add support for reading a registration token from a file

Signed-off-by: strawberry <strawberry@puppygock.gay>

src/service/globals/mod.rs

@@ -41,6 +41,7 @@ pub struct Service {
 	pub server_user: OwnedUserId,
 	pub admin_alias: OwnedRoomAliasId,
 	pub turn_secret: String,
+	pub registration_token: Option<String>,
 }
 
 type RateLimitState = (Instant, u32); // Time if last failed try, number of failed tries
@@ -96,6 +97,20 @@ impl crate::Service for Service {
 				})
 			});
 
+		let registration_token =
+			config
+				.registration_token_file
+				.as_ref()
+				.map_or(config.registration_token.clone(), |path| {
+					let Ok(token) = std::fs::read_to_string(path).inspect_err(|e| {
+						error!("Failed to read the registration token file: {e}");
+					}) else {
+						return config.registration_token.clone();
+					};
+
+					Some(token)
+				});
+
 		let mut s = Self {
 			db,
 			config: config.clone(),
@@ -112,6 +127,7 @@ impl crate::Service for Service {
 			server_user: UserId::parse_with_server_name(String::from("conduit"), &config.server_name)
 				.expect("@conduit:server_name is valid"),
 			turn_secret,
+			registration_token,
 		};
 
 		if !s