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diff --git a/docs/workers.md b/docs/workers.md index f4cbbc0400..80b65a0cec 100644 --- a/docs/workers.md +++ b/docs/workers.md @@ -1,10 +1,10 @@ # 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. +For small instances it recommended to run Synapse in the default monolith mode. +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 @@ -16,69 +16,115 @@ 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. -## Master/worker communication +## 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. + +When configured to do so, Synapse uses a +[Redis pub/sub channel](https://redis.io/topics/pubsub) to send the replication +stream between all configured Synapse processes. Additionally, processes may +make HTTP requests to each other, primarily for operations which need to wait +for a reply ─ such as sending an event. + +Redis support was added in v1.13.0 with it becoming the recommended method in +v1.18.0. It replaced the old direct TCP connections (which is deprecated as of +v1.18.0) to the main process. With Redis, 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. + -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. +## Setting up workers -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. +A Redis server is required to manage the communication between the processes. +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. -## Configuration +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. Note that this includes -requests made to the federation port. See [reverse_proxy.md](reverse_proxy.md) -for information on setting up a reverse proxy. +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. + + +### Shared Configuration -To enable workers, you need to add *two* replication listeners to the -main Synapse configuration file (`homeserver.yaml`). For example: +Next you need to add both a HTTP replication listener, used for HTTP requests +between processes, 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 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] + +redis: + enabled: true ``` -Under **no circumstances** should these replication API listeners be exposed to -the public internet; they have no authentication and are unencrypted. +See the sample config for the full documentation of each option. -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. +Under **no circumstances** should the replication listener be exposed to the +public internet; it has no authentication and is unencrypted. + + +### Worker Configuration 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. +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.synchrotron +worker_app: synapse.app.generic_worker +worker_name: worker1 -# The replication listener on the synapse to talk to. +# The replication listener on the main synapse process. worker_replication_host: 127.0.0.1 -worker_replication_port: 9092 worker_replication_http_port: 9093 worker_listeners: @@ -87,13 +133,14 @@ worker_listeners: resources: - names: - client + - federation -worker_log_config: /home/matrix/synapse/config/synchrotron_log_config.yaml +worker_log_config: /home/matrix/synapse/config/worker1_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. +...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). @@ -102,127 +149,24 @@ 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 below. +[systemd-with-workers](systemd-with-workers). To use `synctl`, see +[synctl_workers.md](synctl_workers.md). -### **Experimental** support for replication over redis - -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). 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: - -1. Install Redis following the normal procedure for your distribution - for - example, on Debian, `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.) -2. Check Redis is running and accessible: you should be able to `echo PING | nc -q1 - localhost 6379` and get a response of `+PONG`. -3. Install the python prerequisites. If you installed synapse into a - virtualenv, this can be done with: - ```sh - pip install matrix-synapse[redis] - ``` - The debian packages from matrix.org already include the required - dependencies. -4. Add config to the shared configuration (`homeserver.yaml`): - ```yaml - redis: - enabled: true - ``` - Optional parameters which can go alongside `enabled` are `host`, `port`, - `password`. Normally none of these are required. -5. 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. - -### Using synctl - -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: - -```yaml -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: - -```yaml -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 $CONFIG/workers/synchrotron.yaml restart ## Available worker applications -### `synapse.app.pusher` - -Handles sending push notifications to sygnal and email. Doesn't handle any -REST endpoints itself, but you should set `start_pushers: False` in the -shared configuration file to stop the main synapse sending these notifications. - -Note this worker cannot be load-balanced: only one instance should be active. - -### `synapse.app.synchrotron` +### `synapse.app.generic_worker` -The synchrotron handles `sync` requests from clients. In particular, it can -handle REST endpoints matching the following regular expressions: +This worker can handle API requests matching the following regular +expressions: + # Sync requests ^/_matrix/client/(v2_alpha|r0)/sync$ ^/_matrix/client/(api/v1|v2_alpha|r0)/events$ ^/_matrix/client/(api/v1|r0)/initialSync$ ^/_matrix/client/(api/v1|r0)/rooms/[^/]+/initialSync$ -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: - + # Federation requests ^/_matrix/federation/v1/event/ ^/_matrix/federation/v1/state/ ^/_matrix/federation/v1/state_ids/ @@ -242,40 +186,145 @@ endpoints matching the following regular expressions: ^/_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 + # 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/ -The above endpoints should all be routed to the federation_reader worker by the -reverse-proxy configuration. +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. -The `^/_matrix/federation/v1/send/` endpoint must only be handled by a single -instance. +Registration/login requests can be handled separately purely to help ensure that +unexpected load doesn't affect new logins and sign ups. -Note that `federation` must be added to the listener resources in the worker config: +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 -worker_app: synapse.app.federation_reader -... -worker_listeners: - - type: http - port: <port> - resources: - - names: - - federation +instance_map: + event_persister1: + host: localhost + port: 8034 + +stream_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. -Note this worker cannot be load-balanced: only one instance should be active. +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` @@ -314,46 +363,6 @@ and you must configure a single instance to run the background tasks, e.g.: media_instance_running_background_jobs: "media-repository-1" ``` -### `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 @@ -388,15 +397,48 @@ file. For example: worker_main_http_uri: http://127.0.0.1:8008 -### `synapse.app.event_creator` +### Historical apps -Handles some event creation. It can handle REST endpoints matching: +*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. - ^/_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. +## 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 +``` |