Fediversity/matrix/synapse/README.md

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# Installation and configuration of Synapse

Mind you: this an installation on Debian Linux (at least for now).

Start by installing the latest Synapse server, see the [upstream
documentation](https://element-hq.github.io/synapse/latest/setup/installation.html).

```
apt install -y lsb-release wget apt-transport-https build-essential python3-dev libffi-dev \
               python3-pip python3-setuptools sqlite3 \
               libssl-dev virtualenv libjpeg-dev libxslt1-dev libicu-dev git python3-jinja2

wget -O /usr/share/keyrings/matrix-org-archive-keyring.gpg https://packages.matrix.org/debian/matrix-org-archive-keyring.gpg

echo "deb [signed-by=/usr/share/keyrings/matrix-org-archive-keyring.gpg] https://packages.matrix.org/debian/ $(lsb_release -cs) main" |
    tee /etc/apt/sources.list.d/matrix-org.list

apt update
apt install matrix-synapse-py3
```

This leaves a very basic configuration in `/etc/matrix-synapse/homeserver.yaml`
and  two settings under `/etc/conf.d`. All other configuration items will also
be configured with yaml-files in this directory.

Configure the domain you with to use in `/etc/matrix-synapse/conf.d/server_name.yaml`.
What you configure here will also be the global part of your Matrix handles
(the part after the colon). Also add the URL clients should connect to:

```
server_name: example.com
public_baseurl: https://matrix.example.com/
```

The `public_baseurl` will probably be different than the `server_name`, see
also [Delegation and DNS](#Delegation).

You now have a standard Matrix server that uses sqlite. You really don't want
to use this in production, so probably want to replace this with PostgreSQL.

There are two different ways to configure Synapse, documented here:

* [Monolithic](monolithic)
* [Workers](workers)

We'll use Synapse, using the workers architecture to make it scalable, flexible and reusable.


# Listeners

A fresh installation configures one listener, for both client and federation
traffic. This listens on port 8008 on localhost (IPv4 and IPv6) and does not
do TLS:

```
listeners:
  - port: 8008
    tls: false
    type: http
    x_forwarded: true
    bind_addresses: ['::1', '127.0.0.1']
    resources:
      - names: [client, federation]
        compress: false
```

# Database

The default installation leaves you with an sqlite3 database. Nice for experimenting, but
unsuitable for a production environment.

[Here's how you setup PostgreSQL](../postgresql).

Once you've created a database and user in PostgreSQL, you configure Synapse
to use it.

First delete (or comment out) the SQLITE datbase in `homeserver.yaml`:

```
#database:
#  name: sqlite3
#  args:
#    database: /var/lib/matrix-synapse/homeserver.db
```

Then create the database configuration for PostgreSQL in
`conf.d/database.yaml`:

```
database:
  name: psycopg2
  args:
    user: synapse
    password: <password>
    dbname: synapse
    host: /var/run/postgresql
    cp_min: 5
    cp_max: 10
```

Note: you configure the directory where the UNIX socket file lives, not the
actual file.

Of course, if you use localhost, you should configure it like this:

```
    host: localhost
    port: 5432
```

After changing the database, restart Synapse and check whether it can connect
and create the tables it needs.


# Create admin

Synapse doesn't create an admin account at install time, so you'll have to do
that yourself.

You need to set a `registration_shared_secret` for this, set that in
`conf.d/keys.yaml` like this:

```
registration_shared_secret: xxxx
```

You can create such a key by running `pwgen -csn 52 1`. Restart Synapse after
setting this key.

Now create an admin user. Login and issue this command:

```
register_new_matrix_user -u admin -a -c /etc/matrix-synapse/conf.d/keys.yaml
```

This will ask for a password, choose a safe one.


# Logging

Logging is configured in `log.yaml`. Some logging should go to systemd, the
more specific logging to Synapse's own logfile(s).

This part is yet to be completed, the default configuration is adequate for
most cases.

# Delegation and DNS {#Delegation}

If you run your server under a different FQDN than just the domain name you
want to use, you need to delegate: point from your domain to the server.

Example. You want to use example.com for your domain, but your server is
called matrix.example.com. To make that work, you need to serve 2 bits of
JSON-code on example.com to point clients and servers to the correct
machine: matrix.example.com.

Pointing servers to the correct server is done by publishing this bit of
JSON-code under `https://example.com/.well-known/matrix/server`:

```
{
  "m.homeserver": {"base_url": "https://matrix.example.com"}
}
```

Pointing clients to the correct server needs this at
`https://example.com/.well-known/matrix/client`:

```
{
  "m.server": "matrix.example.com"
}
```

Very important: both names (example.com and matrix.example.com) must be A
and/or AAAA records in DNS, not CNAME.

See [nginx](../nginx) for details about how to publish this data.


# E-mail {#Email}

Synapse should probably be able to send out e-mails; notifications for those
who want that, and password reset for those who need one.

You configure this under the section `email` (yes, really). 

First of all, you need an SMTP-server that is configured to send e-mail for
your domain. Configuring that is out of scope, we'll assume we can use the
server `smtp.example.com`.

Configure this in `conf.d/email.yaml`:

```
email:
  smtp_host: smtp.example.com
  smtp_port: 465
  smtp_user: matrix@example.com
  smtp_pass: SuperSecretPassword
  force_tls: true
  notif_from: "Your Matrix server <matrix@example.com>"
```

This configures an SMTP-connection with SSL (port 465, `force_tls`). See Matrix'
[email documentation](https://element-hq.github.io/synapse/latest/usage/configuration/config_documentation.html?highlight=require_transport_security#email)
for more information.


# Media store {#mediastore}

Files and avatars need to be stored somewhere, we configure these options in
`conf.d/mediastore.yaml`:

```
media_store_path: /var/lib/matrix-synapse/media
enable_authenticated_media: true
max_upload_size: 50M
url_preview_enabled: true
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'
```

These are a few sane (?) defaults, check [Matrix' documentation](https://element-hq.github.io/synapse/latest/usage/configuration/config_documentation.html?highlight=media_store_path#media-store)
for many more options.


# Homeserver blocking {#blocking}

This is a series of options that can be used to block and/or limit users. The
whole list of options can be found in [Matrix' documentation](https://element-hq.github.io/synapse/latest/usage/configuration/config_documentation.html?highlight=mau_stats_only%3A#homeserver-blocking),
we're going to pick out a few useful ones.

Let's configure these options in `conf.d/homeserver_blocking.yaml`.

```
admin_contact: matrixadmin@example.com
mau_stats_only: true
max_avatar_size: 2M
allowed_avatar_mimetypes:
  - "image/png"
  - "image/jpeg"
  - "image/gif"
forgotten_room_retention_period: 7d
```


# Authentication {#authentication}

Logging in can be done in basically two ways: an internal or external
database. Let's start with the first: users and their passwords are stored in
Synapse's database.

We use `conf.d/authentication.yaml` to configure this stuff.

```
password_config:
  policy:
    enabled: true
    localdb_enabled: true
    pepper: <random string>
    minimum_length: 8
    require_digit: true
    require_symbol: true
    require_lowercase: true
    require_uppercase: true
```

With this bit, we configure Synapse to let users pick and change their own
passwords, as long as they meet the configured conditions. Mind you: `pepper` is
a secret random string that should *NEVER* be changed after initial setup. 

But in a bigger environment you'll probably want to use some authentication
backend, such as LDAP. LDAP is configured by means of a module (see
[Synapse LDAP auth Provider](https://github.com/matrix-org/matrix-synapse-ldap3/)
on Github).

Configuring Synapse to use LDAP, would be something like this:

```
password_config:
  policy:
    enabled: only_for_reauth
    localdb_enabled: false

password_providers:
  - module: "ldap_auth_provider.LdapAuthProvider"
    config:
      enabled: true
      uri: "ldap://ldap.example.com:389"
      start_tls: true
      base: "ou=users,dc=example,dc=com"
      attributes:
         uid: "uid"
         mail: "mail"
         name: "cn"
      filter: "(&(objectClass=posixAccount)(accountStatus=active))"

      mode: "search"
      bind_dn: "cn=matrix,ou=service,dc=example,dc=com"
      bind_password: "<very secure password>"
```

This would connect to ldap.example.com over TLS, and authenticate users that
live under `ou=users,dc=example,dc=com` and that are active Posix
accounts. Users will not be able to change their passwords via Matrix, they
have to do that in LDAP.

The bottom 3 lines enable search mode, necessary to find users' displayname
and e-mail address. These values are in LDAP under the attributes "mail" and
"cn" (completely dependent on your LDAP DIT of course, this setup is common
for OpenLDAP). The bind_dn and bind_password are for the account Synapse can
use to connect and search, necessary if anonymous access is prohibited.


# Server configuration {#serverconfig}

See [Define your homeserver name and other base options](https://element-hq.github.io/synapse/latest/usage/configuration/config_documentation.html?highlight=require_auth_for_profile_requests#server)
in the Synapse documentation.

It would be logical to put the next options under `conf.d/server.yaml`, but
Debian insists on `conf.d/server_name.yaml` existing and containing the name
of the domain. So we'll use that file for the next options as well. Add these
options:

```
presence:
  enabled: true
  include_offline_users_on_sync: false

require_auth_for_profile_requests: true
allow_public_rooms_over_federation: true

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'

filter_timeline_limit: 500
delete_stale_devices_after: 1y
```

These should be reasonable defaults, but do check the [Server block](https://element-hq.github.io/synapse/latest/usage/configuration/config_documentation.html#server)
in Synapse's documentation for more options and information.


# Registration {#Registration}

Registration of new users is configured under `conf.d/registration.yaml`:

```
enable_registration: false
enable_registration_without_verification: false
registrations_require_3pid: email
registration_shared_secret: <long random string>
allow_guest_access: false

enable_set_displayname: false
enable_3pid_changes: false
```

The last two lines prohibit users to change their displayname and 3pid-data
(i.e. e-mail address and phone number). In many cases you'd want them to be
able to set these, of course. But when you use LDAP, which provides these
values, you don't want users to change those.

See for more options [Synapse's documentation](https://element-hq.github.io/synapse/latest/usage/configuration/config_documentation.html#registration).


# TURN

Check for more information about [how to configure the TURN
server](../coturn) or [LiveKit](../element-call#livekit). You probably want
LiveKit, but read on if you choose coturn.

It might be useful to use both coturn and LiveKit, so as to support both
legacy and EC calls, but you'd need to tweak the configurations so that they
don't bite each other.

Once you've set up your TURN server, configure it in
Synapse, in `conf.d/turn.yaml`:

```
turn_shared_secret: "<long random string>"
turn_uris:
  - "turn:turn.matrixdev.example.com?transport=udp"
  - "turn:turn.matrixdev.example.com?transport=tcp"
turn_user_lifetime: 86400000
turn_allow_guests: true
```

Restart Synapse to activate this bit.


# Consent Tracking {#consenttracking}

As administrator you sometimes need to push a message to all your users. See
the [Synapse documentation](https://element-hq.github.io/synapse/latest/server_notices.html)
to see how to configure that.

It's also necessary for moderation ([see Draupnir](../draupnir)).


## Server Notices

Server notices allow administrators to send messages to users, much like the
`wall` functionality in UNIX/Linux.

Add this bit of info to `conf.d/server_notices.yaml`:

```
server_notices:
  system_mxid_localpart: server
  system_mxid_display_name: "Server Notices"
# system_mxid_avatar_url: "mxc://example.com/QBBZcaxfrrpvreGeNhqRaCjG"
  room_name: "Server Notices"
# room_avatar_url: "mxc://example.com/QBBZcaxfrrpvreGeNhqRaCjG"
  room_topic: "Room used by your server admin to notice you of important
information"
  auto_join: true
```

This means that the user sending the messages (who isn't really a user anyway)
is `server@example.com`, with the display name `Server Notices`. The room that users receive
these messages in is called the same. The room will be created if it doesn't
yet exist, every user that receives a server message will be put in a room
with that name.

Every user gets his own room, so if you send a server notice to 100 users,
there will be (at least) 100 rooms by that name, all containing 1 user.

The option `auto_join` means that users will automatically join the room as
soon as it's created. They can leave afterwards, but they'll be put into it again
as soon as they receive another server message.

The two commented out options are the avatars for user and room. This is a bit
tricky. You'll need to upload an image to a room first, so that it's present
in the media store. Then you can refer to it by the ID it gets, in the way
shown above. These avatars will only be set or changed when you send a server
notice.

Important bit: you must upload these pictures to an unencrypted room. Pictures
in an encrypted room are... well... encrypted, and that causes a problem for
the thumbnailer. Pictures in encrypted rooms are stored as MIME type
`application/octet-stream`, you want one of the formats you configured under
[Homeserver Blocking](#blocking). Or, if you haven't defined a whitelist, at
least an image mimetype...

Apparently this was a bug that's supposed to be fixed in Synapse 1.20, but we
haven't tested that yet.

You can find the ID of the picture in the database (table `local_media_repository`)
or, more conveniently, in [Synapse-Admin](../synapse-admin), which is also
where you'll want to go if you want to send a server notice.

In Synapse-Admin, open the User tab, select the user(s) you want to send a
notice to, and click "Send Server Notices".

If the result is that you're returned to the login screen of Synapse-Admin,
there was an error sending the notice. Check the Synapse logs.


## Consent template

You can force your users to accept an agreement before you let them on your
machine, see the [Synapse Documentation](https://element-hq.github.io/synapse/latest/consent_tracking.html#support-in-synapse-for-tracking-agreement-to-server-terms-and-conditions).

First, make the directory where you want Synapse to search for the document,
we create the directory `consent_policy`:


```
mkdir -p /var/lib/matrix-synapse/consent_policy/en
```

You'll have to add the directory `en` under that, as every document is assumed
to be in English. Support for other languages is on the wish list.

Create a Jinja2 template with the texts you want: the text users have to agree
to before they can use the service, and the text users that have already
agreed will see. Something like this:

```
<!doctype html>
<html lang="en">
  <head>
    <title>Example End User Policy</title>
  </head>
  <body>
  {% if has_consented %}
    <p>
      You have already accepted the Example End User Policy.
    </p>
  {% else %}
<h1>Example End User Policy</h1>

These are the terms under which you can use this service. Unless you accept these terms, you
will not be allowed to send any messages.

<ol>
  <li>You will not be abusive to other users, be they on this server or on an other.
  <li>You will not do other nasty stuff.
  <li>Basically: you will behave like a good person.
</ol>

We promise you a few things too:

<ol>
  <li>We'll keep your data safe
  <li>We won't snoop on you
  <li>We'll only turn you in with the authorities if you do nasty stuff.
</ol>

If you accept these terms, you can use this system.
    {% if not public_version %}
      <!-- The variables used here are only provided when the 'u' param is given to the homeserver -->
      <form method="post" action="consent">
        <input type="hidden" name="v" value="{{version}}"/>
        <input type="hidden" name="u" value="{{user}}"/>
        <input type="hidden" name="h" value="{{userhmac}}"/>
        <input type="submit" value="I accept"/>
      </form>
    {% endif %}
  {% endif %}
  </body>
</html>
```

The name of this document needs to be a version name with the extension `.html`.
Say you want your users to accept version 0.1, the file must be named
0.1.html. This version is referred to in the configuration.

After a user has agreed to this policy, he is presented with `success.html`,
which you will also have to make (although it's not mentioned in the
documentation). This doesn't have to be very complicated.

```
<!doctype html>
<html lang="en">
  <head>
    <title>ProcoliX End User Policy</title>
  </head>
  <body>
<p>You have agreed to our End User Policy, you can now use our service.</p>

<p>Have fun!</p>
  </body>
</html>
```

We now have the texts ready, time to configure Synapse to use it.

Create a `form_secret`:

```
pwgen -csny 30 1
```

Add this bit to `conf.d/server_notices.yaml`:

```
form_secret: "<previously generated secret>"
user_consent:
  require_at_registration: true
  policy_name: "Example End User Policy"
  template_dir: consent_policy
  version: <version>
  server_notice_content:
    msgtype: m.text
    body: >-
      You have to agree to our End User Policy before you can use this
      service. Please read and accept it at %(consent_uri)s.
  block_events_error: >-
    You haven't accepted the End User Policy yet, so you can't post any
    messages yet. Please read and accept the policy at %(consent_uri)s.
```

Last bit it to enable the consent tracking on all listeners where `client` is
active. We have only one listener, so we add `consent` to that:

```
listeners:
  - port: 8008
    tls: false
    type: http
    x_forwarded: true
    bind_addresses: ['::1', '127.0.0.1']
    resources:
      - names:
        - client
        - consent
        - federation
        compress: false
```

Restart Synapse for these changes to take effect.

If you update your policy, you'll have to copy the current one to a new
version, edit that (e.g. `0.2.html`) and change the `version` to the new
document. Restart Synapse after that. Your users will all have to agree to the
new policy.

The options `server_notice_content` and `block_events_error` do not seem to be
used, this is something that needs to be investigated.