move syslog stuff to a submoudle of signal-gateway-bin and make it optional

signal-gateway-bin/src/main.rs

@@ -2,61 +2,15 @@ use conf::Conf;
 use hyper::service::service_fn;
 use hyper_util::rt::TokioIo;
 use hyper_util::server::conn::auto;
-use signal_gateway::{Gateway, GatewayConfig, Level, LogMessage};
+use signal_gateway::{Gateway, GatewayConfig};
-use std::{net::SocketAddr, str::FromStr, sync::Arc, time::Duration};
+use std::{net::SocketAddr, sync::Arc, time::Duration};
-use syslog_rfc5424::{SyslogMessage, SyslogSeverity};
+use tokio::net::TcpListener;
-use tokio::net::{TcpListener, UdpSocket};
 use tokio_util::sync::CancellationToken;
 use tracing::{error, info, warn};
 use tracing_subscriber::EnvFilter;
 
-/// Convert SyslogSeverity to our Level enum
+mod syslog;
-fn severity_to_level(sev: SyslogSeverity) -> Level {
+use syslog::SyslogUdpConfig;
-    match sev {
-        SyslogSeverity::SEV_EMERG => Level::EMERGENCY,
-        SyslogSeverity::SEV_ALERT => Level::ALERT,
-        SyslogSeverity::SEV_CRIT => Level::CRITICAL,
-        SyslogSeverity::SEV_ERR => Level::ERROR,
-        SyslogSeverity::SEV_WARNING => Level::WARNING,
-        SyslogSeverity::SEV_NOTICE => Level::NOTICE,
-        SyslogSeverity::SEV_INFO => Level::INFO,
-        SyslogSeverity::SEV_DEBUG => Level::DEBUG,
-    }
-}
-
-/// Convert a SyslogMessage to a LogMessage, extracting structured data for tracing metadata
-fn syslog_to_log_message(msg: SyslogMessage, sd_id: &str) -> LogMessage {
-    let level = severity_to_level(msg.severity);
-    let mut builder = LogMessage::builder(level, msg.msg);
-
-    if let Some(ts) = msg.timestamp {
-        builder = builder.timestamp(ts);
-    }
-    if let Some(nanos) = msg.timestamp_nanos {
-        builder = builder.timestamp_nanos(nanos);
-    }
-    if let Some(hostname) = msg.hostname {
-        builder = builder.hostname(hostname);
-    }
-    if let Some(appname) = msg.appname {
-        builder = builder.appname(appname);
-    }
-
-    // Extract tracing metadata from structured data
-    if let Some(sd_element) = msg.sd.find_sdid(sd_id) {
-        if let Some(module) = sd_element.get("module") {
-            builder = builder.module_path(module.clone());
-        }
-        if let Some(file) = sd_element.get("file") {
-            builder = builder.file(file.clone());
-        }
-        if let Some(line) = sd_element.get("line") {
-            builder = builder.line(line.clone());
-        }
-    }
-
-    builder.build()
-}
 
 #[derive(Conf, Debug)]
 struct Config {
@@ -66,12 +20,8 @@ struct Config {
     /// Socket to listen for HTTP requests (GET /health, POST /alert)
     #[conf(long, env, default_value = "0.0.0.0:8000")]
     http_listen_addr: SocketAddr,
-    /// Socket to listen for UDP messages, in syslog RFC 5424 format
+    #[conf(flatten, prefix)]
-    #[conf(long, env, default_value = "0.0.0.0:5424")]
+    syslog_udp: Option<SyslogUdpConfig>,
-    udp_listen_addr: SocketAddr,
-    /// Structured data ID for tracing metadata (module, file, line) in syslog messages
-    #[conf(long, env, default_value = "tracing-meta@64700")]
-    sd_id: String,
     #[conf(flatten)]
     gateway: GatewayConfig,
 }
@@ -123,9 +73,6 @@ async fn main() {
     let listener = TcpListener::bind(config.http_listen_addr).await.unwrap();
     info!("Listening for http on {}", config.http_listen_addr);
 
-    let udp_socket = UdpSocket::bind(config.udp_listen_addr).await.unwrap();
-    info!("Listening for udp on {}", config.udp_listen_addr);
-
     // Listen for ctrl-c
     let thread_token = token.clone();
     tokio::task::spawn(async move {
@@ -136,7 +83,11 @@ async fn main() {
 
     // Start the two server tasks
     let _http_task = start_http_task(listener, gateway.clone());
-    let _udp_task = start_udp_task(udp_socket, gateway.clone(), config.sd_id);
+    let _udp_task = if let Some(syslog_udp) = &config.syslog_udp {
+        Some(syslog_udp.start_udp_task(gateway.clone()).await.unwrap())
+    } else {
+        None
+    };
 
     // Run gateway task and block on it returning. Note that it exits if the token is canceled.
     gateway.run().await;
@@ -178,59 +129,3 @@ fn start_http_task(listener: TcpListener, gateway: Arc<Gateway>) -> tokio::task:
         }
     })
 }
-
-fn start_udp_task(
-    udp_socket: UdpSocket,
-    gateway: Arc<Gateway>,
-    sd_id: String,
-) -> tokio::task::JoinHandle<()> {
-    // Loop waiting for UDP syslog messages
-    tokio::task::spawn(async move {
-        let mut buf = vec![0u8; 8192];
-        loop {
-            let Ok((len, _addr)) = udp_socket
-                .recv_from(&mut buf)
-                .await
-                .inspect_err(|err| error!("Error receiving UDP packet: {err}"))
-            else {
-                continue;
-            };
-
-            let Ok(text) = str::from_utf8(&buf[0..len])
-                .inspect_err(|err| error!("UDP packet was not utf8: {err}"))
-            else {
-                continue;
-            };
-
-            let Ok(syslog_msg) = SyslogMessage::from_str(text)
-                .inspect_err(|err| error!("UDP packet was not valid syslog: {err}:\n{text}"))
-            else {
-                continue;
-            };
-
-            let log_msg = syslog_to_log_message(syslog_msg, &sd_id);
-            gateway.handle_log_message(log_msg).await;
-        }
-    })
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn test_syslog_parsing() {
-        SyslogMessage::from_str(
-            "<12>1 2025-11-08T02:24:10.815221698+00:00 ip-172-31-5-8 app 92748 - - Dropped 3/4 reports",
-        )
-        .unwrap();
-        SyslogMessage::from_str(
-            "<12>1 2025-11-08T02:24:10.815221698+00:00 ip-172-31-5-8 app 92748 - - Dropped 3/4 reports",
-        )
-        .unwrap();
-        SyslogMessage::from_str(
-            "<12>1 2025-11-08T02:24:10.815+00:00 ip-172-31-5-8 app 92748 - - Dropped 3/4 reports due to staleness"
-        )
-        .unwrap();
-    }
-}

signal-gateway-bin/src/syslog/mod.rs

@@ -0,0 +1,131 @@
+//! Syslog UDP listener for receiving RFC 5424 syslog messages
+
+use conf::Conf;
+use signal_gateway::{Gateway, Level, LogMessage};
+use std::{net::SocketAddr, str::FromStr, sync::Arc};
+use syslog_rfc5424::{SyslogMessage, SyslogSeverity};
+use tokio::net::UdpSocket;
+use tracing::{error, info};
+
+/// Configuration for the syslog UDP listener
+#[derive(Conf, Debug)]
+pub struct SyslogUdpConfig {
+    /// Socket to listen for UDP messages, in syslog RFC 5424 format
+    #[conf(long, env)]
+    pub listen_addr: SocketAddr,
+    /// Structured data ID for tracing metadata (module, file, line) in syslog messages
+    #[conf(long, env, default_value = "tracing-meta@64700")]
+    pub sd_id: String,
+}
+
+impl SyslogUdpConfig {
+    /// Bind a UDP socket and start a background task to handle incoming syslog messages.
+    ///
+    /// Returns a join handle for the background task.
+    pub async fn start_udp_task(
+        &self,
+        gateway: Arc<Gateway>,
+    ) -> std::io::Result<tokio::task::JoinHandle<()>> {
+        let udp_socket = UdpSocket::bind(self.listen_addr).await?;
+        info!("Listening for syslog UDP on {}", self.listen_addr);
+
+        let sd_id = self.sd_id.clone();
+
+        Ok(tokio::task::spawn(async move {
+            let mut buf = vec![0u8; 8192];
+            loop {
+                let Ok((len, _addr)) = udp_socket
+                    .recv_from(&mut buf)
+                    .await
+                    .inspect_err(|err| error!("Error receiving UDP packet: {err}"))
+                else {
+                    continue;
+                };
+
+                let Ok(text) = std::str::from_utf8(&buf[0..len])
+                    .inspect_err(|err| error!("UDP packet was not utf8: {err}"))
+                else {
+                    continue;
+                };
+
+                let Ok(syslog_msg) = SyslogMessage::from_str(text)
+                    .inspect_err(|err| error!("UDP packet was not valid syslog: {err}:\n{text}"))
+                else {
+                    continue;
+                };
+
+                let log_msg = syslog_to_log_message(syslog_msg, &sd_id);
+                gateway.handle_log_message(log_msg).await;
+            }
+        }))
+    }
+}
+
+/// Convert SyslogSeverity to our Level enum
+fn severity_to_level(sev: SyslogSeverity) -> Level {
+    match sev {
+        SyslogSeverity::SEV_EMERG => Level::EMERGENCY,
+        SyslogSeverity::SEV_ALERT => Level::ALERT,
+        SyslogSeverity::SEV_CRIT => Level::CRITICAL,
+        SyslogSeverity::SEV_ERR => Level::ERROR,
+        SyslogSeverity::SEV_WARNING => Level::WARNING,
+        SyslogSeverity::SEV_NOTICE => Level::NOTICE,
+        SyslogSeverity::SEV_INFO => Level::INFO,
+        SyslogSeverity::SEV_DEBUG => Level::DEBUG,
+    }
+}
+
+/// Convert a SyslogMessage to a LogMessage, extracting structured data for tracing metadata
+fn syslog_to_log_message(msg: SyslogMessage, sd_id: &str) -> LogMessage {
+    let level = severity_to_level(msg.severity);
+    let mut builder = LogMessage::builder(level, msg.msg);
+
+    if let Some(ts) = msg.timestamp {
+        builder = builder.timestamp(ts);
+    }
+    if let Some(nanos) = msg.timestamp_nanos {
+        builder = builder.timestamp_nanos(nanos);
+    }
+    if let Some(hostname) = msg.hostname {
+        builder = builder.hostname(hostname);
+    }
+    if let Some(appname) = msg.appname {
+        builder = builder.appname(appname);
+    }
+
+    // Extract tracing metadata from structured data
+    if let Some(sd_element) = msg.sd.find_sdid(sd_id) {
+        if let Some(module) = sd_element.get("module") {
+            builder = builder.module_path(module.clone());
+        }
+        if let Some(file) = sd_element.get("file") {
+            builder = builder.file(file.clone());
+        }
+        if let Some(line) = sd_element.get("line") {
+            builder = builder.line(line.clone());
+        }
+    }
+
+    builder.build()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_syslog_parsing() {
+        SyslogMessage::from_str(
+            "<12>1 2025-11-08T02:24:10.815221698+00:00 ip-172-31-5-8 app 92748 - - Dropped 3/4 reports",
+        )
+        .unwrap();
+        SyslogMessage::from_str(
+            "<12>1 2025-11-08T02:24:10.815221698+00:00 ip-172-31-5-8 app 92748 - - Dropped 3/4 reports",
+        )
+        .unwrap();
+        SyslogMessage::from_str(
+            "<12>1 2025-11-08T02:24:10.815+00:00 ip-172-31-5-8 app 92748 - - Dropped 3/4 reports due to staleness"
+        )
+        .unwrap();
+    }
+}