436 lines
17 KiB
Markdown
436 lines
17 KiB
Markdown
# Scaling synapse via workers
|
|
|
|
For small instances it recommended to run Synapse in monolith mode (the
|
|
default). For larger instances where performance is a concern it can be helpful
|
|
to split out functionality into multiple separate python processes. These
|
|
processes are called 'workers', and are (eventually) intended to scale
|
|
horizontally independently.
|
|
|
|
Synapse's worker support is under active development and subject to change as
|
|
we attempt to rapidly scale ever larger Synapse instances. However we are
|
|
documenting it here to help admins needing a highly scalable Synapse instance
|
|
similar to the one running `matrix.org`.
|
|
|
|
All processes continue to share the same database instance, and as such,
|
|
workers only work with PostgreSQL-based Synapse deployments. SQLite should only
|
|
be used for demo purposes and any admin considering workers should already be
|
|
running PostgreSQL.
|
|
|
|
## Main process/worker communication
|
|
|
|
The processes communicate with each other via a Synapse-specific protocol called
|
|
'replication' (analogous to MySQL- or Postgres-style database replication) which
|
|
feeds streams of newly written data between processes so they can be kept in
|
|
sync with the database state.
|
|
|
|
Additionally, processes may make HTTP requests to each other. Typically this is
|
|
used for operations which need to wait for a reply - such as sending an event.
|
|
|
|
As of Synapse v1.13.0, it is possible to configure Synapse to send replication
|
|
via a [Redis pub/sub channel](https://redis.io/topics/pubsub), and is now the
|
|
recommended way of configuring replication. This is an alternative to the old
|
|
direct TCP connections to the main process: rather than all the workers
|
|
connecting to the main process, all the workers and the main process connect to
|
|
Redis, which relays replication commands between processes. This can give a
|
|
significant cpu saving on the main process and will be a prerequisite for
|
|
upcoming performance improvements.
|
|
|
|
(See the [Architectural diagram](#architectural-diagram) section at the end for
|
|
a visualisation of what this looks like)
|
|
|
|
|
|
## Setting up workers
|
|
|
|
A Redis server is required to manage the communication between the processes.
|
|
(The older direct TCP connections are now deprecated.) The Redis server
|
|
should be installed following the normal procedure for your distribution (e.g.
|
|
`apt install redis-server` on Debian). It is safe to use an existing Redis
|
|
deployment if you have one.
|
|
|
|
Once installed, check that Redis is running and accessible from the host running
|
|
Synapse, for example by executing `echo PING | nc -q1 localhost 6379` and seeing
|
|
a response of `+PONG`.
|
|
|
|
The appropriate dependencies must also be installed for Synapse. If using a
|
|
virtualenv, these can be installed with:
|
|
|
|
```sh
|
|
pip install matrix-synapse[redis]
|
|
```
|
|
|
|
Note that these dependencies are included when synapse is installed with `pip
|
|
install matrix-synapse[all]`. They are also included in the debian packages from
|
|
`matrix.org` and in the docker images at
|
|
https://hub.docker.com/r/matrixdotorg/synapse/.
|
|
|
|
To make effective use of the workers, you will need to configure an HTTP
|
|
reverse-proxy such as nginx or haproxy, which will direct incoming requests to
|
|
the correct worker, or to the main synapse instance. See [reverse_proxy.md](reverse_proxy.md)
|
|
for information on setting up a reverse proxy.
|
|
|
|
To enable workers you should create a configuration file for each worker
|
|
process. Each worker configuration file inherits the configuration of the shared
|
|
homeserver configuration file. You can then override configuration specific to
|
|
that worker, e.g. the HTTP listener that it provides (if any); logging
|
|
configuration; etc. You should minimise the number of overrides though to
|
|
maintain a usable config.
|
|
|
|
Next you need to add both a HTTP replication listener and redis config to the
|
|
shared Synapse configuration file (`homeserver.yaml`). For example:
|
|
|
|
```yaml
|
|
# extend the existing `listeners` section. This defines the ports that the
|
|
# main process will listen on.
|
|
listeners:
|
|
# The HTTP replication port
|
|
- port: 9093
|
|
bind_address: '127.0.0.1'
|
|
type: http
|
|
resources:
|
|
- names: [replication]
|
|
|
|
redis:
|
|
enabled: true
|
|
```
|
|
|
|
See the sample config for the full documentation of each option.
|
|
|
|
Under **no circumstances** should the replication listener be exposed to the
|
|
public internet; it has no authentication and is unencrypted.
|
|
|
|
In the config file for each worker, you must specify the type of worker
|
|
application (`worker_app`), and you should specify a unqiue name for the worker
|
|
(`worker_name`). The currently available worker applications are listed below.
|
|
You must also specify the HTTP replication endpoint that it should talk to on
|
|
the main synapse process. `worker_replication_host` should specify the host of
|
|
the main synapse and `worker_replication_http_port` should point to the HTTP
|
|
replication port. If the worker will handle HTTP requests then the
|
|
`worker_listeners` option should be set with a `http` listener, in the same way
|
|
as the `listeners` option in the shared config.
|
|
|
|
For example:
|
|
|
|
```yaml
|
|
worker_app: synapse.app.generic_worker
|
|
worker_name: worker1
|
|
|
|
# The replication listener on the main synapse process.
|
|
worker_replication_host: 127.0.0.1
|
|
worker_replication_http_port: 9093
|
|
|
|
worker_listeners:
|
|
- type: http
|
|
port: 8083
|
|
resources:
|
|
- names:
|
|
- client
|
|
- federation
|
|
|
|
worker_log_config: /home/matrix/synapse/config/worker1_log_config.yaml
|
|
```
|
|
|
|
...is a full configuration for a generic worker instance, which will expose a
|
|
plain HTTP endpoint on port 8083 separately serving various endpoints, e.g.
|
|
`/sync`, which are listed below.
|
|
|
|
Obviously you should configure your reverse-proxy to route the relevant
|
|
endpoints to the worker (`localhost:8083` in the above example).
|
|
|
|
Finally, you need to start your worker processes. This can be done with either
|
|
`synctl` or your distribution's preferred service manager such as `systemd`. We
|
|
recommend the use of `systemd` where available: for information on setting up
|
|
`systemd` to start synapse workers, see
|
|
[systemd-with-workers](systemd-with-workers). To use `synctl`, see
|
|
[synctl_workers.md](synctl_workers.md).
|
|
|
|
|
|
## Available worker applications
|
|
|
|
### `synapse.app.generic_worker`
|
|
|
|
This worker can handle API requests matching the following regular
|
|
expressions:
|
|
|
|
# Sync requests
|
|
^/_matrix/client/(v2_alpha|r0)/sync$
|
|
^/_matrix/client/(api/v1|v2_alpha|r0)/events$
|
|
^/_matrix/client/(api/v1|r0)/initialSync$
|
|
^/_matrix/client/(api/v1|r0)/rooms/[^/]+/initialSync$
|
|
|
|
# Federation requests
|
|
^/_matrix/federation/v1/event/
|
|
^/_matrix/federation/v1/state/
|
|
^/_matrix/federation/v1/state_ids/
|
|
^/_matrix/federation/v1/backfill/
|
|
^/_matrix/federation/v1/get_missing_events/
|
|
^/_matrix/federation/v1/publicRooms
|
|
^/_matrix/federation/v1/query/
|
|
^/_matrix/federation/v1/make_join/
|
|
^/_matrix/federation/v1/make_leave/
|
|
^/_matrix/federation/v1/send_join/
|
|
^/_matrix/federation/v2/send_join/
|
|
^/_matrix/federation/v1/send_leave/
|
|
^/_matrix/federation/v2/send_leave/
|
|
^/_matrix/federation/v1/invite/
|
|
^/_matrix/federation/v2/invite/
|
|
^/_matrix/federation/v1/query_auth/
|
|
^/_matrix/federation/v1/event_auth/
|
|
^/_matrix/federation/v1/exchange_third_party_invite/
|
|
^/_matrix/federation/v1/user/devices/
|
|
^/_matrix/federation/v1/get_groups_publicised$
|
|
^/_matrix/key/v2/query
|
|
|
|
# Inbound federation transaction request
|
|
^/_matrix/federation/v1/send/
|
|
|
|
# Client API requests
|
|
^/_matrix/client/(api/v1|r0|unstable)/publicRooms$
|
|
^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/joined_members$
|
|
^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/context/.*$
|
|
^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/members$
|
|
^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/state$
|
|
^/_matrix/client/(api/v1|r0|unstable)/account/3pid$
|
|
^/_matrix/client/(api/v1|r0|unstable)/keys/query$
|
|
^/_matrix/client/(api/v1|r0|unstable)/keys/changes$
|
|
^/_matrix/client/versions$
|
|
^/_matrix/client/(api/v1|r0|unstable)/voip/turnServer$
|
|
^/_matrix/client/(api/v1|r0|unstable)/joined_groups$
|
|
^/_matrix/client/(api/v1|r0|unstable)/publicised_groups$
|
|
^/_matrix/client/(api/v1|r0|unstable)/publicised_groups/
|
|
|
|
# Registration/login requests
|
|
^/_matrix/client/(api/v1|r0|unstable)/login$
|
|
^/_matrix/client/(r0|unstable)/register$
|
|
^/_matrix/client/(r0|unstable)/auth/.*/fallback/web$
|
|
|
|
# Event sending requests
|
|
^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/send
|
|
^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/state/
|
|
^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/(join|invite|leave|ban|unban|kick)$
|
|
^/_matrix/client/(api/v1|r0|unstable)/join/
|
|
^/_matrix/client/(api/v1|r0|unstable)/profile/
|
|
|
|
|
|
Additionally, the following REST endpoints can be handled for GET requests:
|
|
|
|
^/_matrix/federation/v1/groups/
|
|
|
|
Pagination requests can also be handled, but all requests for a given
|
|
room must be routed to the same instance. Additionally, care must be taken to
|
|
ensure that the purge history admin API is not used while pagination requests
|
|
for the room are in flight:
|
|
|
|
^/_matrix/client/(api/v1|r0|unstable)/rooms/.*/messages$
|
|
|
|
Note that a HTTP listener with `client` and `federation` resources must be
|
|
configured in the `worker_listeners` option in the worker config.
|
|
|
|
|
|
#### Load balancing
|
|
|
|
It is possible to run multiple instances of this worker app, with incoming requests
|
|
being load-balanced between them by the reverse-proxy. However, different endpoints
|
|
have different characteristics and so admins
|
|
may wish to run multiple groups of workers handling different endpoints so that
|
|
load balancing can be done in different ways.
|
|
|
|
For `/sync` and `/initialSync` requests it will be more efficient if all
|
|
requests from a particular user are routed to a single instance. Extracting a
|
|
user ID from the access token or `Authorization` header is currently left as an
|
|
exercise for the reader. Admins may additionally wish to separate out `/sync`
|
|
requests that have a `since` query parameter from those that don't (and
|
|
`/initialSync`), as requests that don't are known as "initial sync" that happens
|
|
when a user logs in on a new device and can be *very* resource intensive, so
|
|
isolating these requests will stop them from interfering with other users ongoing
|
|
syncs.
|
|
|
|
Federation and client requests can be balanced via simple round robin.
|
|
|
|
The inbound federation transaction request `^/_matrix/federation/v1/send/`
|
|
should be balanced by source IP so that transactions from the same remote server
|
|
go to the same process.
|
|
|
|
Registration/login requests can be handled separately purely to help ensure that
|
|
unexpected load doesn't affect new logins and sign ups.
|
|
|
|
Finally, event sending requests can be balanced by the room ID in the URI (or
|
|
the full URI, or even just round robin), the room ID is the path component after
|
|
`/rooms/`. If there is a large bridge connected that is sending or may send lots
|
|
of events, then a dedicated set of workers can be provisioned to limit the
|
|
effects of bursts of events from that bridge on events sent by normal users.
|
|
|
|
#### Stream writers
|
|
|
|
Additionally, there is *experimental* support for moving writing of specific
|
|
streams (such as events) off of the main process to a particular worker. (This
|
|
is only supported with Redis-based replication.)
|
|
|
|
Currently support streams are `events` and `typing`.
|
|
|
|
To enable this, the worker must have a HTTP replication listener configured,
|
|
have a `worker_name` and be listed in the `instance_map` config. For example to
|
|
move event persistence off to a dedicated worker, the shared configuration would
|
|
include:
|
|
|
|
```yaml
|
|
instance_map:
|
|
event_persister1:
|
|
host: localhost
|
|
port: 8034
|
|
|
|
streams_writers:
|
|
events: event_persister1
|
|
```
|
|
|
|
|
|
### `synapse.app.pusher`
|
|
|
|
Handles sending push notifications to sygnal and email. Doesn't handle any
|
|
REST endpoints itself, but you should set `start_pushers: False` in the
|
|
shared configuration file to stop the main synapse sending push notifications.
|
|
|
|
Note this worker cannot be load-balanced: only one instance should be active.
|
|
|
|
### `synapse.app.appservice`
|
|
|
|
Handles sending output traffic to Application Services. Doesn't handle any
|
|
REST endpoints itself, but you should set `notify_appservices: False` in the
|
|
shared configuration file to stop the main synapse sending appservice notifications.
|
|
|
|
Note this worker cannot be load-balanced: only one instance should be active.
|
|
|
|
|
|
### `synapse.app.federation_sender`
|
|
|
|
Handles sending federation traffic to other servers. Doesn't handle any
|
|
REST endpoints itself, but you should set `send_federation: False` in the
|
|
shared configuration file to stop the main synapse sending this traffic.
|
|
|
|
If running multiple federation senders then you must list each
|
|
instance in the `federation_sender_instances` option by their `worker_name`.
|
|
All instances must be stopped and started when adding or removing instances.
|
|
For example:
|
|
|
|
```yaml
|
|
federation_sender_instances:
|
|
- federation_sender1
|
|
- federation_sender2
|
|
```
|
|
|
|
### `synapse.app.media_repository`
|
|
|
|
Handles the media repository. It can handle all endpoints starting with:
|
|
|
|
/_matrix/media/
|
|
|
|
... and the following regular expressions matching media-specific administration APIs:
|
|
|
|
^/_synapse/admin/v1/purge_media_cache$
|
|
^/_synapse/admin/v1/room/.*/media.*$
|
|
^/_synapse/admin/v1/user/.*/media.*$
|
|
^/_synapse/admin/v1/media/.*$
|
|
^/_synapse/admin/v1/quarantine_media/.*$
|
|
|
|
You should also set `enable_media_repo: False` in the shared configuration
|
|
file to stop the main synapse running background jobs related to managing the
|
|
media repository.
|
|
|
|
In the `media_repository` worker configuration file, configure the http listener to
|
|
expose the `media` resource. For example:
|
|
|
|
```yaml
|
|
worker_listeners:
|
|
- type: http
|
|
port: 8085
|
|
resources:
|
|
- names:
|
|
- media
|
|
```
|
|
|
|
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.:
|
|
|
|
```yaml
|
|
media_instance_running_background_jobs: "media-repository-1"
|
|
```
|
|
|
|
### `synapse.app.user_dir`
|
|
|
|
Handles searches in the user directory. It can handle REST endpoints matching
|
|
the following regular expressions:
|
|
|
|
^/_matrix/client/(api/v1|r0|unstable)/user_directory/search$
|
|
|
|
When using this worker you must also set `update_user_directory: False` in the
|
|
shared configuration file to stop the main synapse running background
|
|
jobs related to updating the user directory.
|
|
|
|
### `synapse.app.frontend_proxy`
|
|
|
|
Proxies some frequently-requested client endpoints to add caching and remove
|
|
load from the main synapse. It can handle REST endpoints matching the following
|
|
regular expressions:
|
|
|
|
^/_matrix/client/(api/v1|r0|unstable)/keys/upload
|
|
|
|
If `use_presence` is False in the homeserver config, it can also handle REST
|
|
endpoints matching the following regular expressions:
|
|
|
|
^/_matrix/client/(api/v1|r0|unstable)/presence/[^/]+/status
|
|
|
|
This "stub" presence handler will pass through `GET` request but make the
|
|
`PUT` effectively a no-op.
|
|
|
|
It will proxy any requests it cannot handle to the main synapse instance. It
|
|
must therefore be configured with the location of the main instance, via
|
|
the `worker_main_http_uri` setting in the `frontend_proxy` worker configuration
|
|
file. For example:
|
|
|
|
worker_main_http_uri: http://127.0.0.1:8008
|
|
|
|
### Historical apps
|
|
|
|
*Note:* Historically there used to be more apps, however they have been
|
|
amalgamated into a single `synapse.app.generic_worker` app. The remaining apps
|
|
are ones that do specific processing unrelated to requests, e.g. the `pusher`
|
|
that handles sending out push notifications for new events. The intention is for
|
|
all these to be folded into the `generic_worker` app and to use config to define
|
|
which processes handle the various proccessing such as push notifications.
|
|
|
|
|
|
## Architectural diagram
|
|
|
|
The following shows an example setup using Redis and a reverse proxy:
|
|
|
|
```
|
|
Clients & Federation
|
|
|
|
|
v
|
|
+-----------+
|
|
| |
|
|
| Reverse |
|
|
| Proxy |
|
|
| |
|
|
+-----------+
|
|
| | |
|
|
| | | HTTP requests
|
|
+-------------------+ | +-----------+
|
|
| +---+ |
|
|
| | |
|
|
v v v
|
|
+--------------+ +--------------+ +--------------+ +--------------+
|
|
| Main | | Generic | | Generic | | Event |
|
|
| Process | | Worker 1 | | Worker 2 | | Persister |
|
|
+--------------+ +--------------+ +--------------+ +--------------+
|
|
^ ^ | ^ | | ^ | ^ ^
|
|
| | | | | | | | | |
|
|
| | | | | HTTP | | | | |
|
|
| +----------+<--|---|---------+ | | | |
|
|
| | +-------------|-->+----------+ |
|
|
| | | |
|
|
| | | |
|
|
v v v v
|
|
====================================================================
|
|
Redis pub/sub channel
|
|
```
|