Add shell completion

cli/app.go

@@ -50,7 +50,9 @@ func NewApp(writer io.Writer, errWriter io.Writer) *cli.App {
 	app.Version = version.GetVersion()
 	app.Writer = writer
 	app.ErrWriter = errWriter
-	app.Flags = commands.NewGlobalFlags(opts)
+	app.Flags = append(
+		commands.NewGlobalFlags(opts),
+		commands.NewHelpVersionFlags(opts)...)
 	app.Commands = append(
 		deprecatedCommands(opts),
 		terragruntCommands(opts)...)

cli/app_test.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
+	"strings"
 	"testing"
 
 	"github.com/gruntwork-io/go-commons/errors"
@@ -441,7 +442,9 @@ func runAppTest(args []string, opts *options.TerragruntOptions) (*options.Terrag
 	app := cli.NewApp()
 	app.Writer = &bytes.Buffer{}
 	app.ErrWriter = &bytes.Buffer{}
-	app.Flags = commands.NewGlobalFlags(opts)
+	app.Flags = append(
+		commands.NewGlobalFlags(opts),
+		commands.NewHelpVersionFlags(opts)...)
 	app.Commands = append(
 		deprecatedCommands(opts),
 		terragruntCommands...)
@@ -463,3 +466,41 @@ type argMissingValueError string
 func (err argMissingValueError) Error() string {
 	return fmt.Sprintf("flag needs an argument: -%s", string(err))
 }
+
+func TestAutocomplete(t *testing.T) {
+	defer os.Unsetenv("COMP_LINE")
+
+	testCases := []struct {
+		compLine          string
+		expectedCompletes []string
+	}{
+		{
+			"",
+			[]string{"aws-provider-patch", "graph-dependencies", "hclfmt", "output-module-groups", "render-json", "run-all", "terragrunt-info", "validate-inputs"},
+		},
+		{
+			"--versio",
+			[]string{"--version"},
+		},
+		{
+			"render-json -",
+			[]string{"--terragrunt-json-out", "--with-metadata"},
+		},
+		{
+			"run-all ren",
+			[]string{"render-json"},
+		},
+	}
+
+	for _, testCase := range testCases {
+		os.Setenv("COMP_LINE", "terragrunt "+testCase.compLine)
+
+		output := &bytes.Buffer{}
+		app := NewApp(output, os.Stderr)
+
+		err := app.Run([]string{"terragrunt"})
+		require.NoError(t, err)
+
+		assert.Contains(t, output.String(), strings.Join(testCase.expectedCompletes, "\n"))
+	}
+}

cli/commands/flags.go

@@ -242,13 +242,14 @@ func NewGlobalFlags(opts *options.TerragruntOptions) cli.Flags {
 
 	flags.Sort()
 
-	// add auxiliary flags after sorting to put the flag at the end of the flag list in the help.
-	flags.Add(
+	return flags
+}
+
+func NewHelpVersionFlags(opts *options.TerragruntOptions) cli.Flags {
+	return cli.Flags{
 		NewHelpFlag(opts),
 		NewVersionFlag(opts),
-	)
-
-	return flags
+	}
 }
 
 func NewHelpFlag(opts *options.TerragruntOptions) cli.Flag {

cli/commands/run-all/command.go

@@ -3,6 +3,7 @@ package runall
 import (
 	"sort"
 
+	"github.com/gruntwork-io/terragrunt/cli/commands"
 	awsproviderpatch "github.com/gruntwork-io/terragrunt/cli/commands/aws-provider-patch"
 	graphdependencies "github.com/gruntwork-io/terragrunt/cli/commands/graph-dependencies"
 	"github.com/gruntwork-io/terragrunt/cli/commands/hclfmt"
@@ -23,6 +24,7 @@ func NewCommand(opts *options.TerragruntOptions) *cli.Command {
 		Name:        CommandName,
 		Usage:       "Run a terraform command against a 'stack' by running the specified command in each subfolder.",
 		Description: "The command will recursively find terragrunt modules in the current directory tree and run the terraform command in dependency order (unless the command is destroy, in which case the command is run in reverse dependency order).",
+		Flags:       commands.NewGlobalFlags(opts),
 		Subcommands: subCommands(opts).SkipRunning(),
 		Action:      action(opts),
 	}

cli/commands/terraform/command.go

@@ -8,7 +8,8 @@ import (
 )
 
 const (
-	CommandName = "terraform"
+	CommandName     = ""
+	CommandHelpName = "*"
 )
 
 var (
@@ -18,7 +19,7 @@ var (
 func NewCommand(opts *options.TerragruntOptions) *cli.Command {
 	return &cli.Command{
 		Name:     CommandName,
-		HelpName: "*",
+		HelpName: CommandHelpName,
 		Usage:    "Terragrunt forwards all other commands directly to Terraform",
 		Action:   action(opts),
 	}

cli/deprecated_commands.go

@@ -55,7 +55,7 @@ func replaceDeprecatedCommandFunc(terragruntCommandName, terraformCommandName st
 				deprecatedCommandName,
 			)
 
-			err := command.Run(ctx, args...)
+			err := command.Run(ctx, args)
 			return err
 		}
 	}

docs/_docs/01_getting-started/install.md

@@ -32,6 +32,30 @@ If you  want the latest version, the recommended installation option is to [down
 
 * **FreeBSD**: You can install Terragrunt on FreeBSD using [Pkg](https://www.freebsd.org/cgi/man.cgi?pkg(7)): `pkg install terragrunt`.
 
+### Enable tab completion
+
+If you use either Bash or Zsh, you can enable tab completion for Terragrunt commands. To enable autocomplete, first ensure that a config file exists for your chosen shell.
+
+
+For Bash shell.
+``` shell
+touch ~/.bashrc
+```
+
+For Zsh shell.
+``` shell
+touch ~/.zshrc
+```
+
+Then install the autocomplete package.
+
+``` shell
+terragrunt --install-autocomplete
+```
+
+Once the autocomplete support is installed, you will need to restart your shell.
+
+
 ### Terragrunt GitHub Action
 
 Terragrunt is also available as a GitHub Action. Instructions on how to use it can be found at [https://github.com/gruntwork-io/terragrunt-action](https://github.com/gruntwork-io/terragrunt-action).

go.mod

@@ -140,6 +140,7 @@ require (
 	github.com/pierrec/lz4 v2.6.1+incompatible // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/posener/complete v1.2.3 // indirect
 	github.com/russross/blackfriday/v2 v2.1.0 // indirect
 	github.com/ryanuber/go-glob v1.0.0 // indirect
 	github.com/sourcegraph/go-lsp v0.0.0-20200429204803-219e11d77f5d // indirect

go.sum

@@ -844,6 +844,8 @@ github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZb
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/posener/complete v1.1.1/go.mod h1:em0nMJCgc9GFtwrmVmEMR/ZL6WyhyjMBndrE9hABlRI=
 github.com/posener/complete v1.2.1/go.mod h1:6gapUrK/U1TAN7ciCoNRIdVC5sbdBTUh1DKN0g6uH7E=
+github.com/posener/complete v1.2.3 h1:NP0eAhjcjImqslEwo/1hq7gpajME0fTLTezBKDqfXqo=
+github.com/posener/complete v1.2.3/go.mod h1:WZIdtGGp+qx0sLrYKtIRAruyNpv6hFCicSgv7Sy7s/s=
 github.com/pquerna/otp v1.2.1-0.20191009055518-468c2dd2b58d h1:PinQItctnaL2LtkaSM678+ZLLy5TajwOeXzWvYC7tII=
 github.com/pquerna/otp v1.2.1-0.20191009055518-468c2dd2b58d/go.mod h1:dkJfzwRKNiegxyNb54X/3fLwhCynbMspSyWKnvi1AEg=
 github.com/prometheus/client_golang v0.9.1/go.mod h1:7SWBe2y4D6OKWSNQJUaRYU/AaXPKyh/dDVn+NZz0KFw=

pkg/cli/app.go

@@ -4,6 +4,7 @@ import (
 	"os"
 	"strings"
 
+	"github.com/gruntwork-io/go-commons/errors"
 	"github.com/urfave/cli/v2"
 )
 
@@ -31,6 +32,8 @@ type App struct {
 	// The difference between `Before` is that `CommonBefore` runs only once for the target command, while `Before` is different for each command and is performed by each command.
 	// Useful when some steps need to to performed for all commands without exception, when all flags are parsed and the context contains the target command.
 	CommonBefore ActionFunc
+	// The function to call when checking for command completions
+	Complete CompleteFunc
 	// An action to execute before any subcommands are run, but after the context is ready
 	// If a non-nil error is returned, no subcommands are run
 	Before ActionFunc
@@ -43,13 +46,36 @@ type App struct {
 	DefaultCommand *Command
 	// OsExiter is the function used when the app exits. If not set defaults to os.Exit.
 	OsExiter func(code int)
+
+	// Autocomplete enables or disables subcommand auto-completion support.
+	// This is enabled by default when NewApp is called. Otherwise, this
+	// must enabled explicitly.
+	//
+	// Autocomplete requires the "Name" option to be set on CLI. This name
+	// should be set exactly to the binary name that is autocompleted.
+	Autocomplete bool
+
+	// AutocompleteInstallFlag and AutocompleteUninstallFlag are the global flag
+	// names for installing and uninstalling the autocompletion handlers
+	// for the user's shell. The flag should omit the hyphen(s) in front of
+	// the value. Both single and double hyphens will automatically be supported
+	// for the flag name. These default to `autocomplete-install` and
+	// `autocomplete-uninstall` respectively.
+	AutocompleteInstallFlag   string
+	AutocompleteUninstallFlag string
+
+	// Autocompletion is supported via the github.com/posener/complete
+	// library. This library supports bash, zsh and fish. To add support
+	// for other shells, please see that library.
+	AutocompleteInstaller AutocompleteInstaller
 }
 
 // NewApp returns app new App instance.
 func NewApp() *App {
 	return &App{
-		App:      cli.NewApp(),
-		OsExiter: os.Exit,
+		App:          cli.NewApp(),
+		OsExiter:     os.Exit,
+		Autocomplete: true,
 	}
 }
 
@@ -78,11 +104,27 @@ func (app *App) Run(arguments []string) error {
 	app.Authors = []*cli.Author{{Name: app.Author}}
 
 	app.App.Action = func(parentCtx *cli.Context) error {
-		args := parentCtx.Args().Slice()
+		cmd := app.newRootCommand()
+
+		args := Args(parentCtx.Args().Slice())
 		ctx := newContext(parentCtx.Context, app)
 
-		cmd := ctx.App.newRootCommand()
-		err := cmd.Run(ctx, args...)
+		if app.Autocomplete {
+			if err := app.setupAutocomplete(args); err != nil {
+				return app.handleExitCoder(err)
+			}
+
+			if compLine := os.Getenv(envCompleteLine); compLine != "" {
+				args = strings.Fields(compLine)
+				if args[0] == app.Name {
+					args = args[1:]
+				}
+
+				ctx.shellComplete = true
+			}
+		}
+
+		err := cmd.Run(ctx, args.Normalize(SingleDashFlag))
 		return err
 	}
 
@@ -113,10 +155,64 @@ func (app *App) newRootCommand() *Command {
 		Description: app.Description,
 		Flags:       app.Flags,
 		Subcommands: app.Commands,
+		Complete:    app.Complete,
 		IsRoot:      true,
 	}
 }
 
+func (app *App) setupAutocomplete(arguments []string) error {
+	var (
+		isAutocompleteInstall   bool
+		isAutocompleteUninstall bool
+	)
+
+	if app.AutocompleteInstallFlag == "" {
+		app.AutocompleteInstallFlag = defaultAutocompleteInstallFlag
+	}
+
+	if app.AutocompleteUninstallFlag == "" {
+		app.AutocompleteUninstallFlag = defaultAutocompleteUninstallFlag
+	}
+
+	if app.AutocompleteInstaller == nil {
+		app.AutocompleteInstaller = &autocompleteInstaller{}
+	}
+
+	for _, arg := range arguments {
+		switch {
+		// Check for autocomplete flags
+		case arg == "-"+app.AutocompleteInstallFlag || arg == "--"+app.AutocompleteInstallFlag:
+			isAutocompleteInstall = true
+
+		case arg == "-"+app.AutocompleteUninstallFlag || arg == "--"+app.AutocompleteUninstallFlag:
+			isAutocompleteUninstall = true
+		}
+	}
+
+	// Autocomplete requires the "Name" to be set so that we know what command to setup the autocomplete on.
+	if app.Name == "" {
+		return errors.Errorf("internal error: App.Name must be specified for autocomplete to work")
+	}
+
+	// If both install and uninstall flags are specified, then error
+	if isAutocompleteInstall && isAutocompleteUninstall {
+		return errors.Errorf("either the autocomplete install or uninstall flag may be specified, but not both")
+	}
+
+	// If the install flag is specified, perform the install or uninstall and exit
+	if isAutocompleteInstall {
+		err := app.AutocompleteInstaller.Install(app.Name)
+		return NewExitError(err, 0)
+	}
+
+	if isAutocompleteUninstall {
+		err := app.AutocompleteInstaller.Uninstall(app.Name)
+		return NewExitError(err, 0)
+	}
+
+	return nil
+}
+
 func (app *App) handleExitCoder(err error) error {
 	return handleExitCoder(err, app.OsExiter)
 }