ref(*): use listSystemdUnits as systemd check

Signed-off-by: Vaughn Dice <[email protected]>

Author: vdice

images/installer/Dockerfile

@@ -11,7 +11,7 @@ RUN CGO_ENABLED=0 go build -o rcm-node-installer ./cmd/node-installer
 RUN /app/rcm-node-installer -h
 
 # Using busybox instead of scratch so that the nsenter utility is present, as used in restarter logic
-FROM busybox
+FROM busybox:1.37
 COPY --from=builder /app/rcm-node-installer /rcm-node-installer
 
 ENTRYPOINT ["/rcm-node-installer"]

internal/containerd/restart_unix.go

@@ -39,8 +39,8 @@ func NewDefaultRestarter() Restarter {
 }
 
 func (c defaultRestarter) Restart() error {
-	// If systemctl exists, use that, otherwise go pid
-	if UsesSystemd() {
+	// If listing systemd units succeeds, prefer systemctl restart; otherwise kill pid
+	if _, err := listSystemdUnits(); err == nil {
 		out, err := nsenterCmd("systemctl", "restart", "containerd").CombinedOutput()
 		slog.Debug(string(out))
 		if err != nil {
@@ -67,7 +67,7 @@ type K0sRestarter struct{}
 func (c K0sRestarter) Restart() error {
 	// First, collect systemd units to determine which mode k0s is running in, eg
 	// k0sworker or k0scontroller
-	units, err := nsenterCmd("systemctl", "list-units").CombinedOutput()
+	units, err := listSystemdUnits()
 	if err != nil {
 		return fmt.Errorf("unable to list systemd units: %w", err)
 	}
@@ -85,9 +85,10 @@ func (c K0sRestarter) Restart() error {
 type K3sRestarter struct{}
 
 func (c K3sRestarter) Restart() error {
-	// This restarter will be used both for stock K3s distros
-	// using systemd as well as K3d, which does not.
-	if UsesSystemd() {
+	// This restarter will be used both for stock K3s distros, which use systemd as well as K3d, which does not.
+
+	// If listing systemd units succeeds, prefer systemctl restart; otherwise kill pid
+	if _, err := listSystemdUnits(); err == nil {
 		out, err := nsenterCmd("systemctl", "restart", "k3s").CombinedOutput()
 		slog.Debug(string(out))
 		if err != nil {
@@ -129,7 +130,7 @@ type RKE2Restarter struct{}
 func (c RKE2Restarter) Restart() error {
 	// First, collect systemd units to determine which mode rke2 is running in, eg
 	// rke2-agent or rke2-server
-	units, err := nsenterCmd("systemctl", "list-units").CombinedOutput()
+	units, err := listSystemdUnits()
 	if err != nil {
 		return fmt.Errorf("unable to list systemd units: %w", err)
 	}
@@ -144,16 +145,8 @@ func (c RKE2Restarter) Restart() error {
 	return nil
 }
 
-// TODO: lifted and amended from https://github.com/spinframework/runtime-class-manager/pull/387
-//
-// UsesSystemd checks if the system is using systemd
-func UsesSystemd() bool {
-	cmd := nsenterCmd("systemctl", "list-units", "|", "grep", "-q", "containerd.service")
-	if err := cmd.Run(); err != nil {
-		slog.Debug("Error with systemctl: \n", "error", err)
-		return false
-	}
-	return true
+func listSystemdUnits() ([]byte, error) {
+	return nsenterCmd("systemctl", "list-units", "--type", "service").CombinedOutput()
 }
 
 func nsenterCmd(cmd ...string) *exec.Cmd {