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 Delegation of incoming federation traffic 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),

• 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.

• request_id_header: The header extracted from each incoming request that is used as the basis for the request ID. The request ID is used in logs and tracing to correlate and match up requests. When unset, Synapse will automatically generate sequential request IDs. This option is useful when Synapse is behind a reverse-proxy.

  Added in Synapse 1.68.0.

• 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

---

email

Configuration for sending emails from Synapse.

Server admins can configure custom templates for email content. See here for more information.

This setting has the following sub-options:

• smtp_host: The hostname of the outgoing SMTP server to use. Defaults to 'localhost'.

• smtp_port: The port on the mail server for outgoing SMTP. Defaults to 465 if force_tls is true, else 25.

  Changed in Synapse 1.64.0: the default port is now aware of force_tls.

• smtp_user and smtp_pass: Username/password for authentication to the SMTP server. By default, no authentication is attempted.

• force_tls: By default, Synapse connects over plain text and then optionally upgrades to TLS via STARTTLS. If this option is set to true, TLS is used from the start (Implicit TLS), and the option require_transport_security is ignored. It is recommended to enable this if supported by your mail server.

  New in Synapse 1.64.0.

• require_transport_security: Set to true to require TLS transport security for SMTP. By default, Synapse will connect over plain text, and will then switch to TLS via STARTTLS if the SMTP server supports it. If this option is set, Synapse will refuse to connect unless the server supports STARTTLS.

• enable_tls: By default, if the server supports TLS, it will be used, and the server must present a certificate that is valid for 'smtp_host'. If this option is set to false, TLS will not be used.

• notif_from: defines the "From" address to use when sending emails. It must be set if email sending is enabled. The placeholder '%(app)s' will be replaced by the application name, which is normally set in app_name, but may be overridden by the Matrix client application. Note that the placeholder must be written '%(app)s', including the trailing 's'.

• app_name: app_name defines the default value for '%(app)s' in notif_from and email subjects. It defaults to 'Matrix'.

• enable_notifs: Set to true to enable sending emails for messages that the user has missed. Disabled by default.

• notif_for_new_users: Set to false to disable automatic subscription to email notifications for new users. Enabled by default.

• client_base_url: Custom URL for client links within the email notifications. By default links will be based on "https://matrix.to". (This setting used to be called riot_base_url; the old name is still supported for backwards-compatibility but is now deprecated.)

• validation_token_lifetime: Configures the time that a validation email will expire after sending. Defaults to 1h.

• invite_client_location: The web client location to direct users to during an invite. This is passed to the identity server as the org.matrix.web_client_location key. Defaults to unset, giving no guidance to the identity server.

• subjects: Subjects to use when sending emails from Synapse. The placeholder '%(app)s' will be replaced with the value of the app_name setting, or by a value dictated by the Matrix client application. In addition, each subject can use the following placeholders: '%(person)s', which will be replaced by the displayname of the user(s) that sent the message(s), e.g. "Alice and Bob", and '%(room)s', which will be replaced by the name of the room the message(s) have been sent to, e.g. "My super room". In addition, emails related to account administration will can use the '%(server_name)s' placeholder, which will be replaced by the value of the server_name setting in your Synapse configuration.

  Here is a list of subjects for notification emails that can be set:

  • message_from_person_in_room: Subject to use to notify about one message from one or more user(s) in a room which has a name. Defaults to "[%(app)s] You have a message on %(app)s from %(person)s in the %(room)s room..."
  • message_from_person: Subject to use to notify about one message from one or more user(s) in a room which doesn't have a name. Defaults to "[%(app)s] You have a message on %(app)s from %(person)s..."
  • messages_from_person: Subject to use to notify about multiple messages from one or more users in a room which doesn't have a name. Defaults to "[%(app)s] You have messages on %(app)s from %(person)s..."
  • messages_in_room: Subject to use to notify about multiple messages in a room which has a name. Defaults to "[%(app)s] You have messages on %(app)s in the %(room)s room..."
  • messages_in_room_and_others: Subject to use to notify about multiple messages in multiple rooms. Defaults to "[%(app)s] You have messages on %(app)s in the %(room)s room and others..."
  • messages_from_person_and_others: Subject to use to notify about multiple messages from multiple persons in multiple rooms. This is similar to the setting above except it's used when the room in which the notification was triggered has no name. Defaults to "[%(app)s] You have messages on %(app)s from %(person)s and others..."
  • invite_from_person_to_room: Subject to use to notify about an invite to a room which has a name. Defaults to "[%(app)s] %(person)s has invited you to join the %(room)s room on %(app)s..."
  • invite_from_person: Subject to use to notify about an invite to a room which doesn't have a name. Defaults to "[%(app)s] %(person)s has invited you to chat on %(app)s..."
  • password_reset: Subject to use when sending a password reset email. Defaults to "[%(server_name)s] Password reset"
  • email_validation: Subject to use when sending a verification email to assert an address's ownership. Defaults to "[%(server_name)s] Validate your email"

Example configuration:

email:
  smtp_host: mail.server
  smtp_port: 587
  smtp_user: "exampleusername"
  smtp_pass: "examplepassword"
  force_tls: true
  require_transport_security: true
  enable_tls: false
  notif_from: "Your Friendly %(app)s homeserver <noreply@example.com>"
  app_name: my_branded_matrix_server
  enable_notifs: true
  notif_for_new_users: false
  client_base_url: "http://localhost/riot"
  validation_token_lifetime: 15m
  invite_client_location: https://app.element.io

  subjects:
    message_from_person_in_room: "[%(app)s] You have a message on %(app)s from %(person)s in the %(room)s room..."
    message_from_person: "[%(app)s] You have a message on %(app)s from %(person)s..."
    messages_from_person: "[%(app)s] You have messages on %(app)s from %(person)s..."
    messages_in_room: "[%(app)s] You have messages on %(app)s in the %(room)s room..."
    messages_in_room_and_others: "[%(app)s] You have messages on %(app)s in the %(room)s room and others..."
    messages_from_person_and_others: "[%(app)s] You have messages on %(app)s from %(person)s and others..."
    invite_from_person_to_room: "[%(app)s] %(person)s has invited you to join the %(room)s room on %(app)s..."
    invite_from_person: "[%(app)s] %(person)s has invited you to chat on %(app)s..."
    password_reset: "[%(server_name)s] Password reset"
    email_validation: "[%(server_name)s] Validate your email"

Homeserver blocking

Useful options for Synapse admins.

---

admin_contact

How to reach the server admin, used in ResourceLimitError. Defaults to none.

Example configuration:

admin_contact: 'mailto:admin@server.com'

---

hs_disabled and hs_disabled_message

Blocks users from connecting to the homeserver and provides a human-readable reason why the connection was blocked. Defaults to false.

Example configuration:

hs_disabled: true
hs_disabled_message: 'Reason for why the HS is blocked'

---

limit_usage_by_mau

This option disables/enables monthly active user blocking. Used in cases where the admin or server owner wants to limit to the number of monthly active users. When enabled and a limit is reached the server returns a ResourceLimitError with error type Codes.RESOURCE_LIMIT_EXCEEDED. Defaults to false. If this is enabled, a value for max_mau_value must also be set.

See Monthly Active Users for details on how to configure MAU.

Example configuration:

limit_usage_by_mau: true

---

max_mau_value

This option sets the hard limit of monthly active users above which the server will start blocking user actions if limit_usage_by_mau is enabled. Defaults to 0.

Example configuration:

max_mau_value: 50

---

mau_trial_days

The option mau_trial_days is a means to add a grace period for active users. It means that users must be active for the specified number of days before they can be considered active and guards against the case where lots of users sign up in a short space of time never to return after their initial session. Defaults to 0.

Example configuration:

mau_trial_days: 5

---

mau_appservice_trial_days

The option mau_appservice_trial_days is similar to mau_trial_days, but applies a different trial number if the user was registered by an appservice. A value of 0 means no trial days are applied. Appservices not listed in this dictionary use the value of mau_trial_days instead.

Example configuration:

mau_appservice_trial_days:
  my_appservice_id: 3
  another_appservice_id: 6

---

mau_limit_alerting

The option mau_limit_alerting is a means of limiting client-side alerting should the mau limit be reached. This is useful for small instances where the admin has 5 mau seats (say) for 5 specific people and no interest increasing the mau limit further. Defaults to true, which means that alerting is enabled.

Example configuration:

mau_limit_alerting: false

---

mau_stats_only

If enabled, the metrics for the number of monthly active users will be populated, however no one will be limited based on these numbers. If limit_usage_by_mau is true, this is implied to be true. Defaults to false.

Example configuration:

mau_stats_only: true

---

mau_limit_reserved_threepids

Sometimes the server admin will want to ensure certain accounts are never blocked by mau checking. These accounts are specified by this option. Defaults to none. Add accounts by specifying the medium and address of the reserved threepid (3rd party identifier).

Example configuration:

mau_limit_reserved_threepids:
  - medium: 'email'
    address: 'reserved_user@example.com'

---

server_context

This option is used by phonehome stats to group together related servers. Defaults to none.

Example configuration:

server_context: context

---

limit_remote_rooms

When this option is enabled, the room "complexity" will be checked before a user joins a new remote room. If it is above the complexity limit, the server will disallow joining, or will instantly leave. This is useful for homeservers that are resource-constrained. Options for this setting include:

• enabled: whether this check is enabled. Defaults to false.
• complexity: the limit above which rooms cannot be joined. The default is 1.0.
• complexity_error: override the error which is returned when the room is too complex with a custom message.
• admins_can_join: allow server admins to join complex rooms. Default is false.

Room complexity is an arbitrary measure based on factors such as the number of users in the room.

Example configuration:

limit_remote_rooms:
  enabled: true
  complexity: 0.5
  complexity_error: "I can't let you do that, Dave."
  admins_can_join: true

---

require_membership_for_aliases

Whether to require a user to be in the room to add an alias to it. Defaults to true.

Example configuration:

require_membership_for_aliases: false

---

allow_per_room_profiles

Whether to allow per-room membership profiles through the sending of membership events with profile information that differs from the target's global profile. Defaults to true.

Example configuration:

allow_per_room_profiles: false

---

max_avatar_size

The largest permissible file size in bytes for a user avatar. Defaults to no restriction. Use M for MB and K for KB.

Note that user avatar changes will not work if this is set without using Synapse's media repository.

Example configuration:

max_avatar_size: 10M

---

allowed_avatar_mimetypes

The MIME types allowed for user avatars. Defaults to no restriction.

Note that user avatar changes will not work if this is set without using Synapse's media repository.

Example configuration:

allowed_avatar_mimetypes: ["image/png", "image/jpeg", "image/gif"]

---

redaction_retention_period

How long to keep redacted events in unredacted form in the database. After this period redacted events get replaced with their redacted form in the DB.

Synapse will check whether the rentention period has concluded for redacted events every 5 minutes. Thus, even if this option is set to 0, Synapse may still take up to 5 minutes to purge redacted events from the database.

Defaults to 7d. Set to null to disable.

Example configuration:

redaction_retention_period: 28d

---

user_ips_max_age

How long to track users' last seen time and IPs in the database.

Defaults to 28d. Set to null to disable clearing out of old rows.

Example configuration:

user_ips_max_age: 14d

---

request_token_inhibit_3pid_errors

Inhibits the /requestToken endpoints from returning an error that might leak information about whether an e-mail address is in use or not on this homeserver. Defaults to false. Note that for some endpoints the error situation is the e-mail already being used, and for others the error is entering the e-mail being unused. If this option is enabled, instead of returning an error, these endpoints will act as if no error happened and return a fake session ID ('sid') to clients.

Example configuration:

request_token_inhibit_3pid_errors: true

---

next_link_domain_whitelist

A list of domains that the domain portion of next_link parameters must match.

This parameter is optionally provided by clients while requesting validation of an email or phone number, and maps to a link that users will be automatically redirected to after validation succeeds. Clients can make use this parameter to aid the validation process.

The whitelist is applied whether the homeserver or an identity server is handling validation.

The default value is no whitelist functionality; all domains are allowed. Setting this value to an empty list will instead disallow all domains.

Example configuration:

next_link_domain_whitelist: ["matrix.org"]

---

templates and custom_template_directory

These options define templates to use when generating email or HTML page contents. The custom_template_directory determines which directory Synapse will try to find template files in to use to generate email or HTML page contents. If not set, or a file is not found within the template directory, a default template from within the Synapse package will be used.

See here for more information about using custom templates.

Example configuration:

templates:
  custom_template_directory: /path/to/custom/templates/

---

retention

This option and the associated options determine message retention policy at the server level.

Room admins and mods can define a retention period for their rooms using the m.room.retention state event, and server admins can cap this period by setting the allowed_lifetime_min and allowed_lifetime_max config options.

If this feature is enabled, Synapse will regularly look for and purge events which are older than the room's maximum retention period. Synapse will also filter events received over federation so that events that should have been purged are ignored and not stored again.

The message retention policies feature is disabled by default. Please be advised that enabling this feature carries some risk. There are known bugs with the implementation which can cause database corruption. Setting retention to delete older history is less risky than deleting newer history but in general caution is advised when enabling this experimental feature. You can read more about this feature here.

This setting has the following sub-options:

• default_policy: Default retention policy. If set, Synapse will apply it to rooms that lack the 'm.room.retention' state event. This option is further specified by the min_lifetime and max_lifetime sub-options associated with it. Note that the value of min_lifetime doesn't matter much because Synapse doesn't take it into account yet.

• allowed_lifetime_min and allowed_lifetime_max: Retention policy limits. If set, and the state of a room contains a m.room.retention event in its state which contains a min_lifetime or a max_lifetime that's out of these bounds, Synapse will cap the room's policy to these limits when running purge jobs.

• purge_jobs and the associated shortest_max_lifetime and longest_max_lifetime sub-options: Server admins can define the settings of the background jobs purging the events whose lifetime has expired under the purge_jobs section.

  If no configuration is provided for this option, a single job will be set up to delete expired events in every room daily.

  Each job's configuration defines which range of message lifetimes the job takes care of. For example, if shortest_max_lifetime is '2d' and longest_max_lifetime is '3d', the job will handle purging expired events in rooms whose state defines a max_lifetime that's both higher than 2 days, and lower than or equal to 3 days. Both the minimum and the maximum value of a range are optional, e.g. a job with no shortest_max_lifetime and a longest_max_lifetime of '3d' will handle every room with a retention policy whose max_lifetime is lower than or equal to three days.

  The rationale for this per-job configuration is that some rooms might have a retention policy with a low max_lifetime, where history needs to be purged of outdated messages on a more frequent basis than for the rest of the rooms (e.g. every 12h), but not want that purge to be performed by a job that's iterating over every room it knows, which could be heavy on the server.

  If any purge job is configured, it is strongly recommended to have at least a single job with neither shortest_max_lifetime nor longest_max_lifetime set, or one job without shortest_max_lifetime and one job without longest_max_lifetime set. Otherwise some rooms might be ignored, even if allowed_lifetime_min and allowed_lifetime_max are set, because capping a room's policy to these values is done after the policies are retrieved from Synapse's database (which is done using the range specified in a purge job's configuration).

Example configuration:

retention:
  enabled: true
  default_policy:
    min_lifetime: 1d
    max_lifetime: 1y
  allowed_lifetime_min: 1d
  allowed_lifetime_max: 1y
  purge_jobs:
    - longest_max_lifetime: 3d
      interval: 12h
    - shortest_max_lifetime: 3d
      interval: 1d

---

TLS

Options related to TLS.

---

tls_certificate_path

This option specifies a PEM-encoded X509 certificate for TLS. This certificate, as of Synapse 1.0, will need to be a valid and verifiable certificate, signed by a recognised Certificate Authority. Defaults to none.

Be sure to use a .pem file that includes the full certificate chain including any intermediate certificates (for instance, if using certbot, use fullchain.pem as your certificate, not cert.pem).

Example configuration:

tls_certificate_path: "CONFDIR/SERVERNAME.tls.crt"

---

tls_private_key_path

PEM-encoded private key for TLS. Defaults to none.

Example configuration:

tls_private_key_path: "CONFDIR/SERVERNAME.tls.key"

---

federation_verify_certificates

Whether to verify TLS server certificates for outbound federation requests.

Defaults to true. To disable certificate verification, set the option to false.

Example configuration:

federation_verify_certificates: false

---

federation_client_minimum_tls_version

The minimum TLS version that will be used for outbound federation requests.

Defaults to 1. Configurable to 1, 1.1, 1.2, or 1.3. Note that setting this value higher than 1.2 will prevent federation to most of the public Matrix network: only configure it to 1.3 if you have an entirely private federation setup and you can ensure TLS 1.3 support.

Example configuration:

federation_client_minimum_tls_version: 1.2

---

federation_certificate_verification_whitelist

Skip federation certificate verification on a given whitelist of domains.

This setting should only be used in very specific cases, such as federation over Tor hidden services and similar. For private networks of homeservers, you likely want to use a private CA instead.

Only effective if federation_verify_certicates is true.

Example configuration:

federation_certificate_verification_whitelist:
  - lon.example.com
  - "*.domain.com"
  - "*.onion"

---

federation_custom_ca_list

List of custom certificate authorities for federation traffic.

This setting should only normally be used within a private network of homeservers.

Note that this list will replace those that are provided by your operating environment. Certificates must be in PEM format.

Example configuration:

federation_custom_ca_list:
  - myCA1.pem
  - myCA2.pem
  - myCA3.pem

---

Federation

Options related to federation.

---

federation_domain_whitelist

Restrict federation to the given whitelist of domains. N.B. we recommend also firewalling your federation listener to limit inbound federation traffic as early as possible, rather than relying purely on this application-layer restriction. If not specified, the default is to whitelist everything.

Example configuration:

federation_domain_whitelist:
  - lon.example.com
  - nyc.example.com
  - syd.example.com

---

federation_metrics_domains

Report prometheus metrics on the age of PDUs being sent to and received from the given domains. This can be used to give an idea of "delay" on inbound and outbound federation, though be aware that any delay can be due to problems at either end or with the intermediate network.

By default, no domains are monitored in this way.

Example configuration:

federation_metrics_domains:
  - matrix.org
  - example.com

---

allow_profile_lookup_over_federation

Set to false to disable profile lookup over federation. By default, the Federation API allows other homeservers to obtain profile data of any user on this homeserver.

Example configuration:

allow_profile_lookup_over_federation: false

---

allow_device_name_lookup_over_federation

Set this option to true to allow device display name lookup over federation. By default, the Federation API prevents other homeservers from obtaining the display names of any user devices on this homeserver.

Example configuration:

allow_device_name_lookup_over_federation: true

---

Caching

Options related to caching.

---

event_cache_size

The number of events to cache in memory. Defaults to 10K. Like other caches, this is affected by caches.global_factor (see below).

Note that this option is not part of the caches section.

Example configuration:

event_cache_size: 15K

---

caches and associated values

A cache 'factor' is a multiplier that can be applied to each of Synapse's caches in order to increase or decrease the maximum number of entries that can be stored.

caches can be configured through the following sub-options:

• global_factor: Controls the global cache factor, which is the default cache factor for all caches if a specific factor for that cache is not otherwise set.

  This can also be set by the SYNAPSE_CACHE_FACTOR environment variable. Setting by environment variable takes priority over setting through the config file.

  Defaults to 0.5, which will halve the size of all caches.

• per_cache_factors: A dictionary of cache name to cache factor for that individual cache. Overrides the global cache factor for a given cache.

  These can also be set through environment variables comprised of SYNAPSE_CACHE_FACTOR_ + the name of the cache in capital letters and underscores. Setting by environment variable takes priority over setting through the config file. Ex. SYNAPSE_CACHE_FACTOR_GET_USERS_WHO_SHARE_ROOM_WITH_USER=2.0

  Some caches have '*' and other characters that are not alphanumeric or underscores. These caches can be named with or without the special characters stripped. For example, to specify the cache factor for *stateGroupCache* via an environment variable would be SYNAPSE_CACHE_FACTOR_STATEGROUPCACHE=2.0.

• expire_caches: Controls whether cache entries are evicted after a specified time period. Defaults to true. Set to false to disable this feature. Note that never expiring caches may result in excessive memory usage.

• cache_entry_ttl: If expire_caches is enabled, this flag controls how long an entry can be in a cache without having been accessed before being evicted. Defaults to 30m.

• sync_response_cache_duration: Controls how long the results of a /sync request are cached for after a successful response is returned. A higher duration can help clients with intermittent connections, at the cost of higher memory usage. A value of zero means that sync responses are not cached. Defaults to 2m.

  Changed in Synapse 1.62.0: The default was changed from 0 to 2m.

• cache_autotuning and its sub-options max_cache_memory_usage, target_cache_memory_usage, and min_cache_ttl work in conjunction with each other to maintain a balance between cache memory usage and cache entry availability. You must be using jemalloc to utilize this option, and all three of the options must be specified for this feature to work. This option defaults to off, enable it by providing values for the sub-options listed below. Please note that the feature will not work and may cause unstable behavior (such as excessive emptying of caches or exceptions) if all of the values are not provided. Please see the Config Conventions for information on how to specify memory size and cache expiry durations.

  • max_cache_memory_usage sets a ceiling on how much memory the cache can use before caches begin to be continuously evicted. They will continue to be evicted until the memory usage drops below the target_memory_usage, set in the setting below, or until the min_cache_ttl is hit. There is no default value for this option.
  • target_cache_memory_usage sets a rough target for the desired memory usage of the caches. There is no default value for this option.
  • min_cache_ttl sets a limit under which newer cache entries are not evicted and is only applied when caches are actively being evicted/max_cache_memory_usage has been exceeded. This is to protect hot caches from being emptied while Synapse is evicting due to memory. There is no default value for this option.

Example configuration:

event_cache_size: 15K
caches:
  global_factor: 1.0
  per_cache_factors:
    get_users_who_share_room_with_user: 2.0
  sync_response_cache_duration: 2m
  cache_autotuning:
    max_cache_memory_usage: 1024M
    target_cache_memory_usage: 758M
    min_cache_ttl: 5m

Reloading cache factors

The cache factors (i.e. caches.global_factor and caches.per_cache_factors) may be reloaded at any time by sending a SIGHUP signal to Synapse using e.g.

kill -HUP [PID_OF_SYNAPSE_PROCESS]

If you are running multiple workers, you must individually update the worker config file and send this signal to each worker process.

If you're using the example systemd service file in Synapse's contrib directory, you can send a SIGHUP signal by using systemctl reload matrix-synapse.

---

Database

Config options related to database settings.

---

database

The database setting defines the database that synapse uses to store all of its data.

Associated sub-options:

• name: this option specifies the database engine to use: either sqlite3 (for SQLite) or psycopg2 (for PostgreSQL). If no name is specified Synapse will default to SQLite.

• txn_limit gives the maximum number of transactions to run per connection before reconnecting. Defaults to 0, which means no limit.

• allow_unsafe_locale is an option specific to Postgres. Under the default behavior, Synapse will refuse to start if the postgres db is set to a non-C locale. You can override this behavior (which is not recommended) by setting allow_unsafe_locale to true. Note that doing so may corrupt your database. You can find more information here and here.

• args gives options which are passed through to the database engine, except for options starting with cp_, which are used to configure the Twisted connection pool. For a reference to valid arguments, see:

  • for sqlite
  • for postgres
  • for the connection pool

For more information on using Synapse with Postgres, see here.

Example SQLite configuration:

database:
  name: sqlite3
  args:
    database: /path/to/homeserver.db

Example Postgres configuration:

database:
  name: psycopg2
  txn_limit: 10000
  args:
    user: synapse_user
    password: secretpassword
    database: synapse
    host: localhost
    port: 5432
    cp_min: 5
    cp_max: 10

---

databases

The databases option allows specifying a mapping between certain database tables and database host details, spreading the load of a single Synapse instance across multiple database backends. This is often referred to as "database sharding". This option is only supported for PostgreSQL database backends.

Important note: This is a supported option, but is not currently used in production by the Matrix.org Foundation. Proceed with caution and always make backups.

databases is a dictionary of arbitrarily-named database entries. Each entry is equivalent to the value of the database homeserver config option (see above), with the addition of a data_stores key. data_stores is an array of strings that specifies the data store(s) (a defined label for a set of tables) that should be stored on the associated database backend entry.

The currently defined values for data_stores are:

• "state": Database that relates to state groups will be stored in this database.

  Specifically, that means the following tables:

  • state_groups
  • state_group_edges
  • state_groups_state

  And the following sequences:

  • state_groups_seq_id

• "main": All other database tables and sequences.

All databases will end up with additional tables used for tracking database schema migrations and any pending background updates. Synapse will create these automatically on startup when checking for and/or performing database schema migrations.

To migrate an existing database configuration (e.g. all tables on a single database) to a different configuration (e.g. the "main" data store on one database, and "state" on another), do the following:

1. Take a backup of your existing database. Things can and do go wrong and database corruption is no joke!

2. Ensure all pending database migrations have been applied and background updates have run. The simplest way to do this is to use the update_synapse_database script supplied with your Synapse installation.

   update_synapse_database --database-config homeserver.yaml --run-background-updates

3. Copy over the necessary tables and sequences from one database to the other. Tables relating to database migrations, schemas, schema versions and background updates should not be copied.

   As an example, say that you'd like to split out the "state" data store from an existing database which currently contains all data stores.

   Simply copy the tables and sequences defined above for the "state" datastore from the existing database to the secondary database. As noted above, additional tables will be created in the secondary database when Synapse is started.

4. Modify/create the databases option in your homeserver.yaml to match the desired database configuration.

5. Start Synapse. Check that it starts up successfully and that things generally seem to be working.

6. Drop the old tables that were copied in step 3.

Only one of the options database or databases may be specified in your config, but not both.

Example configuration:

databases:
  basement_box:
    name: psycopg2
    txn_limit: 10000
    data_stores: ["main"]
    args:
      user: synapse_user
      password: secretpassword
      database: synapse_main
      host: localhost
      port: 5432
      cp_min: 5
      cp_max: 10

  my_other_database:
    name: psycopg2
    txn_limit: 10000
    data_stores: ["state"]
    args:
      user: synapse_user
      password: secretpassword
      database: synapse_state
      host: localhost
      port: 5432
      cp_min: 5
      cp_max: 10

---

Logging

Config options related to logging.

---

log_config

This option specifies a yaml python logging config file as described here.

Example configuration:

log_config: "CONFDIR/SERVERNAME.log.config"

---

Ratelimiting

Options related to ratelimiting in Synapse.

Each ratelimiting configuration is made of two parameters:

• per_second: number of requests a client can send per second.
• burst_count: number of requests a client can send before being throttled.

---

rc_message

Ratelimiting settings for client messaging.

This is a ratelimiting option for messages that ratelimits sending based on the account the client is using. It defaults to: per_second: 0.2, burst_count: 10.

Example configuration:

rc_message:
  per_second: 0.5
  burst_count: 15

---

rc_registration

This option ratelimits registration requests based on the client's IP address. It defaults to per_second: 0.17, burst_count: 3.

Example configuration:

rc_registration:
  per_second: 0.15
  burst_count: 2

---

rc_registration_token_validity

This option checks the validity of registration tokens that ratelimits requests based on the client's IP address. Defaults to per_second: 0.1, burst_count: 5.

Example configuration:

rc_registration_token_validity:
  per_second: 0.3
  burst_count: 6

---

rc_login

This option specifies several limits for login:

• address ratelimits login requests based on the client's IP address. Defaults to per_second: 0.17, burst_count: 3.

• account ratelimits login requests based on the account the client is attempting to log into. Defaults to per_second: 0.17, burst_count: 3.

• failed_attempts ratelimits login requests based on the account the client is attempting to log into, based on the amount of failed login attempts for this account. Defaults to per_second: 0.17, burst_count: 3.

Example configuration:

rc_login:
  address:
    per_second: 0.15
    burst_count: 5
  account:
    per_second: 0.18
    burst_count: 4
  failed_attempts:
    per_second: 0.19
    burst_count: 7

---

rc_admin_redaction

This option sets ratelimiting redactions by room admins. If this is not explicitly set then it uses the same ratelimiting as per rc_message. This is useful to allow room admins to deal with abuse quickly.

Example configuration:

rc_admin_redaction:
  per_second: 1
  burst_count: 50

---

rc_joins

This option allows for ratelimiting number of rooms a user can join. This setting has the following sub-options:

• local: ratelimits when users are joining rooms the server is already in. Defaults to per_second: 0.1, burst_count: 10.

• remote: ratelimits when users are trying to join rooms not on the server (which can be more computationally expensive than restricting locally). Defaults to per_second: 0.01, burst_count: 10

Example configuration:

rc_joins:
  local:
    per_second: 0.2
    burst_count: 15
  remote:
    per_second: 0.03
    burst_count: 12

---

rc_joins_per_room

This option allows admins to ratelimit joins to a room based on the number of recent joins (local or remote) to that room. It is intended to mitigate mass-join spam waves which target multiple homeservers.

By default, one join is permitted to a room every second, with an accumulating buffer of up to ten instantaneous joins.

Example configuration (default values):

rc_joins_per_room:
  per_second: 1
  burst_count: 10

Added in Synapse 1.64.0.

---

rc_3pid_validation

This option ratelimits how often a user or IP can attempt to validate a 3PID. Defaults to per_second: 0.003, burst_count: 5.

Example configuration:

rc_3pid_validation:
  per_second: 0.003
  burst_count: 5

---

rc_invites

This option sets ratelimiting how often invites can be sent in a room or to a specific user. per_room defaults to per_second: 0.3, burst_count: 10 and per_user defaults to per_second: 0.003, burst_count: 5.

Client requests that invite user(s) when creating a room will count against the rc_invites.per_room limit, whereas client requests to invite a single user to a room will count against both the rc_invites.per_user and rc_invites.per_room limits.

Federation requests to invite a user will count against the rc_invites.per_user limit only, as Synapse presumes ratelimiting by room will be done by the sending server.

The rc_invites.per_user limit applies to the receiver of the invite, rather than the sender, meaning that a rc_invite.per_user.burst_count of 5 mandates that a single user cannot receive more than a burst of 5 invites at a time.

In contrast, the rc_invites.per_issuer limit applies to the issuer of the invite, meaning that a rc_invite.per_issuer.burst_count of 5 mandates that single user cannot send more than a burst of 5 invites at a time.

Changed in version 1.63: added the per_issuer limit.

Example configuration:

rc_invites:
  per_room:
    per_second: 0.5
    burst_count: 5
  per_user:
    per_second: 0.004
    burst_count: 3
  per_issuer:
    per_second: 0.5
    burst_count: 5

---

rc_third_party_invite

This option ratelimits 3PID invites (i.e. invites sent to a third-party ID such as an email address or a phone number) based on the account that's sending the invite. Defaults to per_second: 0.2, burst_count: 10.

Example configuration:

rc_third_party_invite:
  per_second: 0.2
  burst_count: 10

---

rc_federation

Defines limits on federation requests.

The rc_federation configuration has the following sub-options:

• window_size: window size in milliseconds. Defaults to 1000.
• sleep_limit: number of federation requests from a single server in a window before the server will delay processing the request. Defaults to 10.
• sleep_delay: duration in milliseconds to delay processing events from remote servers by if they go over the sleep limit. Defaults to 500.
• reject_limit: maximum number of concurrent federation requests allowed from a single server. Defaults to 50.
• concurrent: number of federation requests to concurrently process from a single server. Defaults to 3.

Example configuration:

rc_federation:
  window_size: 750
  sleep_limit: 15
  sleep_delay: 400
  reject_limit: 40
  concurrent: 5

---

federation_rr_transactions_per_room_per_second

Sets outgoing federation transaction frequency for sending read-receipts, per-room.

If we end up trying to send out more read-receipts, they will get buffered up into fewer transactions. Defaults to 50.

Example configuration:

federation_rr_transactions_per_room_per_second: 40

---

Media Store

Config options related to Synapse's media store.

---

enable_media_repo

Enable the media store service in the Synapse master. Defaults to true. Set to false if you are using a separate media store worker.

Example configuration:

enable_media_repo: false

---

media_store_path

Directory where uploaded images and attachments are stored.

Example configuration:

media_store_path: "DATADIR/media_store"

---

media_storage_providers

Media storage providers allow media to be stored in different locations. Defaults to none. Associated sub-options are:

• module: type of resource, e.g. file_system.
• store_local: whether to store newly uploaded local files
• store_remote: whether to store newly downloaded local files
• store_synchronous: whether to wait for successful storage for local uploads
• config: sets a path to the resource through the directory option

Example configuration:

media_storage_providers:
  - module: file_system
    store_local: false
    store_remote: false
    store_synchronous: false
    config:
       directory: /mnt/some/other/directory

---

max_upload_size

The largest allowed upload size in bytes.

If you are using a reverse proxy you may also need to set this value in your reverse proxy's config. Defaults to 50M. Notably Nginx has a small max body size by default. See here for more on using a reverse proxy with Synapse.

Example configuration:

max_upload_size: 60M

---

max_image_pixels

Maximum number of pixels that will be thumbnailed. Defaults to 32M.

Example configuration:

max_image_pixels: 35M

---

dynamic_thumbnails

Whether to generate new thumbnails on the fly to precisely match the resolution requested by the client. If true then whenever a new resolution is requested by the client the server will generate a new thumbnail. If false the server will pick a thumbnail from a precalculated list. Defaults to false.

Example configuration:

dynamic_thumbnails: true

---

thumbnail_sizes

List of thumbnails to precalculate when an image is uploaded. Associated sub-options are:

• width
• height
• method: i.e. crop, scale, etc.

Example configuration:

thumbnail_sizes:
  - width: 32
    height: 32
    method: crop
  - width: 96
    height: 96
    method: crop
  - width: 320
    height: 240
    method: scale
  - width: 640
    height: 480
    method: scale
  - width: 800
    height: 600
    method: scale

---

media_retention

Controls whether local media and entries in the remote media cache (media that is downloaded from other homeservers) should be removed under certain conditions, typically for the purpose of saving space.

Purging media files will be the carried out by the media worker (that is, the worker that has the enable_media_repo homeserver config option set to 'true'). This may be the main process.

The media_retention.local_media_lifetime and media_retention.remote_media_lifetime config options control whether media will be purged if it has not been accessed in a given amount of time. Note that media is 'accessed' when loaded in a room in a client, or otherwise downloaded by a local or remote user. If the media has never been accessed, the media's creation time is used instead. Both thumbnails and the original media will be removed. If either of these options are unset, then media of that type will not be purged.

Local or cached remote media that has been quarantined will not be deleted. Similarly, local media that has been marked as protected from quarantine will not be deleted.

Example configuration:

media_retention:
    local_media_lifetime: 90d
    remote_media_lifetime: 14d

---

url_preview_enabled

This setting determines whether the preview URL API is enabled. It is disabled by default. Set to true to enable. If enabled you must specify a url_preview_ip_range_blacklist blacklist.

Example configuration:

url_preview_enabled: true

---

url_preview_ip_range_blacklist

List of IP address CIDR ranges that the URL preview spider is denied from accessing. There are no defaults: you must explicitly specify a list for URL previewing to work. You should specify any internal services in your network that you do not want synapse to try to connect to, otherwise anyone in any Matrix room could cause your synapse to issue arbitrary GET requests to your internal services, causing serious security issues.

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

This must be specified if url_preview_enabled is set. It is recommended that you use the following example list as a starting point.

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

Example configuration:

url_preview_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'

---

url_preview_ip_range_whitelist

This option sets a list of IP address CIDR ranges that the URL preview spider is allowed to access even if they are specified in url_preview_ip_range_blacklist. This is useful for specifying exceptions to wide-ranging blacklisted target IP ranges - e.g. for enabling URL previews for a specific private website only visible in your network. Defaults to none.

Example configuration:

url_preview_ip_range_whitelist:
   - '192.168.1.1'

---

url_preview_url_blacklist

Optional list of URL matches that the URL preview spider is denied from accessing. You should use url_preview_ip_range_blacklist in preference to this, otherwise someone could define a public DNS entry that points to a private IP address and circumvent the blacklist. This is more useful if you know there is an entire shape of URL that you know that will never want synapse to try to spider.

Each list entry is a dictionary of url component attributes as returned by urlparse.urlsplit as applied to the absolute form of the URL. See here for more information. Some examples are:

• username
• netloc
• scheme
• path

The values of the dictionary are treated as a filename match pattern applied to that component of URLs, unless they start with a ^ in which case they are treated as a regular expression match. If all the specified component matches for a given list item succeed, the URL is blacklisted.

Example configuration:

url_preview_url_blacklist:
  # blacklist any URL with a username in its URI
  - username: '*'

  # blacklist all *.google.com URLs
  - netloc: 'google.com'
  - netloc: '*.google.com'

  # blacklist all plain HTTP URLs
  - scheme: 'http'

  # blacklist http(s)://www.acme.com/foo
  - netloc: 'www.acme.com'
    path: '/foo'

  # blacklist any URL with a literal IPv4 address
  - netloc: '^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$'

---

max_spider_size

The largest allowed URL preview spidering size in bytes. Defaults to 10M.

Example configuration:

max_spider_size: 8M

---

url_preview_accept_language

A list of values for the Accept-Language HTTP header used when downloading webpages during URL preview generation. This allows Synapse to specify the preferred languages that URL previews should be in when communicating with remote servers.

Each value is a IETF language tag; a 2-3 letter identifier for a language, optionally followed by subtags separated by '-', specifying a country or region variant.

Multiple values can be provided, and a weight can be added to each by using quality value syntax (;q=). '*' translates to any language.

Defaults to "en".

Example configuration:

 url_preview_accept_language:
   - 'en-UK'
   - 'en-US;q=0.9'
   - 'fr;q=0.8'
   - '*;q=0.7'

---

oembed

oEmbed allows for easier embedding content from a website. It can be used for generating URLs previews of services which support it. A default list of oEmbed providers is included with Synapse. Set disable_default_providers to true to disable using these default oEmbed URLs. Use additional_providers to specify additional files with oEmbed configuration (each should be in the form of providers.json). By default this list is empty.

Example configuration:

oembed:
  disable_default_providers: true
  additional_providers:
    - oembed/my_providers.json

---

Captcha

See here for full details on setting up captcha.

---

recaptcha_public_key

This homeserver's ReCAPTCHA public key. Must be specified if enable_registration_captcha is enabled.

Example configuration:

recaptcha_public_key: "YOUR_PUBLIC_KEY"

---

recaptcha_private_key

This homeserver's ReCAPTCHA private key. Must be specified if enable_registration_captcha is enabled.

Example configuration:

recaptcha_private_key: "YOUR_PRIVATE_KEY"

---

enable_registration_captcha

Set to true to require users to complete a CAPTCHA test when registering an account. Requires a valid ReCaptcha public/private key. Defaults to false.

Note that enable_registration must also be set to allow account registration.

Example configuration:

enable_registration_captcha: true

---

recaptcha_siteverify_api

The API endpoint to use for verifying m.login.recaptcha responses. Defaults to https://www.recaptcha.net/recaptcha/api/siteverify.

Example configuration:

recaptcha_siteverify_api: "https://my.recaptcha.site"

---

TURN

Options related to adding a TURN server to Synapse.

---

turn_uris

The public URIs of the TURN server to give to clients.

Example configuration:

turn_uris: [turn:example.org]

---

turn_shared_secret

The shared secret used to compute passwords for the TURN server.

Example configuration:

turn_shared_secret: "YOUR_SHARED_SECRET"

---

turn_username and turn_password

The Username and password if the TURN server needs them and does not use a token.

Example configuration:

turn_username: "TURNSERVER_USERNAME"
turn_password: "TURNSERVER_PASSWORD"

---

turn_user_lifetime

How long generated TURN credentials last. Defaults to 1h.

Example configuration:

turn_user_lifetime: 2h

---

turn_allow_guests

Whether guests should be allowed to use the TURN server. This defaults to true, otherwise VoIP will be unreliable for guests. However, it does introduce a slight security risk as it allows users to connect to arbitrary endpoints without having first signed up for a valid account (e.g. by passing a CAPTCHA).

Example configuration:

turn_allow_guests: false

---

Registration

Registration can be rate-limited using the parameters in the Ratelimiting section of this manual.

---

enable_registration

Enable registration for new users. Defaults to false.

It is highly recommended that if you enable registration, you set one or more or the following options, to avoid abuse of your server by "bots":

• enable_registration_captcha
• registrations_require_3pid
• registration_requires_token

(In order to enable registration without any verification, you must also set enable_registration_without_verification.)

Note that even if this setting is disabled, new accounts can still be created via the admin API if registration_shared_secret is set.

Example configuration:

enable_registration: true

---

enable_registration_without_verification

Enable registration without email or captcha verification. Note: this option is not recommended, as registration without verification is a known vector for spam and abuse. Defaults to false. Has no effect unless enable_registration is also enabled.

Example configuration:

enable_registration_without_verification: true

---

registrations_require_3pid

If this is set, users must provide all of the specified types of 3PID when registering an account.

Note that enable_registration must also be set to allow account registration.

Example configuration:

registrations_require_3pid:
  - email
  - msisdn

---

disable_msisdn_registration

Explicitly disable asking for MSISDNs from the registration flow (overrides registrations_require_3pid if MSISDNs are set as required).

Example configuration:

disable_msisdn_registration: true

---

allowed_local_3pids

Mandate that users are only allowed to associate certain formats of 3PIDs with accounts on this server, as specified by the medium and pattern sub-options.

Example configuration:

allowed_local_3pids:
  - medium: email
    pattern: '^[^@]+@matrix\.org$'
  - medium: email
    pattern: '^[^@]+@vector\.im$'
  - medium: msisdn
    pattern: '\+44'

---

enable_3pid_lookup

Enable 3PIDs lookup requests to identity servers from this server. Defaults to true.

Example configuration:

enable_3pid_lookup: false

---

registration_requires_token

Require users to submit a token during registration. Tokens can be managed using the admin API. Disabling this option will not delete any tokens previously generated. Defaults to false. Set to true to enable.

Note that enable_registration must also be set to allow account registration.

Example configuration:

registration_requires_token: true

---

registration_shared_secret

If set, allows registration of standard or admin accounts by anyone who has the shared secret, even if enable_registration is not set.

This is primarily intended for use with the register_new_matrix_user script (see Registering a user); however, the interface is documented.

See also registration_shared_secret_path.

Example configuration:

registration_shared_secret: <PRIVATE STRING>

---

registration_shared_secret_path

An alternative to registration_shared_secret: allows the shared secret to be specified in an external file.

The file should be a plain text file, containing only the shared secret.

If this file does not exist, Synapse will create a new signing key on startup and store it in this file.

Example configuration:

registration_shared_secret_file: /path/to/secrets/file

Added in Synapse 1.67.0.

---

bcrypt_rounds

Set the number of bcrypt rounds used to generate password hash. Larger numbers increase the work factor needed to generate the hash. The default number is 12 (which equates to 2^12 rounds). N.B. that increasing this will exponentially increase the time required to register or login - e.g. 24 => 2^24 rounds which will take >20 mins. Example configuration:

bcrypt_rounds: 14

---

allow_guest_access

Allows users to register as guests without a password/email/etc, and participate in rooms hosted on this server which have been made accessible to anonymous users. Defaults to false.

Example configuration:

allow_guest_access: true

---

default_identity_server

The identity server which we suggest that clients should use when users log in on this server.

(By default, no suggestion is made, so it is left up to the client. This setting is ignored unless public_baseurl is also explicitly set.)

Example configuration:

default_identity_server: https://matrix.org

---

account_threepid_delegates

Delegate verification of phone numbers to an identity server.

When a user wishes to add a phone number to their account, we need to verify that they actually own that phone number, which requires sending them a text message (SMS). Currently Synapse does not support sending those texts itself and instead delegates the task to an identity server. The base URI for the identity server to be used is specified by the account_threepid_delegates.msisdn option.

If this is left unspecified, Synapse will not allow users to add phone numbers to their account.

(Servers handling the these requests must answer the /requestToken endpoints defined by the Matrix Identity Service API specification.)

Deprecated in Synapse 1.64.0: The email option is deprecated.

Removed in Synapse 1.66.0: The email option has been removed. If present, Synapse will report a configuration error on startup.

Example configuration:

account_threepid_delegates:
    msisdn: http://localhost:8090  # Delegate SMS sending to this local process

---

enable_set_displayname

Whether users are allowed to change their displayname after it has been initially set. Useful when provisioning users based on the contents of a third-party directory.

Does not apply to server administrators. Defaults to true.

Example configuration:

enable_set_displayname: false

---

enable_set_avatar_url

Whether users are allowed to change their avatar after it has been initially set. Useful when provisioning users based on the contents of a third-party directory.

Does not apply to server administrators. Defaults to true.

Example configuration:

enable_set_avatar_url: false

---

enable_3pid_changes

Whether users can change the third-party IDs associated with their accounts (email address and msisdn).

Defaults to true.

Example configuration:

enable_3pid_changes: false

---

auto_join_rooms

Users who register on this homeserver will automatically be joined to the rooms listed under this option.

By default, any room aliases included in this list will be created as a publicly joinable room when the first user registers for the homeserver. If the room already exists, make certain it is a publicly joinable room, i.e. the join rule of the room must be set to 'public'. You can find more options relating to auto-joining rooms below.

As Spaces are just rooms under the hood, Space aliases may also be used.

Example configuration:

auto_join_rooms:
  - "#exampleroom:example.com"
  - "#anotherexampleroom:example.com"

---

autocreate_auto_join_rooms

Where auto_join_rooms are specified, setting this flag ensures that the rooms exist by creating them when the first user on the homeserver registers. This option will not create Spaces.

By default the auto-created rooms are publicly joinable from any federated server. Use the autocreate_auto_join_rooms_federated and autocreate_auto_join_room_preset settings to customise this behaviour.

Setting to false means that if the rooms are not manually created, users cannot be auto-joined since they do not exist.

Defaults to true.

Example configuration:

autocreate_auto_join_rooms: false

---

autocreate_auto_join_rooms_federated

Whether the rooms listed in auto_join_rooms that are auto-created are available via federation. Only has an effect if autocreate_auto_join_rooms is true.

Note that whether a room is federated cannot be modified after creation.

Defaults to true: the room will be joinable from other servers. Set to false to prevent users from other homeservers from joining these rooms.

Example configuration:

autocreate_auto_join_rooms_federated: false

---

autocreate_auto_join_room_preset

The room preset to use when auto-creating one of auto_join_rooms. Only has an effect if autocreate_auto_join_rooms is true.

Possible values for this option are:

• "public_chat": the room is joinable by anyone, including federated servers if autocreate_auto_join_rooms_federated is true (the default).
• "private_chat": an invitation is required to join these rooms.
• "trusted_private_chat": an invitation is required to join this room and the invitee is assigned a power level of 100 upon joining the room.

If a value of "private_chat" or "trusted_private_chat" is used then auto_join_mxid_localpart must also be configured.

Defaults to "public_chat".

Example configuration:

autocreate_auto_join_room_preset: private_chat

---

auto_join_mxid_localpart

The local part of the user id which is used to create auto_join_rooms if autocreate_auto_join_rooms is true. If this is not provided then the initial user account that registers will be used to create the rooms.

The user id is also used to invite new users to any auto-join rooms which are set to invite-only.

It must be configured if autocreate_auto_join_room_preset is set to "private_chat" or "trusted_private_chat".

Note that this must be specified in order for new users to be correctly invited to any auto-join rooms which have been set to invite-only (either at the time of creation or subsequently).

Note that, if the room already exists, this user must be joined and have the appropriate permissions to invite new members.

Example configuration:

auto_join_mxid_localpart: system

---

auto_join_rooms_for_guests

When auto_join_rooms is specified, setting this flag to false prevents guest accounts from being automatically joined to the rooms.

Defaults to true.

Example configuration:

auto_join_rooms_for_guests: false

---

inhibit_user_in_use_error

Whether to inhibit errors raised when registering a new account if the user ID already exists. If turned on, requests to /register/available will always show a user ID as available, and Synapse won't raise an error when starting a registration with a user ID that already exists. However, Synapse will still raise an error if the registration completes and the username conflicts.

Defaults to false.

Example configuration:

inhibit_user_in_use_error: true

---

User session management

---

session_lifetime

Time that a user's session remains valid for, after they log in.

Note that this is not currently compatible with guest logins.

Note also that this is calculated at login time: changes are not applied retrospectively to users who have already logged in.

By default, this is infinite.

Example configuration:

session_lifetime: 24h

---

refresh_access_token_lifetime

Time that an access token remains valid for, if the session is using refresh tokens.

For more information about refresh tokens, please see the manual.

Note that this only applies to clients which advertise support for refresh tokens.

Note also that this is calculated at login time and refresh time: changes are not applied to existing sessions until they are refreshed.

By default, this is 5 minutes.

Example configuration:

refreshable_access_token_lifetime: 10m

---

refresh_token_lifetime: 24h

Time that a refresh token remains valid for (provided that it is not exchanged for another one first). This option can be used to automatically log-out inactive sessions. Please see the manual for more information.

Note also that this is calculated at login time and refresh time: changes are not applied to existing sessions until they are refreshed.

By default, this is infinite.

Example configuration:

refresh_token_lifetime: 24h

---

nonrefreshable_access_token_lifetime

Time that an access token remains valid for, if the session is NOT using refresh tokens.

Please note that not all clients support refresh tokens, so setting this to a short value may be inconvenient for some users who will then be logged out frequently.

Note also that this is calculated at login time: changes are not applied retrospectively to existing sessions for users that have already logged in.

By default, this is infinite.

Example configuration:

nonrefreshable_access_token_lifetime: 24h

---

Metrics

Config options related to metrics.

---

enable_metrics

Set to true to enable collection and rendering of performance metrics. Defaults to false.

Example configuration:

enable_metrics: true

---

sentry

Use this option to enable sentry integration. Provide the DSN assigned to you by sentry with the dsn setting.

NOTE: While attempts are made to ensure that the logs don't contain any sensitive information, this cannot be guaranteed. By enabling this option the sentry server may therefore receive sensitive information, and it in turn may then disseminate sensitive information through insecure notification channels if so configured.

Example configuration:

sentry:
    dsn: "..."

---

metrics_flags

Flags to enable Prometheus metrics which are not suitable to be enabled by default, either for performance reasons or limited use. Currently the only option is known_servers, which publishes synapse_federation_known_servers, a gauge of the number of servers this homeserver knows about, including itself. May cause performance problems on large homeservers.

Example configuration:

metrics_flags:
    known_servers: true

---

report_stats

Whether or not to report homeserver usage statistics. This is originally set when generating the config. Set this option to true or false to change the current behavior. See Reporting Homeserver Usage Statistics for information on what data is reported.

Statistics will be reported 5 minutes after Synapse starts, and then every 3 hours after that.

Example configuration:

report_stats: true

---

report_stats_endpoint

The endpoint to report homeserver usage statistics to. Defaults to https://matrix.org/report-usage-stats/push

Example configuration:

report_stats_endpoint: https://example.com/report-usage-stats/push

---

API Configuration

Config settings related to the client/server API

---

room_prejoin_state

This setting controls the state that is shared with users upon receiving an invite to a room, or in reply to a knock on a room. By default, the following state events are shared with users:

• m.room.join_rules
• m.room.canonical_alias
• m.room.avatar
• m.room.encryption
• m.room.name
• m.room.create
• m.room.topic

To change the default behavior, use the following sub-options:

• disable_default_event_types: boolean. Set to true to disable the above defaults. If this is enabled, only the event types listed in additional_event_types are shared. Defaults to false.

• additional_event_types: A list of additional state events to include in the events to be shared. By default, this list is empty (so only the default event types are shared).

  Each entry in this list should be either a single string or a list of two strings.

  • A standalone string t represents all events with type t (i.e. with no restrictions on state keys).
  • A pair of strings [t, s] represents a single event with type t and state key s. The same type can appear in two entries with different state keys: in this situation, both state keys are included in prejoin state.