Harden LA publishers and add multi-relay guide

crates/ec-node/src/main.rs

@@ -5116,20 +5116,33 @@ async fn control_resolve(args: ControlResolveArgs) -> Result<()> {
     ))
 }
 
-fn select_relay_transport_for_web(
-    transports: &[StreamTransportDescriptor],
-) -> Option<(String, String, String)> {
-    for transport in transports {
-        if let StreamTransportDescriptor::RelayMoq {
-            url,
-            broadcast_name,
-            track_name,
-        } = transport
-        {
-            return Some((url.clone(), broadcast_name.clone(), track_name.clone()));
-        }
-    }
-    None
+fn relay_transports_for_web(transports: &[StreamTransportDescriptor]) -> Vec<WebStreamRelay> {
+    transports
+        .iter()
+        .filter_map(|transport| {
+            if let StreamTransportDescriptor::RelayMoq {
+                url,
+                broadcast_name,
+                track_name,
+            } = transport
+            {
+                Some(WebStreamRelay {
+                    relay_url: url.clone(),
+                    broadcast_name: broadcast_name.clone(),
+                    track_name: track_name.clone(),
+                })
+            } else {
+                None
+            }
+        })
+        .collect()
+}
+
+#[derive(Debug, Clone, serde::Serialize)]
+struct WebStreamRelay {
+    relay_url: String,
+    broadcast_name: String,
+    track_name: String,
 }
 
 #[derive(Debug, serde::Serialize)]
@@ -5139,6 +5152,7 @@ struct WebStreamUpsertReq<'a> {
     relay_url: &'a str,
     broadcast_name: &'a str,
     track_name: &'a str,
+    relays: &'a [WebStreamRelay],
     expires_ms: u64,
 }
 
@@ -5207,11 +5221,11 @@ async fn control_bridge_web(args: ControlBridgeWebArgs) -> Result<()> {
             }
         }
 
-        let Some((relay_url, broadcast_name, track_name)) =
-            select_relay_transport_for_web(&announcement.transports)
-        else {
+        let relays = relay_transports_for_web(&announcement.transports);
+        if relays.is_empty() {
             continue;
-        };
+        }
+        let primary_relay = &relays[0];
 
         if last_upserted_unix_ms
             .get(&stream_id)
@@ -5224,9 +5238,10 @@ async fn control_bridge_web(args: ControlBridgeWebArgs) -> Result<()> {
         let payload = WebStreamUpsertReq {
             stream_id: &stream_id,
             title: &announcement.stream.title,
-            relay_url: &relay_url,
-            broadcast_name: &broadcast_name,
-            track_name: &track_name,
+            relay_url: &primary_relay.relay_url,
+            broadcast_name: &primary_relay.broadcast_name,
+            track_name: &primary_relay.track_name,
+            relays: &relays,
             expires_ms: now_unix_ms().saturating_add(ttl_ms),
         };
 
@@ -5253,8 +5268,9 @@ async fn control_bridge_web(args: ControlBridgeWebArgs) -> Result<()> {
         last_upserted_unix_ms.insert(stream_id.clone(), announcement.updated_unix_ms);
         tracing::info!(
             stream = %stream_id,
-            relay = %relay_url,
-            broadcast = %broadcast_name,
+            relay = %primary_relay.relay_url,
+            broadcast = %primary_relay.broadcast_name,
+            relay_count = relays.len(),
             "web stream upserted"
         );
         if args.once {
@@ -6853,6 +6869,7 @@ async fn wt_publish(args: WtPublishArgs) -> Result<()> {
 
     cmd.stdout(Stdio::piped());
     cmd.stderr(Stdio::inherit());
+    cmd.kill_on_drop(true);
 
     tracing::info!(input=%args.input, "spawning ffmpeg");
     let mut child = cmd.spawn().context("failed to spawn ffmpeg")?;
@@ -6990,6 +7007,7 @@ async fn nbc_wt_publish(args: NbcWtPublishArgs) -> Result<()> {
     cmd.stdin(Stdio::piped());
     cmd.stdout(Stdio::piped());
     cmd.stderr(Stdio::inherit());
+    cmd.kill_on_drop(true);
 
     tracing::info!(
         source_url = %args.source_url,