mirror of https://github.com/zulip/zulip.git
251 lines
11 KiB
Markdown
251 lines
11 KiB
Markdown
# Mobile push notification service
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Zulip's iOS and Android mobile apps support receiving push
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notifications from Zulip servers to let users know when new messages
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have arrived. This is an important feature to having a great
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experience using the Zulip mobile apps.
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For technical reasons (explained below), in order to deliver mobile
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push notifications in the app store versions of our mobile apps, you
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will need to register your Zulip server with the Zulip mobile push
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notification service. This service will forward push notifications
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generated by your server to the Zulip mobile app automatically.
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## How to sign up
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Starting with Zulip 1.6 for both Android and iOS, Zulip servers
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support forwarding push notifications to a central push notification
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forwarding service. Accessing this service requires outgoing HTTPS
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access to the public Internet; if that is restricted by a proxy, you
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will need to [configure Zulip to use your outgoing HTTP
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proxy](../production/deployment.html#customizing-the-outgoing-http-proxy)
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first.
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You can enable this for your Zulip server as follows:
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1. Uncomment the
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`PUSH_NOTIFICATION_BOUNCER_URL = 'https://push.zulipchat.com'` line
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in your `/etc/zulip/settings.py` file (i.e. remove the `#` at the
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start of the line), and [restart your Zulip
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server](../production/settings.html#making-changes). If you
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installed your Zulip server with a version older than 1.6, you'll
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need to add the line (it won't be there to uncomment).
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1. If you're running Zulip 1.8.1 or newer, you can run the
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registration command:
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```bash
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# As root:
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su zulip -c '/home/zulip/deployments/current/manage.py register_server'
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# Or as the zulip user, you can skip the `su zulip -c`:
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/home/zulip/deployments/current/manage.py register_server
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# docker-zulip users can run this inside the container with `docker exec`:
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docker exec -it -u zulip <container_name> /home/zulip/deployments/current/manage.py register_server
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```
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This command will print the registration data it would send to the
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mobile push notifications service, ask you to accept the terms of
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service, and if you accept, register your server. If you have trouble,
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email support@zulip.com with the output of this command.
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1. If you or your users have already set up the Zulip mobile app,
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you'll each need to log out and log back in again in order to start
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getting push notifications.
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Congratulations! You've successfully set up the service.
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If you'd like to verify that everything is working, you can do the
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following. Please follow the instructions carefully:
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- [Configure mobile push notifications to always be sent][mobile-notifications-always]
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(normally they're only sent if you're idle, which isn't ideal for
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this sort of testing).
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- On an Android device, download and log in to the
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[Zulip Android app](https://play.google.com/store/apps/details?id=com.zulipmobile).
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If you were already logged in before configuring the server, you'll
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need to log out first, since the app only registers for push
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notifications on login.
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- Hit the home button, so Zulip is running in the background, and then
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have **another user** send you a **private message** (By default,
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Zulip only sends push notifications for private messages sent by other
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users and messages mentioning you). A push notification should appear
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in the Android notification area.
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[mobile-notifications-always]: https://zulip.com/help/test-mobile-notifications
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## Updating your server's registration
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Your server's registration includes the server's hostname and contact
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email address (from `EXTERNAL_HOST` and `ZULIP_ADMINISTRATOR` in
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`/etc/zulip/settings.py`, aka the `--hostname` and `--email` options
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in the installer). You can update your server's registration data by
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running `manage.py register_server` again.
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If you'd like to rotate your server's API key for this service
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(`zulip_org_key`), you need to use
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`manage.py register_server --rotate-key` option; it will automatically
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generate a new `zulip_org_key` and store that new key in
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`/etc/zulip/zulip-secrets.conf`.
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## Why this is necessary
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Both Google's and Apple's push notification services have a security
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model that does not support mutually untrusted self-hosted servers
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sending push notifications to the same app. In particular, when an
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app is published to their respective app stores, one must compile into
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the app a secret corresponding to the server that will be able to
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publish push notifications for the app. This means that it is
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impossible for a single app in their stores to receive push
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notifications from multiple, mutually untrusted, servers.
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Zulip's solution to this problem is to provide a central push
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notification forwarding service, which allows registered Zulip servers
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to send push notifications to the Zulip app indirectly (through the
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forwarding service).
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## Security and privacy
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Use of the push notification bouncer is subject to the
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[Zulipchat Terms of Service](https://zulip.com/terms/). By using
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push notifications, you agree to those terms.
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We've designed this push notification bouncer service with security
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and privacy in mind:
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- A central design goal of the the Push Notification Service is to
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avoid any message content being stored or logged by the service,
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even in error cases.
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- The Push Notification Service only stores the necessary metadata for
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delivering the notifications to the appropriate devices, and nothing
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else:
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- The APNS/FCM tokens needed to securely send mobile push
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notifications to iOS and Android devices, one per device
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registered to be notified by your Zulip server.
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- User ID numbers generated by your Zulip server, needed to route
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a given notification to the appropriate set of mobile devices.
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These user ID numbers are are opaque to the Push Notification
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Service and Kandra Labs.
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- The Push Notification Service receives (but does not store) the
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contents of individual mobile push notifications:
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- The numeric message ID generated by your Zulip server.
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- Metadata on the message's sender (name and avatar URL).
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- Metadata on the message's recipient (stream name + ID, topic,
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private message recipients, etc.).
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- A timestamp.
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- The message's content.
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There's a `PUSH_NOTIFICATION_REDACT_CONTENT` setting available to
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disable any message content being sent via the push notification
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bouncer (i.e. message content will be replaced with
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`***REDACTED***`). Note that this setting makes push notifications
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significantly less usable.
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We plan to
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[replace that setting with end-to-end encryption](https://github.com/zulip/zulip/issues/6954)
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which would eliminate that usability tradeoff and additionally allow
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us to not have any access to the other details mentioned in this
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section.
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- All of the network requests (both from Zulip servers to the Push
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Notification Service and from the Push Notification Service to the
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relevant Google and Apple services) are encrypted over the wire with
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SSL/TLS.
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- The code for the push notification forwarding service is 100% open
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source and available as part of the
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[Zulip server project on GitHub](https://github.com/zulip/zulip).
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- The push notification forwarding servers are professionally managed
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by a small team of security expert engineers.
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If you have any questions about the security model, contact
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support@zulip.com.
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## Submitting statistics
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Systems using the Mobile Push Notifications Service will, by default,
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submit basic usage statistics (e.g. Zulip version, number of users,
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number of messages sent) to the service. These statistics help the
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Zulip open source project understand how many people are using Zulip,
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and help us allocate resources towards supporting self-hosted
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installations.
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Our use of these statistics is governed by the same Terms of Service
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and Privacy Policy that covers the Mobile Push Notifications Service
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itself. If your organization does not want to submit these statistics,
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you can disable this feature at any time by setting
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`SUBMIT_USAGE_STATISTICS=False` in `/etc/zulip/settings.py`.
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## Rate limits
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The Mobile Push Notifications Service API has a very high default rate
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limit of 1000 requests per minute. A Zulip server makes requests to
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this API every time it sends a push notification, which is fairly
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frequent, but we believe it to be unlikely that a self-hosted
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installation will hit this limit.
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This limit is primarily intended to protect the service against DoS
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attacks (intentional or otherwise). If you hit this limit or you
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anticipate that your server will require sending more push
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notifications than the limit permits, please [contact
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support](https://zulip.com/help/contact-support).
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## Sending push notifications directly from your server
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This section documents an alternative way to send push notifications
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that does not involve using the Mobile Push Notifications Service at
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the cost of needing to compile and distribute modified versions of the
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Zulip mobile apps.
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We don't recommend this path -- patching and shipping a production
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mobile app can take dozens of hours to set up even for an experienced
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developer, and even more time to maintain. And it doesn't provide
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material privacy benefits -- your organization's push notification
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data would still go through Apple/Google's servers, just not Kandra
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Labs'. Our view is the correct way to optimize for privacy is
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end-to-end encryption of push notifications. But in the interest of
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transparency, we document in this section roughly what's involved in
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doing so.
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As we discussed above, it is impossible for a single app in their
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stores to receive push notifications from multiple, mutually
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untrusted, servers. The Mobile Push Notification Service is one of
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the possible solutions to this problem. The other possible solution
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is for an individual Zulip server's administrators to build and
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distribute their own copy of the Zulip mobile apps, hardcoding a key
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that they possess.
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This solution is possible with Zulip, but it requires the server
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administrators to publish their own copies of
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the Zulip mobile apps (and there's nothing the Zulip team can do to
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eliminate this onerous requirement).
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The main work is distributing your own copies of the Zulip mobile apps
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configured to use APNS/FCM keys that you generate. This is not for
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the faint of heart! If you haven't done this before, be warned that
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one can easily spend hundreds of dollars (on things like a DUNS number
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registration) and a week struggling through the hoops Apple requires
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to build and distribute an app through the Apple app store, even if
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you're making no code modifications to an app already present in the
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store (as would be the case here). The Zulip mobile app also gets
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frequent updates that you will have to either forgo or republish to
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the app stores yourself.
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If you've done that work, the Zulip server configuration for sending
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push notifications through the new app is quite straightforward:
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- Create a
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[FCM push notifications](https://firebase.google.com/docs/cloud-messaging)
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key in the Google Developer console and set `android_gcm_api_key` in
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`/etc/zulip/zulip-secrets.conf` to that key.
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- Register for a
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[mobile push notification certificate][apple-docs]
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from Apple's developer console. Set `APNS_SANDBOX=False` and
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`APNS_CERT_FILE` to be the path of your APNS certificate file in
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`/etc/zulip/settings.py`.
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- Set the `APNS_TOPIC` and `ZULIP_IOS_APP_ID` settings to the ID for
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your app (for the official Zulip apps, they are both `org.zulip.Zulip`).
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- Restart the Zulip server.
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[apple-docs]: https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/APNSOverview.html
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