fix: Print correct error, when non-root user run "rhc status"

* Card ID: CCT-288
* When "rhc status" is run as non-root user, then status about
  insighst-client should not tell that insights-client is not
  registered.
* When "rhc status" is run by non-root user, then rhc prints
  decent error about insights client. It prints: "Insights
  client must be run as root."
* Also fixed the case, when status command is run with
  "--format json". When some error happens, then generated
  JSON contains real error message and not empty dictionary.

insights.go

@@ -1,7 +1,11 @@
 package main
 
 import (
+	"bytes"
+	"errors"
+	"fmt"
 	"os/exec"
+	"strings"
 )
 
 func registerInsights() error {
@@ -17,15 +21,25 @@ func unregisterInsights() error {
 }
 
 func insightsIsRegistered() (bool, error) {
+	var errBuffer bytes.Buffer
 	cmd := exec.Command("/usr/bin/insights-client", "--status")
+	cmd.Stderr = &errBuffer
 
 	err := cmd.Run()
 
 	if err != nil {
 		// When the error is ExitError, then we know that insights-client only returned
 		// some error code not equal to zero. We do not care about error number.
-		if _, ok := err.(*exec.ExitError); ok {
-			return false, nil
+		var exitError *exec.ExitError
+		if errors.As(err, &exitError) {
+			// When stderr is not empty, then we should return this as error
+			// to be able to print this error in rhc output
+			stdErr := errBuffer.String()
+			if len(stdErr) == 0 {
+				return false, nil
+			} else {
+				return false, fmt.Errorf("%s", strings.TrimSpace(stdErr))
+			}
 		} else {
 			return false, err
 		}

main.go

@@ -497,13 +497,13 @@ func canonicalFactAction(_ *cli.Context) error {
 // like xml:"hostname"
 type SystemStatus struct {
 	SystemHostname    string `json:"hostname"`
-	HostnameError     error  `json:"hostname_error,omitempty"`
+	HostnameError     string `json:"hostname_error,omitempty"`
 	RHSMConnected     bool   `json:"rhsm_connected"`
-	RHSMError         error  `json:"rhsm_error,omitempty"`
+	RHSMError         string `json:"rhsm_error,omitempty"`
 	InsightsConnected bool   `json:"insights_connected"`
-	InsightsError     error  `json:"insights_error,omitempty"`
+	InsightsError     string `json:"insights_error,omitempty"`
 	YggdrasilRunning  bool   `json:"yggdrasil_running"`
-	YggdrasilError    error  `json:"yggdrasil_error,omitempty"`
+	YggdrasilError    string `json:"yggdrasil_error,omitempty"`
 }
 
 // printJSONStatus tries to print the system status as JSON to stdout.
@@ -577,7 +577,7 @@ func statusAction(ctx *cli.Context) (err error) {
 	hostname, err := os.Hostname()
 	if err != nil {
 		if uiSettings.isMachineReadable {
-			systemStatus.HostnameError = err
+			systemStatus.HostnameError = err.Error()
 		} else {
 			return cli.Exit(err, 1)
 		}

status.go

@@ -62,7 +62,7 @@ func insightStatus(systemStatus *SystemStatus) {
 		} else {
 			if uiSettings.isMachineReadable {
 				systemStatus.InsightsConnected = false
-				systemStatus.InsightsError = err
+				systemStatus.InsightsError = err.Error()
 			} else {
 				fmt.Printf(uiSettings.iconError+" Cannot execute insights-client: %v\n", err)
 			}
@@ -76,15 +76,15 @@ func serviceStatus(systemStatus *SystemStatus) error {
 	conn, err := systemd.NewSystemConnectionContext(ctx)
 	if err != nil {
 		systemStatus.YggdrasilRunning = false
-		systemStatus.YggdrasilError = err
+		systemStatus.YggdrasilError = err.Error()
 		return fmt.Errorf("unable to connect to systemd: %s", err)
 	}
 	defer conn.Close()
 	unitName := ServiceName + ".service"
 	properties, err := conn.GetUnitPropertiesContext(ctx, unitName)
 	if err != nil {
 		systemStatus.YggdrasilRunning = false
-		systemStatus.YggdrasilError = err
+		systemStatus.YggdrasilError = err.Error()
 		return fmt.Errorf("unable to get properties of %s: %s", unitName, err)
 	}
 	activeState := properties["ActiveState"]