DATABASE_URL (required) - where to place the sqlite database seabird-core
will use. This should be in a URL format, so sqlite:tokens.db will be
relative to the current directory and sqlite:///path/to/tokens.db will be
absolute.
SEABIRD_BIND_HOST (optional, defaults to 0.0.0.0:11235) - which host/port
to bind the gRPC service to. Note that it will not be tls encrypted, so you
may want to put it behind a reverse proxy.
RUST_LOG (optional, defaults to info,seabird::server=trace) - this is a
common rust environment variable documented here because we set a default. All
seabird functionality is exposed under seabird.