Extract privileged command wrapper into util

Without this, it makes the code a bit harder to read.

This fixes it by extracting the method.

Signed-off-by: Jean-Philippe Evrard <open-source@a.spamming.party>

pkg/util/util.go

@@ -1,6 +1,7 @@
 package util
 
 import (
+	"fmt"
 	"os/exec"
 
 	log "github.com/sirupsen/logrus"
@@ -21,3 +22,14 @@ func NewCommand(name string, arg ...string) *exec.Cmd {
 
 	return cmd
 }
+
+// PrivilegedHostCommand wraps the command with nsenter.
+// It allows to run a command from systemd's namespace for example (pid 1)
+// This relies on hostPID:true and privileged:true to enter host mount space
+// For info, rancher based need different pid, which should be user given.
+// until we have a better discovery mechanism.
+func PrivilegedHostCommand(pid int, command []string) []string {
+	cmd := []string{"/usr/bin/nsenter", fmt.Sprintf("-m/proc/%d/ns/mnt", pid), "--"}
+	cmd = append(cmd, command...)
+	return cmd
+}

pkg/util/util_test.go

@@ -0,0 +1,31 @@
+package util
+
+import (
+	"reflect"
+	"testing"
+)
+
+func Test_buildHostCommand(t *testing.T) {
+	type args struct {
+		pid     int
+		command []string
+	}
+	tests := []struct {
+		name string
+		args args
+		want []string
+	}{
+		{
+			name: "Ensure command will run with nsenter",
+			args: args{pid: 1, command: []string{"ls", "-Fal"}},
+			want: []string{"/usr/bin/nsenter", "-m/proc/1/ns/mnt", "--", "ls", "-Fal"},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := PrivilegedHostCommand(tt.args.pid, tt.args.command); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("buildHostCommand() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}