Add missing worker settings to shared configuration (#14748)

* Add missing worker settings to shared configuration

* newsfile

* update docs after review

* more update for doc

* This -> These

Co-authored-by: David Robertson <david.m.robertson1@gmail.com>

changelog.d/14748.doc

@@ -0,0 +1 @@
+Add missing worker settings to shared configuration documentation.

docs/usage/configuration/config_documentation.md

@@ -3864,6 +3864,48 @@ Example configuration:
 ```yaml
 run_background_tasks_on: worker1
 ```
+---
+### `update_user_directory_from_worker`
+
+The [worker](../../workers.md#updating-the-user-directory) that is used to
+update the user directory. If not provided this defaults to the main process.
+
+Example configuration:
+```yaml
+update_user_directory_from_worker: worker1
+```
+
+_Added in Synapse 1.59.0._
+
+---
+### `notify_appservices_from_worker`
+
+The [worker](../../workers.md#notifying-application-services) that is used to
+send output traffic to Application Services. If not provided this defaults
+to the main process.
+
+Example configuration:
+```yaml
+notify_appservices_from_worker: worker1
+```
+
+_Added in Synapse 1.59.0._
+
+---
+### `media_instance_running_background_jobs`
+
+The [worker](../../workers.md#synapseappmedia_repository) that is used to run
+background tasks for media repository. If running multiple media repositories
+you must configure a single instance to run the background tasks. If not provided
+this defaults to the main process or your single `media_repository` worker.
+
+Example configuration:
+```yaml
+media_instance_running_background_jobs: worker1
+```
+
+_Added in Synapse 1.16.0._
+
 ---
 ### `redis`
 

docs/workers.md

@@ -465,7 +465,8 @@ An example for a dedicated background worker instance:
 
 You can designate one generic worker to update the user directory.
 
-Specify its name in the shared configuration as follows:
+Specify its name in the [shared configuration](usage/configuration/config_documentation.md#update_user_directory_from_worker)
+as follows:
 
 ```yaml
 update_user_directory_from_worker: worker_name
@@ -490,7 +491,8 @@ worker application type.
 
 You can designate one generic worker to send output traffic to Application Services.
 Doesn't handle any REST endpoints itself, but you should specify its name in the
-shared configuration as follows:
+[shared configuration](usage/configuration/config_documentation.md#notify_appservices_from_worker)
+as follows:
 
 ```yaml
 notify_appservices_from_worker: worker_name
@@ -502,11 +504,38 @@ after setting this option in the shared configuration!
 This style of configuration supersedes the legacy `synapse.app.appservice`
 worker application type.
 
+#### Push Notifications
+
+You can designate generic worker to sending push notifications to
+a [push gateway](https://spec.matrix.org/v1.5/push-gateway-api/) such as
+[sygnal](https://github.com/matrix-org/sygnal) and email.
+
+This will stop the main process sending push notifications.
+
+The workers responsible for sending push notifications can be defined using the
+[`pusher_instances`](usage/configuration/config_documentation.md#pusher_instances)
+option. For example:
+
+```yaml
+pusher_instances:
+  - pusher_worker1
+  - pusher_worker2
+```
+
+Multiple workers can be added to this map, in which case the work is balanced
+across them. Ensure the main process and all pusher workers are restarted after changing
+this option.
+
+These workers don't need to accept incoming HTTP requests to send push notifications,
+so no additional reverse proxy configuration is required for pusher workers.
+
+This style of configuration supersedes the legacy `synapse.app.pusher`
+worker application type.
 
 ### `synapse.app.pusher`
 
 It is likely this option will be deprecated in the future and is not recommended for new
-installations. Instead, [use `synapse.app.generic_worker` with the `pusher_instances`](usage/configuration/config_documentation.md#pusher_instances).
+installations. Instead, [use `synapse.app.generic_worker` with the `pusher_instances`](#push-notifications).
 
 Handles sending push notifications to sygnal and email. Doesn't handle any
 REST endpoints itself, but you should set
@@ -606,7 +635,9 @@ expose the `media` resource. For example:
 ```
 
 Note that if running multiple media repositories they must be on the same server
-and you must configure a single instance to run the background tasks, e.g.:
+and you must specify a single instance to run the background tasks in the
+[shared configuration](usage/configuration/config_documentation.md#media_instance_running_background_jobs),
+e.g.:
 
 ```yaml
 media_instance_running_background_jobs: "media-repository-1"