handle new pyngrok connect output

Author: RussTedrake

setup.py

@@ -23,7 +23,7 @@
       "numpy >= 1.14.0" if sys.version_info >= (3, 0) else "numpy >= 1.14.0, < 1.17",
       "tornado >= 4.0.0" if sys.version_info >= (3, 0) else "tornado >= 4.0.0, < 6.0",
       "pyzmq >= 17.0.0",
-      "pyngrok >= 4.1.6"
+      "pyngrok >= 4.1.6" if sys.version_info >= (3, 0) else "pyngrok >= 4.1.6, < 5.0.0"
     ],
     zip_safe=False,
     include_package_data=True

src/meshcat/servers/zmqserver.py

@@ -218,9 +218,16 @@ def f(port):
                 if sys.version_info.major >= 3:
                         kwargs['start_new_session'] = True
                 config = pyngrok.conf.PyngrokConfig(**kwargs)
-                self.web_url = pyngrok.ngrok.connect(self.fileserver_port, "http", pyngrok_config=config) + "/static/"
-                print("\n")  # ensure any pyngrok output is properly terminated.
+                self.web_url = pyngrok.ngrok.connect(self.fileserver_port, "http", pyngrok_config=config)
+
+                # pyngrok >= 5.0.0 returns an NgrokTunnel object instead of the string.
+                if sys.version_info.major < 3:
+                    self.web_url = self.web_url.decode("utf-8")
+                elif not isinstance(self.web_url, str):
+                    self.web_url = self.web_url.public_url
+                self.web_url += "/static/"
 
+                print("\n")  # ensure any pyngrok output is properly terminated.
                 def cleanup():
                     pyngrok.ngrok.kill()