config_documentation.md

Configuring Synapse

This is intended as a guide to the Synapse configuration. The behavior of a Synapse instance can be modified through the many configuration settings documented here — each config option is explained, including what the default is, how to change the default and what sort of behaviour the setting governs. Also included is an example configuration for each setting. If you don't want to spend a lot of time thinking about options, the config as generated sets sensible defaults for all values. Do note however that the database defaults to SQLite, which is not recommended for production usage. You can read more on this subject here.

Config Conventions

Configuration options that take a time period can be set using a number followed by a letter. Letters have the following meanings:

• s = second
• m = minute
• h = hour
• d = day
• w = week
• y = year

For example, setting redaction_retention_period: 5m would remove redacted messages from the database after 5 minutes, rather than 5 months.

In addition, configuration options referring to size use the following suffixes:

• M = MiB, or 1,048,576 bytes
• K = KiB, or 1024 bytes

For example, setting max_avatar_size: 10M means that Synapse will not accept files larger than 10,485,760 bytes for a user avatar.

YAML

The configuration file is a YAML file, which means that certain syntax rules apply if you want your config file to be read properly. A few helpful things to know:

• # before any option in the config will comment out that setting and either a default (if available) will be applied or Synapse will ignore the setting. Thus, in example #1 (closed) below, the setting will be read and applied, but in example #2 (closed) the setting will not be read and a default will be applied.

  Example #1 (closed):

  pid_file: DATADIR/homeserver.pid

  Example #2 (closed):

  #pid_file: DATADIR/homeserver.pid

• Indentation matters! The indentation before a setting will determine whether a given setting is read as part of another setting, or considered on its own. Thus, in example #1 (closed), the enabled setting is read as a sub-option of the presence setting, and will be properly applied.

  However, the lack of indentation before the enabled setting in example #2 (closed) means that when reading the config, Synapse will consider both presence and enabled as different settings. In this case, presence has no value, and thus a default applied, and enabled is an option that Synapse doesn't recognize and thus ignores.

  Example #1 (closed):

  presence:
    enabled: false

  Example #2 (closed):

  presence:
  enabled: false

  In this manual, all top-level settings (ones with no indentation) are identified at the beginning of their section (i.e. "### example_setting") and the sub-options, if any, are identified and listed in the body of the section. In addition, each setting has an example of its usage, with the proper indentation shown.

Modules

Server admins can expand Synapse's functionality with external modules.

See here for more documentation on how to configure or create custom modules for Synapse.

---

modules

Use the module sub-option to add modules under this option to extend functionality. The module setting then has a sub-option, config, which can be used to define some configuration for the module.

Defaults to none.

Example configuration:

modules:
  - module: my_super_module.MySuperClass
    config:
      do_thing: true
  - module: my_other_super_module.SomeClass
    config: {}

---

Server

Define your homeserver name and other base options.

---

server_name

This sets the public-facing domain of the server.

The server_name name will appear at the end of usernames and room addresses created on your server. For example if the server_name was example.com, usernames on your server would be in the format @user:example.com

In most cases you should avoid using a matrix specific subdomain such as matrix.example.com or synapse.example.com as the server_name for the same reasons you wouldn't use user@email.example.com as your email address. See here for information on how to host Synapse on a subdomain while preserving a clean server_name.

The server_name cannot be changed later so it is important to configure this correctly before you start Synapse. It should be all lowercase and may contain an explicit port.

There is no default for this option.

Example configuration #1 (closed):

server_name: matrix.org

Example configuration #2 (closed):

server_name: localhost:8080

---

pid_file

When running Synapse as a daemon, the file to store the pid in. Defaults to none.

Example configuration:

pid_file: DATADIR/homeserver.pid

---

web_client_location

The absolute URL to the web client which / will redirect to. Defaults to none.

Example configuration:

web_client_location: https://riot.example.com/

---

public_baseurl

The public-facing base URL that clients use to access this Homeserver (not including _matrix/...). This is the same URL a user might enter into the 'Custom Homeserver URL' field on their client. If you use Synapse with a reverse proxy, this should be the URL to reach Synapse via the proxy. Otherwise, it should be the URL to reach Synapse's client HTTP listener (see 'listeners' below).

Defaults to https://<server_name>/.

Example configuration:

public_baseurl: https://example.com/

---

serve_server_wellknown

By default, other servers will try to reach our server on port 8448, which can be inconvenient in some environments.

Provided https://<server_name>/ on port 443 is routed to Synapse, this option configures Synapse to serve a file at https://<server_name>/.well-known/matrix/server. This will tell other servers to send traffic to port 443 instead.

This option currently defaults to false.

See https://matrix-org.github.io/synapse/latest/delegate.html for more information.

Example configuration:

serve_server_wellknown: true

---

extra_well_known_client_content

This option allows server runners to add arbitrary key-value pairs to the client-facing .well-known response. Note that the public_baseurl config option must be provided for Synapse to serve a response to /.well-known/matrix/client at all.

If this option is provided, it parses the given yaml to json and serves it on /.well-known/matrix/client endpoint alongside the standard properties.

Added in Synapse 1.62.0.

Example configuration:

extra_well_known_client_content :
  option1: value1
  option2: value2

---

soft_file_limit

Set the soft limit on the number of file descriptors synapse can use. Zero is used to indicate synapse should set the soft limit to the hard limit. Defaults to 0.

Example configuration:

soft_file_limit: 3

---

presence

Presence tracking allows users to see the state (e.g online/offline) of other local and remote users. Set the enabled sub-option to false to disable presence tracking on this homeserver. Defaults to true. This option replaces the previous top-level 'use_presence' option.

Example configuration:

presence:
  enabled: false

---

require_auth_for_profile_requests

Whether to require authentication to retrieve profile data (avatars, display names) of other users through the client API. Defaults to false. Note that profile data is also available via the federation API, unless allow_profile_lookup_over_federation is set to false.

Example configuration:

require_auth_for_profile_requests: true

---

limit_profile_requests_to_users_who_share_rooms

Use this option to require a user to share a room with another user in order to retrieve their profile information. Only checked on Client-Server requests. Profile requests from other servers should be checked by the requesting server. Defaults to false.

Example configuration:

limit_profile_requests_to_users_who_share_rooms: true

---

include_profile_data_on_invite

Use this option to prevent a user's profile data from being retrieved and displayed in a room until they have joined it. By default, a user's profile data is included in an invite event, regardless of the values of the above two settings, and whether or not the users share a server. Defaults to true.

Example configuration:

include_profile_data_on_invite: false

---

allow_public_rooms_without_auth

If set to true, removes the need for authentication to access the server's public rooms directory through the client API, meaning that anyone can query the room directory. Defaults to false.

Example configuration:

allow_public_rooms_without_auth: true

---

allow_public_rooms_over_federation

If set to true, allows any other homeserver to fetch the server's public rooms directory via federation. Defaults to false.

Example configuration:

allow_public_rooms_over_federation: true

---

default_room_version

The default room version for newly created rooms on this server.

Known room versions are listed here

For example, for room version 1, default_room_version should be set to "1".

Currently defaults to "9".

Example configuration:

default_room_version: "8"

---

gc_thresholds

The garbage collection threshold parameters to pass to gc.set_threshold, if defined. Defaults to none.

Example configuration:

gc_thresholds: [700, 10, 10]

---

gc_min_interval

The minimum time in seconds between each GC for a generation, regardless of the GC thresholds. This ensures that we don't do GC too frequently. A value of [1s, 10s, 30s] indicates that a second must pass between consecutive generation 0 GCs, etc.

Defaults to [1s, 10s, 30s].

Example configuration:

gc_min_interval: [0.5s, 30s, 1m]

---

filter_timeline_limit

Set the limit on the returned events in the timeline in the get and sync operations. Defaults to 100. A value of -1 means no upper limit.

Example configuration:

filter_timeline_limit: 5000

---

block_non_admin_invites

Whether room invites to users on this server should be blocked (except those sent by local server admins). Defaults to false.

Example configuration:

block_non_admin_invites: true

---

enable_search

If set to false, new messages will not be indexed for searching and users will receive errors when searching for messages. Defaults to true.

Example configuration:

enable_search: false

---

ip_range_blacklist

This option prevents outgoing requests from being sent to the specified blacklisted IP address CIDR ranges. If this option is not specified then it defaults to private IP address ranges (see the example below).

The blacklist applies to the outbound requests for federation, identity servers, push servers, and for checking key validity for third-party invite events.

(0.0.0.0 and :: are always blacklisted, whether or not they are explicitly listed here, since they correspond to unroutable addresses.)

This option replaces federation_ip_range_blacklist in Synapse v1.25.0.

Note: The value is ignored when an HTTP proxy is in use.

Example configuration:

ip_range_blacklist:
  - '127.0.0.0/8'
  - '10.0.0.0/8'
  - '172.16.0.0/12'
  - '192.168.0.0/16'
  - '100.64.0.0/10'
  - '192.0.0.0/24'
  - '169.254.0.0/16'
  - '192.88.99.0/24'
  - '198.18.0.0/15'
  - '192.0.2.0/24'
  - '198.51.100.0/24'
  - '203.0.113.0/24'
  - '224.0.0.0/4'
  - '::1/128'
  - 'fe80::/10'
  - 'fc00::/7'
  - '2001:db8::/32'
  - 'ff00::/8'
  - 'fec0::/10'

---

ip_range_whitelist

List of IP address CIDR ranges that should be allowed for federation, identity servers, push servers, and for checking key validity for third-party invite events. This is useful for specifying exceptions to wide-ranging blacklisted target IP ranges - e.g. for communication with a push server only visible in your network.

This whitelist overrides ip_range_blacklist and defaults to an empty list.

Example configuration:

ip_range_whitelist:
   - '192.168.1.1'

---

listeners

List of ports that Synapse should listen on, their purpose and their configuration.

Sub-options for each listener include:

• port: the TCP port to bind to.

• bind_addresses: a list of local addresses to listen on. The default is 'all local interfaces'.

• type: the type of listener. Normally http, but other valid options are:

  • manhole: (see the docs here),

  • metrics: (see the docs here),

  • replication: (deprecated as of Synapse 1.18, see the docs here).

• tls: set to true to enable TLS for this listener. Will use the TLS key/cert specified in tls_private_key_path / tls_certificate_path.

• x_forwarded: Only valid for an 'http' listener. Set to true to use the X-Forwarded-For header as the client IP. Useful when Synapse is behind a reverse-proxy.

• resources: Only valid for an 'http' listener. A list of resources to host on this port. Sub-options for each resource are:

  • names: a list of names of HTTP resources. See below for a list of valid resource names.

  • compress: set to true to enable gzip compression on HTTP bodies for this resource. This is currently only supported with the client, consent, metrics and federation resources.

• additional_resources: Only valid for an 'http' listener. A map of additional endpoints which should be loaded via dynamic modules.

Valid resource names are:

• client: the client-server API (/_matrix/client), and the synapse admin API (/_synapse/admin). Also implies media and static.

• consent: user consent forms (/_matrix/consent). See here for more.

• federation: the server-server API (/_matrix/federation). Also implies media, keys, openid

• keys: the key discovery API (/_matrix/key).

• media: the media API (/_matrix/media).

• metrics: the metrics interface. See here.

• openid: OpenID authentication. See here.

• replication: the HTTP replication API (/_synapse/replication). See here.

• static: static resources under synapse/static (/_matrix/static). (Mostly useful for 'fallback authentication'.)

Example configuration #1 (closed):

listeners:
  # TLS-enabled listener: for when matrix traffic is sent directly to synapse.
  #
  # (Note that you will also need to give Synapse a TLS key and certificate: see the TLS section
  # below.)
  #
  - port: 8448
    type: http
    tls: true
    resources:
      - names: [client, federation]

Example configuration #2 (closed):

listeners:
  # Unsecure HTTP listener: for when matrix traffic passes through a reverse proxy
  # that unwraps TLS.
  #
  # If you plan to use a reverse proxy, please see
  # https://matrix-org.github.io/synapse/latest/reverse_proxy.html.
  #
  - port: 8008
    tls: false
    type: http
    x_forwarded: true
    bind_addresses: ['::1', '127.0.0.1']

    resources:
      - names: [client, federation]
        compress: false

    # example additional_resources:
    additional_resources:
      "/_matrix/my/custom/endpoint":
        module: my_module.CustomRequestHandler
        config: {}

  # Turn on the twisted ssh manhole service on localhost on the given
  # port.
  - port: 9000
    bind_addresses: ['::1', '127.0.0.1']
    type: manhole

---

manhole_settings

Connection settings for the manhole. You can find more information on the manhole here. Manhole sub-options include:

• username : the username for the manhole. This defaults to 'matrix'.
• password: The password for the manhole. This defaults to 'rabbithole'.
• ssh_priv_key_path and ssh_pub_key_path: The private and public SSH key pair used to encrypt the manhole traffic. If these are left unset, then hardcoded and non-secret keys are used, which could allow traffic to be intercepted if sent over a public network.

Example configuration:

manhole_settings:
  username: manhole
  password: mypassword
  ssh_priv_key_path: CONFDIR/id_rsa
  ssh_pub_key_path: CONFDIR/id_rsa.pub

---

dummy_events_threshold

Forward extremities can build up in a room due to networking delays between homeservers. Once this happens in a large room, calculation of the state of that room can become quite expensive. To mitigate this, once the number of forward extremities reaches a given threshold, Synapse will send an org.matrix.dummy_event event, which will reduce the forward extremities in the room.

This setting defines the threshold (i.e. number of forward extremities in the room) at which dummy events are sent. The default value is 10.

Example configuration:

dummy_events_threshold: 5

---

delete_stale_devices_after

An optional duration. If set, Synapse will run a daily background task to log out and delete any device that hasn't been accessed for more than the specified amount of time.

Defaults to no duration, which means devices are never pruned.

Example configuration:

delete_stale_devices_after: 1y

Homeserver blocking