Announce sliding-sync support

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/2515

CHANGELOG.md

@@ -1,3 +1,14 @@
+# 2023-03-07
+
+## Sliding Sync Proxy (Element X) support
+
+Thanks to [Benjamin Kampmann](https://github.com/gnunicorn) for [getting it started](https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/2515), [FSG-Cat](https://github.com/FSG-Cat) for fixing it up and me ([Slavi](https://github.com/spantaleev)) for polishing it up, the playbook can now install and configure the [sliding-sync proxy](https://github.com/matrix-org/sliding-sync).
+
+The new Element X clients ([Element X iOS](https://github.com/vector-im/element-x-ios) and [Element X Android](https://github.com/vector-im/element-x-android)) require the `sliding-sync` proxy to do their job. These clients are still in beta, and now playbook users can easily give them a try and help test them thanks to us having `sliding-sync` support.
+
+To get started, see our [Setting up Sliding Sync Proxy](docs/configuring-playbook-sliding-sync-proxy.md) documentation page.
+
+
 # 2023-03-02
 
 ## The matrix-etherpad role lives independently now

README.md

@@ -162,6 +162,7 @@ Various services that don't fit any other category.
 
 | Name | Default? | Description | Documentation |
 | ---- | -------- | ----------- | ------------- |
+| [sliding-sync](https://github.com/matrix-org/sliding-sync)| x | Sliding Sync support for clients which require it (e.g. Element X) | [Link](docs/configuring-playbook-sliding-sync-proxy.md) |
 | [synapse-simple-antispam](https://github.com/t2bot/synapse-simple-antispam) (advanced) | x | A spam checker module | [Link](docs/configuring-playbook-synapse-simple-antispam.md) |
 | [Matrix Corporal](https://github.com/devture/matrix-corporal) (advanced) | x | Reconciliator and gateway for a managed Matrix server | [Link](docs/configuring-playbook-matrix-corporal.md) |
 | [Etherpad](https://etherpad.org) | x | An open source collaborative text editor | [Link](docs/configuring-playbook-etherpad.md) |

docs/configuring-playbook-sliding-sync-proxy.md

@@ -0,0 +1,47 @@
+# Setting up Sliding Sync Proxy (optional)
+
+The playbook can install and configure [sliding-sync](https://github.com/matrix-org/sliding-sync) proxy for you.
+
+Sliding Sync is an implementation of [MSC3575](https://github.com/matrix-org/matrix-spec-proposals/blob/kegan/sync-v3/proposals/3575-sync.md) and a prerequisite for running the new (still beta) Element X clients ([Element X iOS](https://github.com/vector-im/element-x-ios) and [Element X Android](https://github.com/vector-im/element-x-android)).
+
+See the project's [documentation](https://github.com/matrix-org/sliding-syncb) to learn more.
+
+**NOTE**: The Sliding Sync proxy **only works with the Traefik reverse-proxy**. If you have an old server installation (from the time `matrix-nginx-proxy` was our default reverse-proxy - `matrix_playbook_reverse_proxy_type: playbook-managed-nginx`), you won't be able to use Sliding Sync.
+
+
+## Decide on a domain and path
+
+By default, the Sliding Sync proxy is configured to be served on the Matrix domain (`matrix.DOMAIN`, controlled by `matrix_server_fqn_matrix`), under the `/sliding-sync` path.
+
+This makes it easy to set it up, **without** having to [adjust your DNS records](#adjusting-dns-records).
+
+If you'd like to run the Sliding Sync proxy on another hostname or path, use the `matrix_sliding_sync_hostname` and `matrix_sliding_sync_path_prefix` variables.
+
+
+## Adjusting DNS records
+
+If you've changed the default hostame, **you may need to adjust your DNS** records.
+
+
+## Adjusting the playbook configuration
+
+Add the following configuration to your `inventory/host_vars/matrix.DOMAIN/vars.yml` file:
+
+```yaml
+matrix_sliding_sync_enabled: true
+```
+
+
+## Installing
+
+After potentially [adjusting DNS records](#adjusting-dns-records) and configuring the playbook, run the [installation](installing.md) command again: `just install-all`.
+
+
+## Usage
+
+You **don't need to do anything special** to make use of the Sliding Sync Proxy.
+Simply open your client which supports Sliding Sync (like Element X) and log in.
+
+When the Sliding Sync proxy is [installed](#installing), your `/.well-known/matrix/client` file is also updated. A new `org.matrix.msc3575.proxy` section and `url` property are added there and made to point to your Sliding Sync proxy's base URL (e.g. `https://matrix.DOMAIN/sliding-sync`).
+
+This allows clients which support Sliding Sync to detect the Sliding Sync Proxy's URL and make use of it.

docs/configuring-playbook.md

@@ -195,6 +195,8 @@ When you're done with all the configuration you'd like to do, continue with [Ins
 
 ### Other specialized services
 
+- [Setting up the Sliding Sync Proxy](configuring-playbook-sliding-sync-proxy.md) for clients which require Sliding Sync support (like Element X) (optional)
+
 - [Setting up the Sygnal push gateway](configuring-playbook-sygnal.md) (optional)
 
 - [Setting up the ntfy push notifications server](configuring-playbook-ntfy.md) (optional)