Fix Fleet Desktop opening of URL on Ubuntu 21/22 (#6314)

* Fix Fleet Desktop opening URL on Ubuntu 21/22

* Fine tunning: fix for Ubuntu 18

orbit/pkg/execuser/execuser_linux.go

@@ -24,10 +24,13 @@ func run(path string, opts eopts) error {
 		Int64("id", user.id).
 		Msg("running sudo")
 
-	arg := []string{"-u", user.name, "-H"}
+	// Flag `-i` is needed to run the command with the user's context, from `man sudo`:
+	// "The command is run with an environment similar to the one a user would receive at log in"
+	arg := []string{"-i", "-u", user.name, "-H"}
 	for _, nv := range opts.env {
 		arg = append(arg, fmt.Sprintf("%s=%s", nv[0], nv[1]))
 	}
+
 	arg = append(arg,
 		// TODO(lucas): Default to display 0, revisit when working on
 		// multi-user/multi-session support. This assumes there's only
@@ -36,7 +39,11 @@ func run(path string, opts eopts) error {
 		// DBUS_SESSION_BUS_ADDRESS sets the location of the user login session bus.
 		// Required by the libayatana-appindicator3 library to display a tray icon
 		// on the desktop session.
+		//
+		// This is required for Ubuntu 18, and not required for Ubuntu 21/22
+		// (because it's already part of the user).
 		fmt.Sprintf("DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/%d/bus", user.id),
+		// Append the packaged libayatana-appindicator3 libraries path to LD_LIBRARY_PATH.
 		fmt.Sprintf("LD_LIBRARY_PATH=%s:%s", filepath.Dir(path), os.ExpandEnv("$LD_LIBRARY_PATH")),
 		path,
 	)

orbit/pkg/packaging/linux_shared.go

@@ -307,10 +307,15 @@ func writePreRemove(opt Options, path string) error {
 	// We add `|| true` in case the service is not running
 	// or has been manually disabled already. Otherwise,
 	// uninstallation fails.
+	//
+	// "pkill fleet-desktop" is required because the application
+	// runs as user (separate from sudo command that launched it),
+	// so on some systems it's not killed properly.
 	if err := ioutil.WriteFile(path, []byte(`#!/bin/sh
 
 systemctl stop orbit.service || true
 systemctl disable orbit.service || true
+pkill fleet-desktop || true
 `), constant.DefaultFileMode); err != nil {
 		return fmt.Errorf("write file: %w", err)
 	}