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Diffstat (limited to 'README.rst')
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1 files changed, 69 insertions, 146 deletions
diff --git a/README.rst b/README.rst index 8e22109973..7cb2c82b79 100644 --- a/README.rst +++ b/README.rst @@ -80,7 +80,10 @@ Thanks for using Matrix! Synapse Installation ==================== -For details on how to install synapse, see `<INSTALL.md>`_. +.. _federation: + +* For details on how to install synapse, see `<INSTALL.md>`_. +* For specific details on how to configure Synapse for federation see `docs/federate.md <docs/federate.md>`_ Connecting to Synapse from a client @@ -93,13 +96,13 @@ 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 `<INSTALL.md#tls-certificates>`_. -An easy way to get started is to login or register via Riot at -https://riot.im/app/#/login or https://riot.im/app/#/register respectively. +An easy way to get started is to login or register via Riot at +https://riot.im/app/#/login or https://riot.im/app/#/register respectively. You will need to change the server you are logging into from ``matrix.org`` -and instead specify a Homeserver URL of ``https://<server_name>:8448`` -(or just ``https://<server_name>`` if you are using a reverse proxy). -(Leave the identity server as the default - see `Identity servers`_.) -If you prefer to use another client, refer to our +and instead specify a Homeserver URL of ``https://<server_name>:8448`` +(or just ``https://<server_name>`` if you are using a reverse proxy). +(Leave the identity server as the default - see `Identity servers`_.) +If you prefer to use another client, refer to our `client breakdown <https://matrix.org/docs/projects/clients-matrix>`_. If all goes well you should at least be able to log in, create a room, and @@ -151,56 +154,6 @@ 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. -Troubleshooting -=============== - -Running out of File Handles ---------------------------- - -If synapse runs out of filehandles, 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 June 2017 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 ``/etc/security/limits.conf`` - -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. - -Help!! Synapse eats all my RAM! -------------------------------- - -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 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_FACTOR`` environment -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. - -Using `libjemalloc <http://jemalloc.net/>`_ can also yield a significant -improvement in overall amount, 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 ``libjemalloc1`` package and adding this line to -``/etc/default/matrix-synapse``:: - - LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libjemalloc.so.1 - -This can make a significant difference on Python 2.7 - it's unclear how -much of an improvement it provides on Python 3.x. Upgrading an existing Synapse ============================= @@ -211,100 +164,19 @@ versions of synapse. .. _UPGRADE.rst: UPGRADE.rst -.. _federation: - -Setting up Federation -===================== - -Federation is the process by which users on different servers can participate -in the same room. For this to work, those other servers must be able to contact -yours to send messages. - -The ``server_name`` in your ``homeserver.yaml`` file determines the way that -other servers will reach yours. By default, they will treat it as a hostname -and try to connect to port 8448. This is easy to set up and will work with the -default configuration, provided you set the ``server_name`` to match your -machine's public DNS hostname, and give Synapse a TLS certificate which is -valid for your ``server_name``. - -For a more flexible configuration, you can set up a DNS SRV record. This allows -you to run your server on a machine that might not have the same name as your -domain name. For example, you might want to run your server at -``synapse.example.com``, but have your Matrix user-ids look like -``@user:example.com``. (A SRV record also allows you to change the port from -the default 8448). - -To use a SRV record, first create your SRV record and publish it in DNS. This -should have the format ``_matrix._tcp.<yourdomain.com> <ttl> IN SRV 10 0 <port> -<synapse.server.name>``. The DNS record should then look something like:: - - $ dig -t srv _matrix._tcp.example.com - _matrix._tcp.example.com. 3600 IN SRV 10 0 8448 synapse.example.com. - -Note that the server hostname cannot be an alias (CNAME record): it has to point -directly to the server hosting the synapse instance. - -You can then configure your homeserver to use ``<yourdomain.com>`` as the domain in -its user-ids, by setting ``server_name``:: - - python -m synapse.app.homeserver \ - --server-name <yourdomain.com> \ - --config-path homeserver.yaml \ - --generate-config - python -m synapse.app.homeserver --config-path homeserver.yaml - -If you've already generated the config file, you need to edit the ``server_name`` -in your ``homeserver.yaml`` file. If you've already started Synapse and a -database has been created, you will have to recreate the database. - -If all goes well, you should be able to `connect to your server with a client`__, -and then join a room via federation. (Try ``#matrix-dev:matrix.org`` as a first -step. "Matrix HQ"'s sheer size and activity level tends to make even the -largest boxes pause for thought.) - -.. __: `Connecting to Synapse from a client`_ - -Troubleshooting ---------------- - -You can use the `federation tester <https://matrix.org/federationtester>`_ to -check if your homeserver is all set. - -The typical failure mode with federation is that when you try to join a room, -it is rejected with "401: Unauthorized". Generally this means that other -servers in the room couldn't access yours. (Joining a room over federation is a -complicated dance which requires connections in both directions). - -So, things to check are: - -* If you are not using a SRV record, check that your ``server_name`` (the part - of your user-id after the ``:``) matches your hostname, and that port 8448 on - that hostname is reachable from outside your network. -* If you *are* using a SRV record, check that it matches your ``server_name`` - (it should be ``_matrix._tcp.<server_name>``), and that the port and hostname - it specifies are reachable from outside your network. - -Another common problem is that people on other servers can't join rooms that -you invite them to. This can be caused by an incorrectly-configured reverse -proxy: see `<docs/reverse_proxy.rst>`_ for instructions on how to correctly -configure a reverse proxy. - -Running a Demo Federation of Synapses -------------------------------------- - -If you want to get up and running quickly with a trio of homeservers in a -private federation, there is a script in the ``demo`` directory. This is mainly -useful just for development purposes. See `<demo/README>`_. - Using PostgreSQL ================ -As of Synapse 0.9, `PostgreSQL <https://www.postgresql.org>`_ is supported as an -alternative to the `SQLite <https://sqlite.org/>`_ database that Synapse has -traditionally used for convenience and simplicity. +Synapse offers two database engines: + * `SQLite <https://sqlite.org/>`_ + * `PostgreSQL <https://www.postgresql.org>`_ + +By default Synapse uses SQLite in and doing so trades performance for convenience. +SQLite is only recommended in Synapse for testing purposes or for servers with +light workloads. -The advantages of Postgres include: +Almost all installations should opt to use PostreSQL. Advantages include: * significant performance improvements due to the superior threading and caching model, smarter query optimiser @@ -440,3 +312,54 @@ sphinxcontrib-napoleon:: Building internal API documentation:: python setup.py build_sphinx + +Troubleshooting +=============== + +Running out of File Handles +--------------------------- + +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 ``/etc/security/limits.conf`` + +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. + +Help!! Synapse eats all my RAM! +------------------------------- + +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_FACTOR`` environment +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. + +Using `libjemalloc <http://jemalloc.net/>`_ can also yield a significant +improvement in overall amount, 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 ``libjemalloc1`` package and adding this line to +``/etc/default/matrix-synapse``:: + + LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libjemalloc.so.1 + +This can make a significant difference on Python 2.7 - it's unclear how +much of an improvement it provides on Python 3.x. |