos()
+
+			buf.Write(p.indent(p.objectItem(o.List.Items[index])))
+			index++
+		}
+
+		buf.WriteByte(newline)
+	}
+
+	buf.WriteString("}")
+	return buf.Bytes()
+}
+
+func (p *printer) alignedItems(items []*ast.ObjectItem) []byte {
+	var buf bytes.Buffer
+
+	// find the longest key and value length, needed for alignment
+	var longestKeyLen int // longest key length
+	var longestValLen int // longest value length
+	for _, item := range items {
+		key := len(item.Keys[0].Token.Text)
+		val := len(p.output(item.Val))
+
+		if key > longestKeyLen {
+			longestKeyLen = key
+		}
+
+		if val > longestValLen {
+			longestValLen = val
+		}
+	}
+
+	for i, item := range items {
+		if item.LeadComment != nil {
+			for _, comment := range item.LeadComment.List {
+				buf.WriteString(comment.Text)
+				buf.WriteByte(newline)
+			}
+		}
+
+		for i, k := range item.Keys {
+			keyLen := len(k.Token.Text)
+			buf.WriteString(k.Token.Text)
+			for i := 0; i < longestKeyLen-keyLen+1; i++ {
+				buf.WriteByte(blank)
+			}
+
+			// reach end of key
+			if i == len(item.Keys)-1 && len(item.Keys) == 1 {
+				buf.WriteString("=")
+				buf.WriteByte(blank)
+			}
+		}
+
+		val := p.output(item.Val)
+		valLen := len(val)
+		buf.Write(val)
+
+		if item.Val.Pos().Line == item.Keys[0].Pos().Line && item.LineComment != nil {
+			for i := 0; i < longestValLen-valLen+1; i++ {
+				buf.WriteByte(blank)
+			}
+
+			for _, comment := range item.LineComment.List {
+				buf.WriteString(comment.Text)
+			}
+		}
+
+		// do not print for the last item
+		if i != len(items)-1 {
+			buf.WriteByte(newline)
+		}
+	}
+
+	return buf.Bytes()
+}
+
+// list returns the printable HCL form of an list type.
+func (p *printer) list(l *ast.ListType) []byte {
+	var buf bytes.Buffer
+	buf.WriteString("[")
+
+	var longestLine int
+	for _, item := range l.List {
+		// for now we assume that the list only contains literal types
+		if lit, ok := item.(*ast.LiteralType); ok {
+			lineLen := len(lit.Token.Text)
+			if lineLen > longestLine {
+				longestLine = lineLen
+			}
+		}
+	}
+
+	insertSpaceBeforeItem := false
+	for i, item := range l.List {
+		if item.Pos().Line != l.Lbrack.Line {
+			// multiline list, add newline before we add each item
+			buf.WriteByte(newline)
+			insertSpaceBeforeItem = false
+			// also indent each line
+			val := p.output(item)
+			curLen := len(val)
+			buf.Write(p.indent(val))
+			buf.WriteString(",")
+
+			if lit, ok := item.(*ast.LiteralType); ok && lit.LineComment != nil {
+				// if the next item doesn't have any comments, do not align
+				buf.WriteByte(blank) // align one space
+				for i := 0; i < longestLine-curLen; i++ {
+					buf.WriteByte(blank)
+				}
+
+				for _, comment := range lit.LineComment.List {
+					buf.WriteString(comment.Text)
+				}
+			}
+
+			if i == len(l.List)-1 {
+				buf.WriteByte(newline)
+			}
+		} else {
+			if insertSpaceBeforeItem {
+				buf.WriteByte(blank)
+				insertSpaceBeforeItem = false
+			}
+			buf.Write(p.output(item))
+			if i != len(l.List)-1 {
+				buf.WriteString(",")
+				insertSpaceBeforeItem = true
+			}
+		}
+
+	}
+
+	buf.WriteString("]")
+	return buf.Bytes()
+}
+
+// indent indents the lines of the given buffer for each non-empty line
+func (p *printer) indent(buf []byte) []byte {
+	var prefix []byte
+	if p.cfg.SpacesWidth != 0 {
+		for i := 0; i < p.cfg.SpacesWidth; i++ {
+			prefix = append(prefix, blank)
+		}
+	} else {
+		prefix = []byte{tab}
+	}
+
+	var res []byte
+	bol := true
+	for _, c := range buf {
+		if bol && c != '\n' {
+			res = append(res, prefix...)
+		}
+
+		res = append(res, c)
+		bol = c == '\n'
+	}
+	return res
+}
+
+// unindent removes all the indentation from the tombstoned lines
+func (p *printer) unindent(buf []byte) []byte {
+	var res []byte
+	for i := 0; i < len(buf); i++ {
+		skip := len(buf)-i <= len(unindent)
+		if !skip {
+			skip = !bytes.Equal(unindent, buf[i:i+len(unindent)])
+		}
+		if skip {
+			res = append(res, buf[i])
+			continue
+		}
+
+		// We have a marker. we have to backtrace here and clean out
+		// any whitespace ahead of our tombstone up to a \n
+		for j := len(res) - 1; j >= 0; j-- {
+			if res[j] == '\n' {
+				break
+			}
+
+			res = res[:j]
+		}
+
+		// Skip the entire unindent marker
+		i += len(unindent) - 1
+	}
+
+	return res
+}
+
+// heredocIndent marks all the 2nd and further lines as unindentable
+func (p *printer) heredocIndent(buf []byte) []byte {
+	var res []byte
+	bol := false
+	for _, c := range buf {
+		if bol && c != '\n' {
+			res = append(res, unindent...)
+		}
+		res = append(res, c)
+		bol = c == '\n'
+	}
+	return res
+}
+
+func lines(txt string) int {
+	endline := 1
+	for i := 0; i < len(txt); i++ {
+		if txt[i] == '\n' {
+			endline++
+		}
+	}
+	return endline
+}
+
+// ----------------------------------------------------------------------------
+// Tracing support
+
+func (p *printer) printTrace(a ...interface{}) {
+	if !p.enableTrace {
+		return
+	}
+
+	const dots = ". . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . "
+	const n = len(dots)
+	i := 2 * p.indentTrace
+	for i > n {
+		fmt.Print(dots)
+		i -= n
+	}
+	// i <= n
+	fmt.Print(dots[0:i])
+	fmt.Println(a...)
+}
+
+func trace(p *printer, msg string) *printer {
+	p.printTrace(msg, "(")
+	p.indentTrace++
+	return p
+}
+
+// Usage pattern: defer un(trace(p, "..."))
+func un(p *printer) {
+	p.indentTrace--
+	p.printTrace(")")
+}

vendor/github.com/hashicorp/hcl/hcl/printer/printer.go

@@ -0,0 +1,64 @@
+// Package printer implements printing of AST nodes to HCL format.
+package printer
+
+import (
+	"bytes"
+	"io"
+	"text/tabwriter"
+
+	"github.com/hashicorp/hcl/hcl/ast"
+	"github.com/hashicorp/hcl/hcl/parser"
+)
+
+var DefaultConfig = Config{
+	SpacesWidth: 2,
+}
+
+// A Config node controls the output of Fprint.
+type Config struct {
+	SpacesWidth int // if set, it will use spaces instead of tabs for alignment
+}
+
+func (c *Config) Fprint(output io.Writer, node ast.Node) error {
+	p := &printer{
+		cfg:                *c,
+		comments:           make([]*ast.CommentGroup, 0),
+		standaloneComments: make([]*ast.CommentGroup, 0),
+		// enableTrace:        true,
+	}
+
+	p.collectComments(node)
+
+	if _, err := output.Write(p.unindent(p.output(node))); err != nil {
+		return err
+	}
+
+	// flush tabwriter, if any
+	var err error
+	if tw, _ := output.(*tabwriter.Writer); tw != nil {
+		err = tw.Flush()
+	}
+
+	return err
+}
+
+// Fprint "pretty-prints" an HCL node to output
+// It calls Config.Fprint with default settings.
+func Fprint(output io.Writer, node ast.Node) error {
+	return DefaultConfig.Fprint(output, node)
+}
+
+// Format formats src HCL and returns the result.
+func Format(src []byte) ([]byte, error) {
+	node, err := parser.Parse(src)
+	if err != nil {
+		return nil, err
+	}
+
+	var buf bytes.Buffer
+	if err := DefaultConfig.Fprint(&buf, node); err != nil {
+		return nil, err
+	}
+
+	return buf.Bytes(), nil
+}

website/source/docs/commands/fmt.html.markdown

@@ -0,0 +1,28 @@
+---
+layout: "docs"
+page_title: "Command: fmt"
+sidebar_current: "docs-commands-fmt"
+description: |-
+  The `terraform fmt` command is used to rewrite Terraform configuration files to a canonical format and style.
+---
+
+# Command: fmt
+
+The `terraform fmt` command is used to rewrite Terraform configuration files
+to a canonical format and style.
+
+## Usage
+
+Usage: `terraform fmt [options] [DIR]`
+
+By default, `fmt` scans the current directory for configuration files. If
+the `dir` argument is provided then it will scan that given directory
+instead. If `dir` is a single dash (`-`) then `fmt` will read from standard
+input (STDIN).
+
+The command-line flags are all optional. The list of available flags are:
+
+* `-list=true` - List files whose formatting differs (disabled if using STDIN)
+* `-write=true` - Write result to source file instead of STDOUT (disabled if
+    using STDIN)
+* `-diff=false` - Display diffs instead of rewriting files

website/source/layouts/docs.erb

@@ -67,6 +67,10 @@
 					<a href="/docs/commands/destroy.html">destroy</a>
 					</li>
 
+					<li<%= sidebar_current("docs-commands-fmt") %>>
+					<a href="/docs/commands/fmt.html">fmt</a>
+					</li>
+
 					<li<%= sidebar_current("docs-commands-get") %>>
 					<a href="/docs/commands/get.html">get</a>
 					</li>