subproc: lazy lookup nomad binary in self call (#20231)

helper/subproc/self.go

@@ -8,14 +8,18 @@ import (
 	"os"
 	"os/exec"
 	"strings"
+	"sync"
 )
 
 var (
 	// executable is the executable of this process
 	executable string
+	once       sync.Once
 )
 
-func init() {
+// Self returns the path to the executable of this process.
+func Self() string {
+	once.Do(func() {
 		s, err := os.Executable()
 		if err != nil {
 			panic(fmt.Sprintf("failed to detect executable: %v", err))
@@ -29,9 +33,6 @@ func init() {
 			}
 		}
 		executable = s
-}
-
-// Self returns the path to the executable of this process.
-func Self() string {
+	})
 	return executable
 }

helper/subproc/self_test.go

@@ -0,0 +1,15 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: BUSL-1.1
+
+package subproc
+
+import (
+	"testing"
+
+	"github.com/shoenig/test/must"
+)
+
+func TestSelf(t *testing.T) {
+	value := Self()
+	must.NotEq(t, "", value)
+}