Add option to redirect logging to stderr. (resolves #154)

Signed-off-by: Jason Volk <jason@zemos.net>

src/core/config/mod.rs

@@ -888,6 +888,15 @@ pub struct Config {
 	#[serde(default)]
 	pub log_thread_ids: bool,
 
+	/// Redirects logging to standard error (stderr). The default is false for
+	/// stdout. For those using our systemd features the redirection to stderr
+	/// occurs as necessary and setting this option should not be required. We
+	/// offer this option for all other users who desire such redirection.
+	///
+	/// default: false
+	#[serde(default)]
+	pub log_to_stderr: bool,
+
 	/// OpenID token expiration/TTL in seconds.
 	///
 	/// These are the OpenID tokens that are primarily used for Matrix account

src/core/log/console.rs

@@ -28,13 +28,13 @@ pub struct ConsoleWriter {
 
 impl ConsoleWriter {
 	#[must_use]
-	pub fn new(_config: &Config) -> Self {
+	pub fn new(config: &Config) -> Self {
 		let journal_stream = get_journal_stream();
 		Self {
 			stdout: io::stdout(),
 			stderr: io::stderr(),
 			_journal_stream: journal_stream.into(),
-			use_stderr: journal_stream.0 != 0,
+			use_stderr: journal_stream.0 != 0 || config.log_to_stderr,
 		}
 	}
 }

tuwunel-example.toml

@@ -733,6 +733,13 @@
 #
 #log_thread_ids = false
 
+# Redirects logging to standard error (stderr). The default is false for
+# stdout. For those using our systemd features the redirection to stderr
+# occurs as necessary and setting this option should not be required. We
+# offer this option for all other users who desire such redirection.
+#
+#log_to_stderr = false
+
 # OpenID token expiration/TTL in seconds.
 #
 # These are the OpenID tokens that are primarily used for Matrix account