By default, this playbook configures the [Synapse](https://github.com/matrix-org/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/matrix-synapse/defaults/main.yml`](../roles/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/matrix-synapse/templates/synapse/homeserver.yaml.j2`](../roles/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](installing.md) 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`](../roles/matrix-synapse/templates/synapse/homeserver.yaml.j2)) by making use of the `matrix_synapse_configuration_extension_yaml` variable. You can find information about this in [`roles/matrix-synapse/defaults/main.yml`](../roles/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/matrix-synapse/defaults/main.yml`](../roles/matrix-synapse/defaults/main.yml).
Certain Synapse administration tasks (managing users and rooms, etc.) can be performed via a web user-interace, if you install [Synapse Admin](configuring-playbook-synapse-admin.md).
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](configuring-playbook-nginx.md#synapse-openid-connect-for-single-sign-on)).
