Warnings that k8s service may not work

src/k8s/cmd/k8s/k8s_bootstrap.go

@@ -45,7 +45,7 @@ func newBootstrapCmd(env cmdutil.ExecutionEnvironment) *cobra.Command {
 		Use:    "bootstrap",
 		Short:  "Bootstrap a new Kubernetes cluster",
 		Long:   "Generate certificates, configure service arguments and start the Kubernetes services.",
-		PreRun: chainPreRunHooks(hookRequireRoot(env), hookInitializeFormatter(env, &opts.outputFormat)),
+		PreRun: chainPreRunHooks(hookRequireRoot(env), hookInitializeFormatter(env, &opts.outputFormat), cmdutil.HookVerifyResources(false)),
 		Run: func(cmd *cobra.Command, args []string) {
 			if opts.interactive && opts.configFile != "" {
 				cmd.PrintErrln("Error: --interactive and --file flags cannot be set at the same time.")

src/k8s/cmd/k8s/k8s_join_cluster.go

@@ -32,7 +32,7 @@ func newJoinClusterCmd(env cmdutil.ExecutionEnvironment) *cobra.Command {
 	cmd := &cobra.Command{
 		Use:    "join-cluster <join-token>",
 		Short:  "Join a cluster using the provided token",
-		PreRun: chainPreRunHooks(hookRequireRoot(env), hookInitializeFormatter(env, &opts.outputFormat)),
+		PreRun: chainPreRunHooks(hookRequireRoot(env), hookInitializeFormatter(env, &opts.outputFormat), cmdutil.HookVerifyResources(false)),
 		Args:   cmdutil.ExactArgs(env, 1),
 		Run: func(cmd *cobra.Command, args []string) {
 			token := args[0]

src/k8s/cmd/k8sd/k8sd.go

@@ -33,8 +33,9 @@ func addCommands(root *cobra.Command, group *cobra.Group, commands ...*cobra.Com
 
 func NewRootCmd(env cmdutil.ExecutionEnvironment) *cobra.Command {
 	cmd := &cobra.Command{
-		Use:   "k8sd",
-		Short: "Canonical Kubernetes orchestrator and clustering daemon",
+		Use:    "k8sd",
+		Short:  "Canonical Kubernetes orchestrator and clustering daemon",
+		PreRun: cmdutil.HookVerifyResources(true),
 		Run: func(cmd *cobra.Command, args []string) {
 			// configure logging
 			log.Configure(log.Options{

src/k8s/cmd/util/hooks.go

@@ -0,0 +1,102 @@
+package cmdutil
+
+import (
+	"fmt"
+	"os"
+	"strings"
+	"syscall"
+
+	"github.com/spf13/cobra"
+)
+
+const initialProcesEnvironmentVariables = "/proc/1/environ"
+
+// paths to validate if root in the owner
+var pathsOwnershipCheck = []string{"/sys", "/proc", "/dev/kmsg"}
+
+// HookVerifyResources checks ownership of dirs required for k8s to run.
+// HookVerifyResources if verbose true prints out list of potenital issues.
+// If potential issue found pops up warning for user.
+func HookVerifyResources(verbose bool) func(*cobra.Command, []string) {
+	return func(cmd *cobra.Command, args []string) {
+		errMsgs := VerifyPaths()
+
+		// printing report
+		if len(errMsgs) > 0 {
+			if verbose {
+				cmd.PrintErrln("Warning: When validating required resources potential issues found:")
+				for _, errMsg := range errMsgs {
+					cmd.PrintErrln("\t", errMsg)
+				}
+			}
+			if lxd, err := validateLXD(); lxd {
+				cmd.PrintErrln("The lxc profile for MicroK8s might be missing.")
+				cmd.PrintErrln("For running k8s inside LXD container refer to " +
+					"https://documentation.ubuntu.com/canonical-kubernetes/latest/snap/howto/install/lxd/")
+			} else if err != nil {
+				cmd.PrintErrf(err.Error())
+
+			}
+		}
+	}
+}
+
+func VerifyPaths() []string {
+	var errMsg []string
+	// check ownership of required dirs
+	for _, pathToCheck := range pathsOwnershipCheck {
+		if err := validateRootOwnership(pathToCheck); err != nil {
+			errMsg = append(errMsg, err.Error())
+		}
+	}
+	return errMsg
+}
+
+func getOwnership(path string) (int, int, error) {
+	info, err := os.Stat(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return 0, 0, fmt.Errorf("%s do not exist", path)
+		} else {
+			return 0, 0, err
+		}
+	}
+	if stat, ok := info.Sys().(*syscall.Stat_t); ok {
+		return int(stat.Uid), int(stat.Gid), nil
+	} else {
+		return 0, 0, fmt.Errorf("cannot access %s", path)
+	}
+}
+
+// validateRootOwnership checks if given path owner root and root group.
+func validateRootOwnership(path string) error {
+	UID, GID, err := getOwnership(path)
+	if err != nil {
+		return err
+	}
+	if UID != 0 {
+		return fmt.Errorf("owner of %s is user with UID %d expected 0", path, UID)
+	}
+	if GID != 0 {
+		return fmt.Errorf("owner of %s is group with GID %d expected 0", path, GID)
+	}
+	return nil
+}
+
+// validateLXD checks if k8s runs in lxd container if so returns link to documentation
+func validateLXD() (bool, error) {
+	dat, err := os.ReadFile(initialProcesEnvironmentVariables)
+	if err != nil {
+		// if permission to file is missing we still want to display info about lxd
+		if os.IsPermission(err) {
+			return true, err
+		}
+		return false, err
+	}
+	env := string(dat)
+	if strings.Contains(env, "container=lxc") {
+
+		return true, nil
+	}
+	return false, nil
+}