fix(shutdown): emit VectorStopped after topology drains (#25083)

* move VectorStopped event

* add changelog

* Add VectorStopping event

* Update changelog.d/24532_vector_stopped_log_ordering.fix.md

* Apply suggestion from @pront

---------

Co-authored-by: Pavlos Rontidis <pavlos.rontidis@gmail.com>

Author: tronboto

changelog.d/24532_vector_stopped_log_ordering.fix.md

@@ -0,0 +1,5 @@
+Fixed log message ordering on shutdown where `Vector has stopped.` was logged before components had finished draining, causing confusing output interleaved with `Waiting on running components` messages.
+
+A new `VectorStoppping` event was added in the place of the `VectorStopped` event.
+
+authors: tronboto

src/app.rs

@@ -28,7 +28,9 @@ use crate::{
     config::{self, ComponentConfig, ComponentType, Config, ConfigPath},
     extra_context::ExtraContext,
     heartbeat,
-    internal_events::{VectorConfigLoadError, VectorQuit, VectorStarted, VectorStopped},
+    internal_events::{
+        VectorConfigLoadError, VectorQuit, VectorStarted, VectorStopped, VectorStopping,
+    },
     signal::{SignalHandler, SignalPair, SignalRx, SignalTo},
     topology::{
         ReloadOutcome, RunningTopology, SharedTopologyController, ShutdownErrorReceiver,
@@ -493,16 +495,19 @@ impl FinishedApplication {
     }
 
     async fn stop(topology_controller: TopologyController, mut signal_rx: SignalRx) -> ExitStatus {
-        emit!(VectorStopped);
+        emit!(VectorStopping);
         tokio::select! {
-            _ = topology_controller.stop() => ExitStatus::from_raw({
-                #[cfg(windows)]
-                {
-                    exitcode::OK as u32
-                }
-                #[cfg(unix)]
-                exitcode::OK
-            }), // Graceful shutdown finished
+            _ = topology_controller.stop() => {
+                emit!(VectorStopped);
+                ExitStatus::from_raw({
+                    #[cfg(windows)]
+                    {
+                        exitcode::OK as u32
+                    }
+                    #[cfg(unix)]
+                    exitcode::OK
+                })
+            }, // Graceful shutdown finished
             _ = signal_rx.recv() => Self::quit(),
         }
     }

src/internal_events/process.rs

@@ -38,6 +38,18 @@ impl InternalEvent for VectorReloaded<'_> {
     }
 }
 
+#[derive(Debug, NamedInternalEvent)]
+pub struct VectorStopping;
+
+impl InternalEvent for VectorStopping {
+    fn emit(self) {
+        info!(
+            target: "vector",
+            message = "Vector is stopping.",
+        );
+    }
+}
+
 #[derive(Debug, NamedInternalEvent)]
 pub struct VectorStopped;