feat: add cmdutil package to provide utils for commands (#970)

## Summary

1. add cmdutil package
2. move command related functions to this package
3. tweak some error handling

## How was it tested?

Author: hezhizhen

internal/boxcli/root.go

@@ -11,6 +11,7 @@ import (
 	"strings"
 
 	"github.com/spf13/cobra"
+
 	"go.jetpack.io/devbox/internal/boxcli/midcobra"
 	"go.jetpack.io/devbox/internal/cloud/openssh/sshshim"
 	"go.jetpack.io/devbox/internal/debug"
@@ -19,8 +20,8 @@ import (
 )
 
 var (
-	debugMiddleware *midcobra.DebugMiddleware = &midcobra.DebugMiddleware{}
-	traceMiddleware *midcobra.TraceMiddleware = &midcobra.TraceMiddleware{}
+	debugMiddleware = &midcobra.DebugMiddleware{}
+	traceMiddleware = &midcobra.TraceMiddleware{}
 )
 
 type rootCmdFlags struct {

internal/cmdutil/cmdutil.go

@@ -0,0 +1,25 @@
+// Copyright 2023 Jetpack Technologies Inc and contributors. All rights reserved.
+// Use of this source code is governed by the license in the LICENSE file.
+
+package cmdutil
+
+import (
+	"os/exec"
+)
+
+// Exists indicates if the command exists
+func Exists(command string) bool {
+	_, err := exec.LookPath(command)
+	return err == nil
+}
+
+// GetPathOrDefault gets the path for the given command.
+// If it's not found, it will return the given value instead.
+func GetPathOrDefault(command string, def string) string {
+	path, err := exec.LookPath(command)
+	if err != nil {
+		path = def
+	}
+
+	return path
+}

internal/impl/devbox.go

@@ -26,6 +26,7 @@ import (
 	"go.jetpack.io/devbox/internal/boxcli/featureflag"
 	"go.jetpack.io/devbox/internal/boxcli/generate"
 	"go.jetpack.io/devbox/internal/boxcli/usererr"
+	"go.jetpack.io/devbox/internal/cmdutil"
 	"go.jetpack.io/devbox/internal/conf"
 	"go.jetpack.io/devbox/internal/cuecfg"
 	"go.jetpack.io/devbox/internal/debug"
@@ -383,7 +384,7 @@ func (d *Devbox) GenerateEnvrc(force bool, source string) error {
 		)
 	}
 	// confirm .envrc doesn't exist and don't overwrite an existing .envrc
-	if commandExists("direnv") {
+	if cmdutil.Exists("direnv") {
 		// prompt for direnv allow
 		var result string
 		isInteractiveMode := isatty.IsTerminal(os.Stdin.Fd())
@@ -815,22 +816,26 @@ var nixEnvCache map[string]string
 // Note that this is in-memory cache of the final environment, and not the same
 // as the nix print-dev-env cache which is stored in a file.
 func (d *Devbox) nixEnv(ctx context.Context) (map[string]string, error) {
-	var err error
-	if nixEnvCache == nil {
-		usePrintDevEnvCache := false
-
-		// If lockfile is up-to-date, we can use the print-dev-env cache.
-		if lock, err := lock.Local(d); err != nil {
-			return nil, err
-		} else if upToDate, err := lock.IsUpToDate(); err != nil {
-			return nil, err
-		} else if upToDate {
-			usePrintDevEnvCache = true
-		}
+	if nixEnvCache != nil {
+		return nixEnvCache, nil
+	}
 
-		nixEnvCache, err = d.computeNixEnv(ctx, usePrintDevEnvCache)
+	usePrintDevEnvCache := false
+
+	// If lockfile is up-to-date, we can use the print-dev-env cache.
+	lockFile, err := lock.Local(d)
+	if err != nil {
+		return nil, err
 	}
-	return nixEnvCache, err
+	upToDate, err := lockFile.IsUpToDate()
+	if err != nil {
+		return nil, err
+	}
+	if upToDate {
+		usePrintDevEnvCache = true
+	}
+
+	return d.computeNixEnv(ctx, usePrintDevEnvCache)
 }
 
 func (d *Devbox) ogPathKey() string {
@@ -947,11 +952,6 @@ func (d *Devbox) configEnvs(computedEnv map[string]string) map[string]string {
 	return conf.OSExpandEnvMap(d.cfg.Env, computedEnv, d.ProjectDir())
 }
 
-func commandExists(command string) bool { // TODO: move to a utility package
-	_, err := exec.LookPath(command)
-	return err == nil
-}
-
 // ignoreCurrentEnvVar contains environment variables that Devbox should remove
 // from the slice of [os.Environ] variables before sourcing them. These are
 // variables that are set automatically by a new shell.
@@ -1042,7 +1042,6 @@ func addHashToEnv(env map[string]string) error {
 	hash, err := cuecfg.Hash(env)
 	if err == nil {
 		env[devboxShellEnvHashVarName] = hash
-
 	}
 	return err
 }

internal/impl/global.go

@@ -38,16 +38,17 @@ func (d *Devbox) AddGlobal(pkgs ...string) error {
 		found, err := nix.PkgExists(pkg, d.lockfile)
 		if err != nil {
 			return err
-		} else if !found {
+		}
+		if !found {
 			return nix.ErrPackageNotFound
 		}
 	}
-	var added []string
 	profilePath, err := GlobalNixProfilePath()
 	if err != nil {
 		return err
 	}
 
+	var added []string
 	total := len(pkgs)
 	for idx, pkg := range pkgs {
 		stepNum := idx + 1

internal/nix/doc.go

@@ -1,7 +1,7 @@
 // Copyright 2023 Jetpack Technologies Inc and contributors. All rights reserved.
 // Use of this source code is governed by the license in the LICENSE file.
 
-// Go API for nix.
+// Package nix provides Go API for nix.
 // Internally this is a wrapper around the nix command line utilities.
 // I'd love to use a go SDK instead, and drop the dependency on the CLI.
 // The dependency means that users need to install nix, before using devbox.

internal/nix/install.go

@@ -18,6 +18,7 @@ import (
 
 	"go.jetpack.io/devbox/internal/boxcli/usererr"
 	"go.jetpack.io/devbox/internal/build"
+	"go.jetpack.io/devbox/internal/cmdutil"
 	"go.jetpack.io/devbox/internal/fileutil"
 )
 
@@ -82,8 +83,7 @@ func Install(writer io.Writer, daemon *bool) error {
 }
 
 func BinaryInstalled() bool {
-	_, err := exec.LookPath("nix")
-	return err == nil
+	return cmdutil.Exists("nix")
 }
 
 func dirExists() bool {

internal/nix/run.go

@@ -10,6 +10,7 @@ import (
 	"os/exec"
 
 	"go.jetpack.io/devbox/internal/boxcli/usererr"
+	"go.jetpack.io/devbox/internal/cmdutil"
 	"go.jetpack.io/devbox/internal/debug"
 )
 
@@ -24,10 +25,7 @@ func RunScript(projectDir string, cmdWithArgs string, env map[string]string) err
 	}
 
 	// Try to find sh in the PATH, if not, default to a well known absolute path.
-	shPath, err := exec.LookPath("sh")
-	if err != nil {
-		shPath = "/bin/sh"
-	}
+	shPath := cmdutil.GetPathOrDefault("sh", "/bin/sh")
 	cmd := exec.Command(shPath, "-c", cmdWithArgs)
 	cmd.Env = envPairs
 	cmd.Dir = projectDir

internal/services/manager.go

@@ -109,7 +109,7 @@ func openGlobalConfigFile() (*os.File, error) {
 
 	err = lockFile(globalConfigFile)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("failed to lock file: %w", err)
 	}
 
 	return globalConfigFile, nil
@@ -204,11 +204,11 @@ func runProcessManagerInForeground(cmd *exec.Cmd, config *globalProcessComposeCo
 	config.File.Close()
 
 	err = cmd.Wait()
-
-	if err != nil && err.Error() == "exit status 1" {
-		fmt.Fprintf(w, "Process-compose was terminated remotely, %s\n", err.Error())
-		return nil
-	} else if err != nil {
+	if err != nil {
+		if err.Error() == "exit status 1" {
+			fmt.Fprintf(w, "Process-compose was terminated remotely, %s\n", err.Error())
+			return nil
+		}
 		return err
 	}
 
@@ -246,7 +246,7 @@ func runProcessManagerInBackground(cmd *exec.Cmd, config *globalProcessComposeCo
 
 	err = writeGlobalProcessComposeJSON(config, config.File)
 	if err != nil {
-		return fmt.Errorf("failed to write global process-compose config")
+		return fmt.Errorf("failed to write global process-compose config: %w", err)
 	}
 
 	return nil

internal/vercheck/vercheck.go

@@ -15,11 +15,12 @@ import (
 
 	"github.com/fatih/color"
 	"github.com/pkg/errors"
-	"go.jetpack.io/devbox/internal/build"
-	"go.jetpack.io/devbox/internal/ux"
 	"golang.org/x/mod/semver"
 
 	"go.jetpack.io/devbox/internal/boxcli/usererr"
+	"go.jetpack.io/devbox/internal/build"
+	"go.jetpack.io/devbox/internal/cmdutil"
+	"go.jetpack.io/devbox/internal/ux"
 	"go.jetpack.io/devbox/internal/xdg"
 )
 
@@ -75,9 +76,9 @@ func SelfUpdate(stdOut, stdErr io.Writer) error {
 
 func selfUpdateLauncher(stdOut, stdErr io.Writer) error {
 	installScript := ""
-	if _, err := exec.LookPath("curl"); err == nil {
+	if cmdutil.Exists("curl") {
 		installScript = "curl -fsSL https://get.jetpack.io/devbox | bash"
-	} else if _, err := exec.LookPath("wget"); err == nil {
+	} else if cmdutil.Exists("wget") {
 		installScript = "wget -qO- https://get.jetpack.io/devbox | bash"
 	} else {
 		return usererr.New("curl or wget is required to update devbox. Please install either and try again.")

internal/wrapnix/wrapper.go

@@ -9,12 +9,12 @@ import (
 	_ "embed"
 	"io/fs"
 	"os"
-	"os/exec"
 	"path/filepath"
 	"text/template"
 
 	"github.com/pkg/errors"
 
+	"go.jetpack.io/devbox/internal/cmdutil"
 	"go.jetpack.io/devbox/internal/nix"
 	"go.jetpack.io/devbox/internal/plugin"
 	"go.jetpack.io/devbox/internal/services"
@@ -43,18 +43,14 @@ func CreateWrappers(ctx context.Context, devbox devboxer) error {
 		return err
 	}
 
-	bashPath, err := exec.LookPath("bash")
-	if err != nil {
-		bashPath = "/bin/bash"
-	}
-
 	// Remove all old wrappers
 	_ = os.RemoveAll(filepath.Join(devbox.ProjectDir(), plugin.WrapperPath))
 
 	// Recreate the bin wrapper directory
 	destPath := filepath.Join(devbox.ProjectDir(), plugin.WrapperBinPath)
 	_ = os.MkdirAll(destPath, 0755)
 
+	bashPath := cmdutil.GetPathOrDefault("bash", "/bin/bash")
 	for _, service := range services {
 		if err = createWrapper(&createWrapperArgs{
 			BashPath:     bashPath,