Most of the Synapse server's state is in its SQLite database. It also
has a `media_store` directory that needs to be backed up, though.
In order to back up the SQLite database while the server is running, the
database must be in "WAL mode." By default, Synapse leaves the database
in the default "rollback journal mode," which disallows multiple
processes from accessing the database, even for read-only operations.
To change the journal mode:
```sh
sudo systemctl stop synapse
sudo -u synapse sqlite3 /var/lib/synapse/homeserver.db 'PRAGMA journal_mode=WAL;'
sudo systemctl start synapse
```
The *synapse* role and the corresponding `synapse.yml` playbook deploy
Synapse, the reference Matrix homeserver implementation.
Deploying Synapse itself is fairly straightforward: it is packaged by
Fedora and therefore can simply be installed via `dnf` and started by
`systemd`. Making the service available on the Internet, however, is
more involved. The Matrix protocol mostly works over HTTPS on the
standard port (443), so a typical reverse proxy deployment is mostly
sufficient. Some parts of the Matrix protocol, however, involve
communication over an alternate port (8448). This could be handled by a
reverse proxy as well, but since it is a fairly unique port, it could
also be handled by NAT/port forwarding. In order to support both
deployment scenarios (as well as the hypothetical scenario wherein the
Synapse machine is directly accessible from the Internet), the *synapse*
role supports specifying an optional `matrix_tls_cert` variable. If
this variable is set, it should contain the path to a certificate file
on the Ansible control machine that will be used for the "direct"
connections (i.e. on port 8448). If it is not set, the default Apache
certificate will be used for both virtual hosts.
Synapse has a pretty extensive configuration schema, but most of the
options are set to their default values by the *synapse* role. Other
than substituting secret keys, the only exposed configuration option is
the LDAP authentication provider.
Dustin