Clean up existing embedded cluster systemd service before creating symlink (#675)

* Clean up existing embedded cluster systemd service before creating symlink

* use lstat instead of stat

* lstat on reset too

* both 'worker' and 'controller' nodes will have 'worker' in the command, use 'enable-worker' instead

* add comment

---------

Co-authored-by: Andrew Lavery <laverya@umich.edu>

Author: sgalsaleh

cmd/embedded-cluster/install.go

@@ -79,20 +79,6 @@ func configureNetworkManager(c *cli.Context) error {
 	return nil
 }
 
-// runPostInstall is a helper function that run things just after the k0s install
-// command ran.
-func runPostInstall() error {
-	src := "/etc/systemd/system/k0scontroller.service"
-	dst := fmt.Sprintf("/etc/systemd/system/%s.service", defaults.BinaryName())
-	if err := os.Symlink(src, dst); err != nil {
-		return fmt.Errorf("failed to create symlink: %w", err)
-	}
-	if _, err := helpers.RunCommand("systemctl", "daemon-reload"); err != nil {
-		return fmt.Errorf("unable to get reload systemctl daemon: %w", err)
-	}
-	return installAndEnableLocalArtifactMirror()
-}
-
 // RunHostPreflights runs the host preflights we found embedded in the binary
 // on all configured hosts. We attempt to read HostPreflights from all the
 // embedded Helm Charts and from the Kots Application Release files.
@@ -505,9 +491,9 @@ var installCommand = &cli.Command{
 			metrics.ReportApplyFinished(c, err)
 			return err
 		}
-		logrus.Debugf("running post install")
-		if err := runPostInstall(); err != nil {
-			err := fmt.Errorf("unable to run post install: %w", err)
+		logrus.Debugf("creating systemd unit files")
+		if err := createSystemdUnitFiles(false); err != nil {
+			err := fmt.Errorf("unable to create systemd unit files: %w", err)
 			metrics.ReportApplyFinished(c, err)
 			return err
 		}

cmd/embedded-cluster/join.go

@@ -212,7 +212,9 @@ var joinCommand = &cli.Command{
 		}
 
 		logrus.Debugf("creating systemd unit files")
-		if err := createSystemdUnitFiles(jcmd.K0sJoinCommand); err != nil {
+		// both controller and worker nodes will have 'worker' in the join command, but only controllers will have 'enable-worker'
+		// https://github.com/replicatedhq/kots/blob/6a0602f4054d5d5f2d97e649b3303a059f0064d9/pkg/embeddedcluster/node_join.go#L183
+		if err := createSystemdUnitFiles(!strings.Contains(jcmd.K0sJoinCommand, "enable-worker")); err != nil {
 			err := fmt.Errorf("unable to create systemd unit files: %w", err)
 			metrics.ReportJoinFailed(c.Context, jcmd.MetricsBaseURL, jcmd.ClusterID, err)
 			return err
@@ -386,22 +388,22 @@ func systemdUnitFileName() string {
 
 // createSystemdUnitFiles links the k0s systemd unit file. this also creates a new
 // systemd unit file for the local artifact mirror service.
-func createSystemdUnitFiles(fullcmd string) error {
+func createSystemdUnitFiles(isWorker bool) error {
 	dst := systemdUnitFileName()
-	if _, err := os.Stat(dst); err == nil {
+	if _, err := os.Lstat(dst); err == nil {
 		if err := os.Remove(dst); err != nil {
 			return err
 		}
 	}
 	src := "/etc/systemd/system/k0scontroller.service"
-	if strings.Contains(fullcmd, "worker") {
+	if isWorker {
 		src = "/etc/systemd/system/k0sworker.service"
 	}
 	if err := os.Symlink(src, dst); err != nil {
-		return err
+		return fmt.Errorf("failed to create symlink: %w", err)
 	}
 	if _, err := helpers.RunCommand("systemctl", "daemon-reload"); err != nil {
-		return err
+		return fmt.Errorf("unable to get reload systemctl daemon: %w", err)
 	}
 	return installAndEnableLocalArtifactMirror()
 }

cmd/embedded-cluster/restore.go

@@ -762,9 +762,9 @@ var restoreCommand = &cli.Command{
 			if err := installK0s(); err != nil {
 				return fmt.Errorf("unable update cluster: %w", err)
 			}
-			logrus.Debugf("running post install")
-			if err := runPostInstall(); err != nil {
-				return fmt.Errorf("unable to run post install: %w", err)
+			logrus.Debugf("creating systemd unit files")
+			if err := createSystemdUnitFiles(false); err != nil {
+				return fmt.Errorf("unable to create systemd unit files: %w", err)
 			}
 			logrus.Debugf("waiting for k0s to be ready")
 			if err := waitForK0s(); err != nil {

cmd/embedded-cluster/uninstall.go

@@ -412,7 +412,7 @@ var resetCommand = &cli.Command{
 			}
 		}
 
-		if _, err := os.Stat(systemdUnitFileName()); err == nil {
+		if _, err := os.Lstat(systemdUnitFileName()); err == nil {
 			if err := os.Remove(systemdUnitFileName()); err != nil {
 				return fmt.Errorf("failed to remove systemd unit file: %w", err)
 			}