The `-t` option sets the image tag. Official images are tagged `matrixdotorg/synapse:<version>` where `<version>` is the same as the release tag in the synapse git repository.
* ``SYNAPSE_SERVER_NAME`` (mandatory), the current server public hostname.
* ``SYNAPSE_CONFIG_PATH``, path to a custom config file (will ignore all
other options then).
* ``SYNAPSE_NO_TLS``, set this variable to disable TLS in Synapse (use this if
you run your own TLS-capable reverse proxy).
* ``SYNAPSE_WEB_CLIENT``, set this variable to enable the embedded Web client.
* ``SYNAPSE_ENABLE_REGISTRATION``, set this variable to enable registration on
the Synapse instance.
* ``SYNAPSE_ALLOW_GUEST``, set this variable to allow guest joining this server.
* ``SYNAPSE_EVENT_CACHE_SIZE``, the event cache size [default `10K`].
* ``SYNAPSE_REPORT_STATS``, set this variable to `yes` to enable anonymous
statistics reporting back to the Matrix project which helps us to get funding.
Shared secrets, these will be initialized to random values if not set:
* ``SYNAPSE_REGISTRATION_SHARED_SECRET``, secret for registrering users if
registration is disable.
* ``SYNAPSE_MACAROON_SECRET_KEY``, secret for Macaroon.
Database specific values (will use SQLite if not set):
*`POSTGRES_DATABASE` - The database name for the synapse postgres database. [default: `matrix`]
*`POSTGRES_HOST` - The host of the postgres database if you wish to use postgresql instead of sqlite3. [default: `db` which is useful when using a container on the same docker network in a compose file where the postgres service is called `db`]
*`POSTGRES_PASSWORD` - The password for the synapse postgres database. **If this is set then postgres will be used instead of sqlite3.** [default: none] **NOTE**: You are highly encouraged to use postgresql! Please use the compose file to make it easier to deploy.
*`POSTGRES_USER` - The user for the synapse postgres database. [default: `matrix`]