django: Add custom runserver wrapper to limit startup logging.

This helps considerably in avoiding the `run-dev.py` startup output
confusing developers.

tools/linter_lib/exclude.py

@@ -6,6 +6,7 @@ EXCLUDED_FILES = [
     "puppet/zulip/files/nagios_plugins/zulip_nagios_server/check_website_response.sh",
     "scripts/lib/third",
     "static/third",
+    "zilencer/management/commands/rundjangoserver.py",
     # Transifex syncs translation.json files without trailing
     # newlines; there's nothing other than trailing newlines we'd be
     # checking for in these anyway.

tools/run-dev.py

@@ -133,7 +133,7 @@ with open(pid_file_path, 'w+') as f:
 
 def server_processes() -> List[List[str]]:
     main_cmds = [
-        ['./manage.py', 'runserver',
+        ['./manage.py', 'rundjangoserver',
          *manage_args, *runserver_args, f'127.0.0.1:{django_port}'],
         ['env', 'PYTHONUNBUFFERED=1', './manage.py', 'runtornado',
          *manage_args, f'127.0.0.1:{tornado_port}'],

zilencer/management/commands/rundjangoserver.py

@@ -0,0 +1,64 @@
+import errno
+import os
+import socket
+import sys
+from typing import Any, NoReturn
+
+from django.conf import settings
+from django.core.management.commands.runserver import Command as DjangoCommand
+from django.core.servers.basehttp import run
+from django.utils import autoreload
+
+
+class Command(DjangoCommand):
+    # Copied from Django's runserver and modified to remove print statements.
+    # This lets us declutter run-dev.py startup output.
+    def inner_run(self, *args: Any, **options: Any) -> None:
+        # If an exception was silenced in ManagementUtility.execute in order
+        # to be raised in the child process, raise it now.
+        autoreload.raise_last_exception()
+
+        threading = options['use_threading']
+        # 'shutdown_message' is a stealth option.
+        shutdown_message = options.get('shutdown_message', '')
+        quit_command = 'CTRL-BREAK' if sys.platform == 'win32' else 'CONTROL-C'
+
+        self.check(display_num_errors=False)
+        # Need to check migrations here, so can't use the
+        # requires_migrations_check attribute.
+        self.check_migrations()
+        self.stdout.write((
+            "Django process (re)started. Quit the server with %(quit_command)s.\n"
+        ) % {
+            "version": self.get_version(),
+            "settings": settings.SETTINGS_MODULE,
+            "protocol": self.protocol,
+            "addr": '[%s]' % self.addr if self._raw_ipv6 else self.addr,
+            "port": self.port,
+            "quit_command": quit_command,
+        })
+
+        try:
+            handler = self.get_handler(*args, **options)
+            run(self.addr, int(self.port), handler,
+                ipv6=self.use_ipv6, threading=threading, server_cls=self.server_cls)
+        except socket.error as e:
+            # Use helpful error messages instead of ugly tracebacks.
+            ERRORS = {
+                errno.EACCES: "You don't have permission to access that port.",
+                errno.EADDRINUSE: "That port is already in use.",
+                errno.EADDRNOTAVAIL: "That IP address can't be assigned to.",
+            }
+            try:
+                error_text = ERRORS[e.errno]
+            except KeyError:
+                error_text = str(e)
+            self.stderr.write("Error: %s" % error_text)
+            # Need to use an OS exit because sys.exit doesn't work in a thread
+            os._exit(1)
+        except KeyboardInterrupt:
+            if shutdown_message:
+                self.stdout.write(shutdown_message)
+            sys.exit(0)
+
+