Implement kubeadm reset

pkg/util/initsystem/initsystem.go

@@ -17,11 +17,18 @@ limitations under the License.
 package initsystem
 
 import (
+	"fmt"
 	"os/exec"
 	"strings"
 )
 
 type InitSystem interface {
+	// ServiceStart tries to start a specific service
+	ServiceStart(service string) error
+
+	// ServiceStop tries to stop a specific service
+	ServiceStop(service string) error
+
 	// ServiceExists ensures the service is defined for this init system.
 	ServiceExists(service string) bool
 
@@ -34,6 +41,18 @@ type InitSystem interface {
 
 type SystemdInitSystem struct{}
 
+func (sysd SystemdInitSystem) ServiceStart(service string) error {
+	args := []string{"start", service}
+	_, err := exec.Command("systemctl", args...).Output()
+	return err
+}
+
+func (sysd SystemdInitSystem) ServiceStop(service string) error {
+	args := []string{"stop", service}
+	_, err := exec.Command("systemctl", args...).Output()
+	return err
+}
+
 func (sysd SystemdInitSystem) ServiceExists(service string) bool {
 	args := []string{"status", service}
 	outBytes, _ := exec.Command("systemctl", args...).Output()
@@ -70,11 +89,11 @@ func (sysd SystemdInitSystem) ServiceIsActive(service string) bool {
 // getInitSystem returns an InitSystem for the current system, or nil
 // if we cannot detect a supported init system for pre-flight checks.
 // This indicates we will skip init system checks, not an error.
-func GetInitSystem() InitSystem {
+func GetInitSystem() (InitSystem, error) {
 	// Assume existence of systemctl in path implies this is a systemd system:
 	_, err := exec.LookPath("systemctl")
 	if err == nil {
-		return &SystemdInitSystem{}
+		return &SystemdInitSystem{}, nil
 	}
-	return nil
+	return nil, fmt.Errorf("no supported init system detected, skipping checking for services")
 }