Synapse: Matrix reference homeserver
Matrix is an ambitious new ecosystem for open federated Instant Messaging and VoIP. The basics you need to know to get up and running are:
Everything in Matrix happens in a room. Rooms are distributed and do not exist on any single server. Rooms can be located using convenience aliases like
Matrix user IDs look like
@matthew:matrix.org(although in the future you will normally refer to yourself and others using a third party identifier (3PID): email address, phone number, etc rather than manipulating Matrix user IDs)
The overall architecture is::
client homeserver <=====================> homeserver client https://somewhere.org/_matrix https://elsewhere.net/_matrix
#matrix:matrix.orgis the official support room for Matrix, and can be accessed by any client from https://matrix.org/docs/projects/try-matrix-now.html or via IRC bridge at irc://irc.freenode.net/matrix.
Synapse is currently in rapid development, but as of version 0.5 we believe it is sufficiently stable to be run as an internet-facing service for real usage!
Matrix specifies a set of pragmatic RESTful HTTP JSON APIs as an open standard, which handle:
These APIs are intended to be implemented on a wide range of servers, services and clients, letting developers build messaging and VoIP functionality on top of the entirely open Matrix ecosystem rather than using closed or proprietary solutions. The hope is for Matrix to act as the building blocks for a new generation of fully open and interoperable messaging and VoIP apps for the internet.
Synapse is a reference "homeserver" implementation of Matrix from the core development team at matrix.org, written in Python/Twisted. It is intended to showcase the concept of Matrix and let folks see the spec in the context of a codebase and let you run your own homeserver and generally help bootstrap the ecosystem.
In Matrix, every user runs one or more Matrix clients, which connect through to a Matrix homeserver. The homeserver stores all their personal chat history and user account information - much as a mail client connects through to an IMAP/SMTP server. Just like email, you can either run your own Matrix homeserver and control and own your own communications and history or use one hosted by someone else (e.g. matrix.org) - there is no single point of control or mandatory service provider in Matrix, unlike WhatsApp, Facebook, Hangouts, etc.
We'd like to invite you to join #matrix:matrix.org (via https://matrix.org/docs/projects/try-matrix-now.html), run a homeserver, take a look at the
Matrix spec, and experiment with the
Thanks for using Matrix!
For support installing or managing Synapse, please join |room|_ (from a matrix.org account if necessary) and ask questions there. We do not use GitHub issues for support requests, only for bug reports and feature requests.
.. |room| replace::
#synapse:matrix.org.. _room: https://matrix.to/#/#synapse:matrix.org
The easiest way to try out your new Synapse installation is by connecting to it from a web client.
Unless you are running a test instance of Synapse on your local machine, in general, you will need to enable TLS support before you can successfully connect from a client: see_.
An easy way to get started is to login or register via Element at https://app.element.io/#/login or https://app.element.io/#/register respectively. You will need to change the server you are logging into from
matrix.organd instead specify a Homeserver URL of
https://if you are using a reverse proxy). If you prefer to use another client, refer to our
If all goes well you should at least be able to log in, create a room, and start sending messages.
By default, registration of new users via Matrix clients is disabled. To enable it, specify
homeserver.yaml. (It is then recommended to also set up CAPTCHA - see _.)
enable_registrationis set to
true, it is possible to register a user via a Matrix client.
Your new user name will be formed partly from the
server_name, and partly from a localpart you specify when you create the account. Your name will take the form of::
(pronounced "at localpart on my dot domain dot name").
As when logging in, you will need to specify a "Custom server". Specify your desired
localpartin the 'User name' box.
For details on having Synapse manage your federation TLS certificates automatically, please see_.
Matrix serves raw user generated data in some APIs - specifically the
content repository endpoints_.
Whilst we have tried to mitigate against possible XSS attacks (e.g. https://github.com/matrix-org/synapse/pull/1021) we recommend running matrix homeservers on a dedicated domain name, to limit any malicious user generated content served to web browsers a matrix API from being able to attack webapps hosted on the same domain. This is particularly true of sharing a matrix webclient and server on the same domain.
See https://github.com/vector-im/riot-web/issues/1977 and https://developer.github.com/changes/2014-04-25-user-content-security for more details.
The instructions for upgrading synapse are in
UPGRADE.rst_. Please check these instructions as upgrading may require extra steps for some versions of synapse.
.. _UPGRADE.rst: UPGRADE.rst
It is recommended to put a reverse proxy such as
nginx, `Apache <https://httpd.apache.org/docs/current/mod/modproxyhttp.html>`,
relayd_ in front of Synapse. One advantage of doing so is that it means that you can expose the default https port (443) to Matrix clients without needing to run Synapse with root privileges.
For information on configuring one, see_.
Identity servers have the job of mapping email addresses and other 3rd Party IDs (3PIDs) to Matrix user IDs, as well as verifying the ownership of 3PIDs before creating that mapping.
They are not where accounts or credentials are stored - these live on home servers. Identity Servers are just for mapping 3rd party IDs to matrix IDs.
This process is very security-sensitive, as there is obvious risk of spam if it is too easy to sign up for Matrix accounts or harvest 3PID data. In the longer term, we hope to create a decentralised system to manage it (
matrix-doc #712), but in the meantime, the role of managing trusted identity in the Matrix ecosystem is farmed out to a cluster of known trusted ecosystem partners, who run 'Matrix Identity Servers' such as
Sydent, whose role is purely to authenticate and track 3PID logins and publish end-user public keys.
You can host your own copy of Sydent, but this will prevent you reaching other users in the Matrix ecosystem via their email address, and prevent them finding you. We therefore recommend that you use one of the centralised identity servers at
To reiterate: the Identity server will only be used if you choose to associate an email address with your account, or send an invite to another user via their email address.
Users can reset their password through their client. Alternatively, a server admin can reset a users password using the
admin API_ or by directly editing the database as shown below.
First calculate the hash of the new password::
$ ~/synapse/env/bin/hash_password Password: Confirm password: $2a$12$xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Then update the
userstable in the database::
UPDATE users SET password_hash='$2a$12$xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx' WHERE name='@test:test.com';
Join our developer community on Matrix:
Before setting up a development environment for synapse, make sure you have the system dependencies (such as the python header files) installed - see
Installing from source_.
To check out a synapse for development, clone the git repo into a working directory of your choice::
git clone https://github.com/matrix-org/synapse.git cd synapse
Synapse has a number of external dependencies, that are easiest to install using pip and a virtualenv::
python3 -m venv ./env source ./env/bin/activate pip install -e ".[all,test]"
This will run a process of downloading and installing all the needed dependencies into a virtual env. If any dependencies fail to install, try installing the failing modules individually::
pip install -e "module-name"
Once this is done, you may wish to run Synapse's unit tests to check that everything is installed correctly::
python -m twisted.trial tests
This should end with a 'PASSED' result (note that exact numbers will differ)::
Ran 1337 tests in 716.064s
PASSED (skips=15, successes=1322)
We recommend using the demo which starts 3 federated instances running on ports
(to stop, you can use
If you just want to start a single instance of the app and run it directly::
# Create the homeserver.yaml config once python -m synapse.app.homeserver \ --server-name my.domain.name \ --config-path homeserver.yaml \ --generate-config \ --report-stats=[yes|no]
Start the app
python -m synapse.app.homeserver --config-path homeserver.yaml
Synapse is accompanied by
SyTest_, a Matrix homeserver integration testing suite, which uses HTTP requests to access the API as a Matrix client would. It is able to run Synapse directly from the source tree, so installation of the server is not required.
Testing with SyTest is recommended for verifying that changes related to the Client-Server API are functioning correctly. See the
installation instructions_ for details.
Synapse uses a number of platform dependencies such as Python and PostgreSQL, and aims to follow supported upstream versions. See the_ document for more details.
Need help? Join our community support room on Matrix:
If synapse runs out of file handles, it typically fails badly - live-locking at 100% CPU, and/or failing to accept new TCP connections (blocking the connecting client). Matrix currently can legitimately use a lot of file handles, thanks to busy rooms like #matrix:matrix.org containing hundreds of participating servers. The first time a server talks in a room it will try to connect simultaneously to all participating servers, which could exhaust the available file descriptors between DNS queries & HTTPS sockets, especially if DNS is slow to respond. (We need to improve the routing algorithm used to be better than full mesh, but as of March 2019 this hasn't happened yet).
If you hit this failure mode, we recommend increasing the maximum number of open file handles to be at least 4096 (assuming a default of 1024 or 256). This is typically done by editing
Separately, Synapse may leak file handles if inbound HTTP requests get stuck during processing - e.g. blocked behind a lock or talking to a remote server etc. This is best diagnosed by matching up the 'Received request' and 'Processed request' log lines and looking for any 'Processed request' lines which take more than a few seconds to execute. Please let us know at #synapse:matrix.org if you see this failure mode so we can help debug it, however.
First, ensure you are running the latest version of Synapse, using Python 3 with a PostgreSQL database.
Synapse's architecture is quite RAM hungry currently - we deliberately cache a lot of recent room data and metadata in RAM in order to speed up common requests. We'll improve this in the future, but for now the easiest way to either reduce the RAM usage (at the risk of slowing things down) is to set the almost-undocumented
SYNAPSE_CACHE_FACTORenvironment variable. The default is 0.5, which can be decreased to reduce RAM usage in memory constrained enviroments, or increased if performance starts to degrade.
However, degraded performance due to a low cache factor, common on machines with slow disks, often leads to explosions in memory use due backlogged requests. In this case, reducing the cache factor will make things worse. Instead, try increasing it drastically. 2.0 is a good starting value.
libjemalloc_ can also yield a significant improvement in overall memory use, and especially in terms of giving back RAM to the OS. To use it, the library must simply be put in the LD_PRELOAD environment variable when launching Synapse. On Debian, this can be done by installing the
libjemalloc1package and adding this line to
This can make a significant difference on Python 2.7 - it's unclear how much of an improvement it provides on Python 3.x.
If you're encountering high CPU use by the Synapse process itself, you may be affected by a bug with presence tracking that leads to a massive excess of outgoing federation requests (see
discussion_). If metrics indicate that your server is also issuing far more outgoing federation requests than can be accounted for by your users' activity, this is a likely cause. The misbehavior can be worked around by setting the following in the Synapse config file:
.. code-block:: yaml
presence: enabled: false
The typical failure mode here is that you send an invitation to someone to join a room or direct chat, but when they go to accept it, they get an error (typically along the lines of "Invalid signature"). They might see something like the following in their logs::
2019-09-11 19:32:04,271 - synapse.federation.transport.server - 288 - WARNING - GET-11752 - authenticate_request failed: 401: Invalid signature for server with key ed25519:a_EqML: Unable to verify signature for
This is normally caused by a misconfiguration in your reverse-proxy. See_ and double-check that your settings are correct.
.. |support| image:: https://img.shields.io/matrix/synapse:matrix.org?label=support&logo=matrix :alt: (get support on #synapse:matrix.org) :target: https://matrix.to/#/#synapse:matrix.org
.. |development| image:: https://img.shields.io/matrix/synapse-dev:matrix.org?label=development&logo=matrix :alt: (discuss development on #synapse-dev:matrix.org) :target: https://matrix.to/#/#synapse-dev:matrix.org
.. |license| image:: https://img.shields.io/github/license/matrix-org/synapse :alt: (check license in LICENSE file) :target: LICENSE
.. |pypi| image:: https://img.shields.io/pypi/v/matrix-synapse :alt: (latest version released on PyPi) :target: https://pypi.org/project/matrix-synapse
.. |python| image:: https://img.shields.io/pypi/pyversions/matrix-synapse :alt: (supported python versions) :target: https://pypi.org/project/matrix-synapse