management: Provide a way to deactivate the push registration.

docs/production/mobile-push-notifications.md

@@ -287,10 +287,50 @@ If you'd like to rotate your server's API key for this service
 generate a new `zulip_org_key` and store that new key in
 `/etc/zulip/zulip-secrets.conf`.
 
+## Deactivating your server's registration
+
+If you are deleting your Zulip server or otherwise no longer want to
+use the Mobile Push Notification Service, you can deactivate your server's
+registration.
+
+1. [Cancel any paid
+   plans](https://zulip.com/help/self-hosted-billing#cancel-paid-plan)
+   associated with your server.
+
+1. Run the deregistration command. If you installed Zulip directly on
+   the server (without Docker), run as root:
+
+   ```
+   su zulip -c '/home/zulip/deployments/current/manage.py register_server --deactivate'
+   ```
+
+   Or if you're using Docker, run:
+
+   ```
+   docker exec -it -u zulip <container_name> /home/zulip/deployments/current/manage.py register_server --deactivate
+   ```
+
+1. Comment out the
+   `PUSH_NOTIFICATION_BOUNCER_URL = 'https://push.zulipchat.com'` line
+   in your `/etc/zulip/settings.py` file (i.e., add `# ` at the
+   start of the line), and [restart your Zulip
+   server](settings.md#making-changes).
+
+If you ever need to reactivate your server's registration, [contact Zulip
+support](https://zulip.com/help/contact-support).
+
+### Pausing use of the Mobile Push Notification Service
+
+You can temporarily stop using the Mobile Push Notification Service. Comment out
+the `PUSH_NOTIFICATION_BOUNCER_URL = 'https://push.zulipchat.com'` line in your
+`/etc/zulip/settings.py` file (i.e., add `# ` at the start of the line), and
+[restart your Zulip server](settings.md#making-changes). This approach makes it
+easy to start using the service again by uncommenting the same line.
+
 ## Sending push notifications directly from your server
 
 This section documents an alternative way to send push notifications
-that does not involve using the Mobile Push Notifications Service at
+that does not involve using the Mobile Push Notification Service at
 the cost of needing to compile and distribute modified versions of the
 Zulip mobile apps.
 

zerver/management/commands/register_server.py

@@ -10,7 +10,11 @@ from requests.models import Response
 from typing_extensions import override
 
 from zerver.lib.management import ZulipBaseCommand, check_config
-from zerver.lib.remote_server import PushBouncerSession, send_server_data_to_push_bouncer
+from zerver.lib.remote_server import (
+    PushBouncerSession,
+    send_json_to_push_bouncer,
+    send_server_data_to_push_bouncer,
+)
 
 if settings.DEVELOPMENT:
     SECRETS_FILENAME = "zproject/dev-secrets.conf"
@@ -28,11 +32,17 @@ class Command(ZulipBaseCommand):
             action="store_true",
             help="Agree to the Zulipchat Terms of Service: https://zulip.com/policies/terms.",
         )
-        parser.add_argument(
+        action = parser.add_mutually_exclusive_group()
+        action.add_argument(
             "--rotate-key",
             action="store_true",
             help="Automatically rotate your server's zulip_org_key",
         )
+        action.add_argument(
+            "--deactivate",
+            action="store_true",
+            help="Deregister the server; this will stop mobile push notifications",
+        )
 
     @override
     def handle(self, *args: Any, **options: Any) -> None:
@@ -58,6 +68,11 @@ class Command(ZulipBaseCommand):
                     "in /etc/zulip/settings.py (remove the '#')"
                 )
 
+        if options["deactivate"]:
+            send_json_to_push_bouncer("POST", "server/deactivate", {})
+            print("Mobile Push Notification Service registration successfully deactivated!")
+            return
+
         request = {
             "zulip_org_id": settings.ZULIP_ORG_ID,
             "zulip_org_key": settings.ZULIP_ORG_KEY,