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.
The workers communicate with the master process via a Synapse-specific protocol called 'replication' (analogous to MySQL- or Postgres-style database replication) which feeds a stream of relevant data from the master to the workers so they can be kept in sync with the master process and database state.
Additionally, workers may make HTTP requests to the master, to send information in the other direction. Typically this is used for operations which need to wait for a reply - such as sending an event.
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. Note that this includes requests made to the federation port. See reverse_proxy.md for information on setting up a reverse proxy.
To enable workers, you need to add two replication listeners to the
main Synapse configuration file (homeserver.yaml
). For example:
listeners:
# The TCP replication port
- port: 9092
bind_address: '127.0.0.1'
type: replication
# The HTTP replication port
- port: 9093
bind_address: '127.0.0.1'
type: http
resources:
- names: [replication]
Under no circumstances should these replication API listeners be exposed to the public internet; they have no authentication and are unencrypted.
You should then create a set of configs for the various worker processes. Each worker configuration file inherits the configuration of the main 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.
In the config file for each worker, you must specify the type of worker
application (worker_app
). The currently available worker applications are
listed below. You must also specify the replication endpoints that it should
talk to on the main synapse process. worker_replication_host
should specify
the host of the main synapse, worker_replication_port
should point to the TCP
replication listener port and worker_replication_http_port
should point to
the HTTP replication port.
For example:
worker_app: synapse.app.synchrotron
# The replication listener on the synapse to talk to.
worker_replication_host: 127.0.0.1
worker_replication_port: 9092
worker_replication_http_port: 9093
worker_listeners:
- type: http
port: 8083
resources:
- names:
- client
worker_log_config: /home/matrix/synapse/config/synchrotron_log_config.yaml
...is a full configuration for a synchrotron worker instance, which will expose a
plain HTTP /sync
endpoint on port 8083 separately from the /sync
endpoint provided
by the main synapse.
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. To use synctl
, see below.
As of Synapse v1.13.0, it is possible to configure Synapse to send replication via a Redis pub/sub channel. This is an alternative to direct TCP connections to the master: rather than all the workers connecting to the master, all the workers and the master connect to Redis, which relays replication commands between processes. This can give a significant cpu saving on the master and will be a prerequisite for upcoming performance improvements.
Note that this support is currently experimental; you may experience lost messages and similar problems! It is strongly recommended that admins setting up workers for the first time use direct TCP replication as above.
To configure Synapse to use Redis:
apt install redis-server
. (It is safe to use an
existing Redis deployment if you have one: we use a pub/sub stream named
according to the server_name
of your synapse server.)echo PING | nc -q1
localhost 6379
and get a response of +PONG
.Install the python prerequisites. If you installed synapse into a virtualenv, this can be done with:
pip install matrix-synapse[redis]
The debian packages from matrix.org already include the required dependencies.
Add config to the shared configuration (homeserver.yaml
):
redis:
enabled: true
Optional parameters which can go alongside enabled
are host
, port
,
password
. Normally none of these are required.
Restart master and all workers.
Once redis replication is in use, worker_replication_port
is redundant and
can be removed from the worker configuration files. Similarly, the
configuration for the listener
for the TCP replication port can be removed
from the main configuration file. Note that the HTTP replication port is
still required.
If you want to use synctl
to manage your synapse processes, you will need to
create an an additional configuration file for the master synapse process. That
configuration should look like this:
worker_app: synapse.app.homeserver
Additionally, each worker app must be configured with the name of a "pid file", to which it will write its process ID when it starts. For example, for a synchrotron, you might write:
worker_pid_file: /home/matrix/synapse/synchrotron.pid
Finally, to actually run your worker-based synapse, you must pass synctl the -a
commandline option to tell it to operate on all the worker configurations found
in the given directory, e.g.:
synctl -a $CONFIG/workers start
Currently one should always restart all workers when restarting or upgrading synapse, unless you explicitly know it's safe not to. For instance, restarting synapse without restarting all the synchrotrons may result in broken typing notifications.
To manipulate a specific worker, you pass the -w option to synctl:
synctl -w $CONFIG/workers/synchrotron.yaml restart
synapse.app.pusher
Handles sending push notifications to sygnal and email. Doesn't handle any
REST endpoints itself, but you should set start_pushers: False
in the
shared configuration file to stop the main synapse sending these notifications.
Note this worker cannot be load-balanced: only one instance should be active.
synapse.app.synchrotron
The synchrotron handles sync
requests from clients. In particular, it can
handle REST endpoints matching the following regular expressions:
^/_matrix/client/(v2_alpha|r0)/sync$
^/_matrix/client/(api/v1|v2_alpha|r0)/events$
^/_matrix/client/(api/v1|r0)/initialSync$
^/_matrix/client/(api/v1|r0)/rooms/[^/]+/initialSync$
The above endpoints should all be routed to the synchrotron worker by the reverse-proxy configuration.
It is possible to run multiple instances of the synchrotron to scale horizontally. In this case the reverse-proxy should be configured to load-balance across the instances, though it will be more efficient if all requests from a particular user are routed to a single instance. Extracting a userid from the access token is currently left as an exercise for the reader.
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 these notifications.
Note this worker cannot be load-balanced: only one instance should be active.
synapse.app.federation_reader
Handles a subset of federation endpoints. In particular, it can handle REST endpoints matching the following regular expressions:
^/_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/send/
^/_matrix/federation/v1/get_groups_publicised$
^/_matrix/key/v2/query
Additionally, the following REST endpoints can be handled for GET requests:
^/_matrix/federation/v1/groups/
The above endpoints should all be routed to the federation_reader worker by the reverse-proxy configuration.
The ^/_matrix/federation/v1/send/
endpoint must only be handled by a single
instance.
Note that federation
must be added to the listener resources in the worker config:
worker_app: synapse.app.federation_reader
...
worker_listeners:
- type: http
port: <port>
resources:
- names:
- federation
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.
Note this worker cannot be load-balanced: only one instance should be active.
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:
worker_listeners:
- type: http
port: 8085
resources:
- names:
- media
Note this worker cannot be load-balanced: only one instance should be active.
synapse.app.client_reader
Handles client API endpoints. It can handle REST endpoints matching the following regular expressions:
^/_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)/login$
^/_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/
Additionally, the following REST endpoints can be handled for GET requests:
^/_matrix/client/(api/v1|r0|unstable)/pushrules/.*$
^/_matrix/client/(api/v1|r0|unstable)/groups/.*$
^/_matrix/client/(api/v1|r0|unstable)/user/[^/]*/account_data/
^/_matrix/client/(api/v1|r0|unstable)/user/[^/]*/rooms/[^/]*/account_data/
Additionally, the following REST endpoints can be handled, but all requests must be routed to the same instance:
^/_matrix/client/(r0|unstable)/register$
^/_matrix/client/(r0|unstable)/auth/.*/fallback/web$
Pagination requests can also be handled, but all requests with the same path 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$
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
synapse.app.event_creator
Handles some event creation. It can handle REST endpoints matching:
^/_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/
It will create events locally and then send them on to the main synapse instance to be persisted and handled.