matrix-docker-ansible-deploy/docs/configuring-playbook-synapse.md

Configuring Synapse (optional)

By default, this playbook configures the Synapse Matrix server, so that it works for the general case. If that's enough for you, you can skip this document.

The playbook provides lots of customization variables you could use to change Synapse's settings.

Their defaults are defined in roles/custom/matrix-synapse/defaults/main.yml and they ultimately end up in the generated /matrix/synapse/config/homeserver.yaml file (on the server). This file is generated from the roles/custom/matrix-synapse/templates/synapse/homeserver.yaml.j2 template.

If there's an existing variable which controls a setting you wish to change, you can simply define that variable in your configuration file (inventory/host_vars/matrix.<your-domain>/vars.yml) and re-run the playbook to apply the changes.

Alternatively, if there is no pre-defined variable for a Synapse setting you wish to change:

• you can either request a variable to be created (or you can submit such a contribution yourself). Keep in mind that it's probably not a good idea to create variables for each one of Synapse's various settings that rarely get used.

• or, you can extend and override the default configuration (homeserver.yaml.j2) by making use of the matrix_synapse_configuration_extension_yaml variable. You can find information about this in roles/custom/matrix-synapse/defaults/main.yml.

• or, if extending the configuration is still not powerful enough for your needs, you can override the configuration completely using matrix_synapse_configuration (or matrix_synapse_configuration_yaml). You can find information about this in roles/custom/matrix-synapse/defaults/main.yml.

Load balancing with workers

To have Synapse gracefully handle thousands of users, worker support should be enabled. It factors out some homeserver tasks and spreads the load of incoming client and server-to-server traffic between multiple processes. More information can be found in the official Synapse workers documentation.

To enable Synapse worker support, update your inventory/host_vars/matrix.DOMAIN/vars.yml file:

matrix_synapse_workers_enabled: true

We support a few configuration presets (matrix_synapse_workers_preset: one-of-each being the default configuration):

• little-federation-helper - a very minimal worker configuration to improve federation performance
• one-of-each - one worker of each supported type

If you'd like more customization power, you can start with one of the presets and tweak various matrix_synapse_workers_*_count variables manually.

If you increase worker counts too much, you may need to increase the maximum number of Postgres connections too (example):

matrix_postgres_process_extra_arguments: [
  "-c 'max_connections=200'"
]

NOTE: Disabling matrix-nginx-proxy (matrix_nginx_proxy_enabled: false) (that is, using your own other webserver when running a Synapse worker setup is likely to cause various troubles (see this issue).

In case any problems occur, make sure to have a look at the list of synapse issues about workers and your journalctl --unit 'matrix-*'.

Synapse Admin

Certain Synapse administration tasks (managing users and rooms, etc.) can be performed via a web user-interace, if you install Synapse Admin.

Synapse + OpenID Connect for Single-Sign-On

If you'd like to use OpenID Connect authentication with Synapse, you'll need some additional reverse-proxy configuration (see our nginx reverse-proxy doc page).

This example configuration is for keycloak, an opensource Identity Provider maintained by Red Hat.

For more detailed documentation on available options and how to setup keycloak, see the Synapse documentation on OpenID Connect with keycloak.

In case you encounter errors regarding the parsing of the variables, you can try to add {% raw %} and {% endraw %} blocks around them. For example ;

matrix_synapse_configuration_extension_yaml: |
  oidc_providers:
    - idp_id: keycloak
      idp_name: "My KeyCloak server"
      issuer: "https://url.ix/auth/realms/{realm_name}"
      client_id: "matrix"
      client_secret: "{{ vault_synapse_keycloak }}"
      scopes: ["openid", "profile"]
      user_mapping_provider:
        config:
          localpart_template: "{% raw %}{{ user.preferred_username }}{% endraw %}"
          display_name_template: "{% raw %}{{ user.name }}{% endraw %}"
          email_template: "{% raw %}{{ user.email }}{% endraw %}"
      allow_existing_users: true # Optional
      backchannel_logout_enabled: true # Optional