Initialize steppath using a function instead of init

This commit changes the initialization of the STEPPATH to an Init
function instead of doing it at the start using Go's init function.

It also removes the mkdir of STEPPATH. If necessary, commands like
"step ca bootstrap" or "step ca init" will create the directory.

Author: maraino

go.mod

@@ -31,5 +31,3 @@ require (
 	gopkg.in/square/go-jose.v2 v2.6.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
-
-//replace go.step.sm/crypto => ../crypto

step/config.go

@@ -2,12 +2,12 @@ package step
 
 import (
 	"fmt"
-	"log"
 	"os"
 	"os/user"
 	"path/filepath"
 	"runtime"
 	"strings"
+	"sync"
 	"time"
 )
 
@@ -24,55 +24,65 @@ var (
 	name      = "Smallstep CLI"
 	buildTime = "N/A"
 	version   = "N/A"
+)
 
-	// stepBasePath will be populated in init() with the proper STEPPATH.
-	stepBasePath string
+var cache struct {
+	sync.Once
+	err          error
+	stepBasePath string // stepBasePath will be populated in init() with the proper STEPPATH.
+	homePath     string // homePath will be populated in init() with the proper HOME.
+}
 
-	// homePath will be populated in init() with the proper HOME.
-	homePath string
-)
+// Init initializes the step environment.
+//
+// A program calling this function should fail because the step variables would
+// be undefined.
+func Init() error {
+	if err := initStepPath(); err != nil {
+		return err
+	}
+	return Contexts().Init()
+}
+
+func initStepPath() error {
+	cache.Do(func() {
+		// Get home path from environment or from the user object.
+		homePath := os.Getenv(HomeEnv)
+		if homePath == "" {
+			usr, err := user.Current()
+			if err == nil && usr.HomeDir != "" {
+				homePath = usr.HomeDir
+			} else {
+				cache.err = fmt.Errorf("error obtaining home directory, please define environment variable %s", HomeEnv)
+				return
+			}
+		}
 
-func init() {
-	l := log.New(os.Stderr, "", 0)
-
-	// Get home path from environment or from the user object.
-	homePath = os.Getenv(HomeEnv)
-	if homePath == "" {
-		usr, err := user.Current()
-		if err == nil && usr.HomeDir != "" {
-			homePath = usr.HomeDir
-		} else {
-			l.Fatalf("Error obtaining home directory, please define environment variable %s.", HomeEnv)
+		// Get step path from environment or relative to home.
+		stepBasePath := os.Getenv(PathEnv)
+		if stepBasePath == "" {
+			stepBasePath = filepath.Join(homePath, ".step")
 		}
-	}
 
-	// Get step path from environment or relative to home.
-	stepBasePath = os.Getenv(PathEnv)
-	if stepBasePath == "" {
-		stepBasePath = filepath.Join(homePath, ".step")
-	}
+		// cleanup and add paths to cache
+		cache.homePath = filepath.Clean(homePath)
+		cache.stepBasePath = filepath.Clean(stepBasePath)
+	})
 
-	// cleanup
-	homePath = filepath.Clean(homePath)
-	stepBasePath = filepath.Clean(stepBasePath)
-
-	// Check for presence or attempt to create it if necessary.
-	//
-	// Some environments (e.g. third party docker images) might fail creating
-	// the directory, so this should not panic if it can't.
-	if fi, err := os.Stat(stepBasePath); err != nil {
-		os.MkdirAll(stepBasePath, 0700)
-	} else if !fi.IsDir() {
-		l.Fatalf("File '%s' is not a directory.", stepBasePath)
-	}
+	return cache.err
+}
 
-	// Initialize context state.
-	Contexts().Init()
+// Home returns the user home directory using the environment variable HOME or
+// the os/user package.
+func Home() string {
+	_ = initStepPath()
+	return cache.homePath
 }
 
 // BasePath returns the base path for the step configuration directory.
 func BasePath() string {
-	return stepBasePath
+	_ = initStepPath()
+	return cache.stepBasePath
 }
 
 // Path returns the path for the step configuration directory.
@@ -153,12 +163,6 @@ func CurrentContextFile() string {
 	return filepath.Join(BasePath(), "current-context.json")
 }
 
-// Home returns the user home directory using the environment variable HOME or
-// the os/user package.
-func Home() string {
-	return homePath
-}
-
 // Abs returns the given path relative to the STEPPATH if it's not an
 // absolute path, relative to the home directory using the special string "~/",
 // or relative to the working directory using "./"
@@ -176,7 +180,7 @@ func Abs(path string) string {
 	slashed := filepath.ToSlash(path)
 	switch {
 	case strings.HasPrefix(slashed, "~/"):
-		return filepath.Join(homePath, path[2:])
+		return filepath.Join(Home(), path[2:])
 	case strings.HasPrefix(slashed, "./"), strings.HasPrefix(slashed, "../"):
 		if abs, err := filepath.Abs(path); err == nil {
 			return abs