cmd/operator-sdk/internal: explicitly set GOROOT (#2754)

* cmd/operator-sdk/internal: explicitly set GOROOT

If the user's GOROOT does not match the GOROOT used to build the
binary, they would be required to explicitly set the GOROOT env
variable to their go env GOROOT. To avoid this step for end-users
we can explicitly pull the GOROOT from go env and explicitly set
the GOROOT env variable.

Fixes: #2744

Author: aharbis

cmd/operator-sdk/internal/genutil/k8s.go

@@ -17,6 +17,7 @@ package genutil
 import (
 	"fmt"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"strings"
 
@@ -34,6 +35,16 @@ import (
 func K8sCodegen() error {
 	projutil.MustInProjectRoot()
 
+	goEnv, err := exec.Command("go", "env", "GOROOT").CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("failed to get GOROOT from go env: %w", err)
+	}
+	goRoot := strings.TrimSuffix(string(goEnv), "\n")
+	log.Debugf("Setting GOROOT=%s", goRoot)
+	if err := os.Setenv("GOROOT", goRoot); err != nil {
+		return fmt.Errorf("failed to set env GOROOT=%s: %w", goRoot, err)
+	}
+
 	repoPkg := projutil.GetGoPkg()
 
 	gvMap, err := k8sutil.ParseGroupSubpackages(scaffold.ApisDir)