vm-monitor: Improve error display (#10542)

Logging errors with the debug format specifier causes multi-line errors,
which are sometimes a pain to deal with. Instead, we should use anyhow's
alternate display format, which shows the same information on a single
line.

Also adjusted a couple of error messages that were stale.

Fixes neondatabase/cloud#14710.

libs/vm_monitor/src/filecache.rs

@@ -177,8 +177,8 @@ impl FileCacheState {
         crate::spawn_with_cancel(
             token,
             |res| {
-                if let Err(error) = res {
-                    error!(%error, "postgres error")
+                if let Err(e) = res {
+                    error!(error = format_args!("{e:#}"), "postgres error");
                 }
             },
             conn,
@@ -205,7 +205,7 @@ impl FileCacheState {
         {
             Ok(rows) => Ok(rows),
             Err(e) => {
-                error!(error = ?e, "postgres error: {e} -> retrying");
+                error!(error = format_args!("{e:#}"), "postgres error -> retrying");
 
                 let client = FileCacheState::connect(&self.conn_str, self.token.clone())
                     .await

libs/vm_monitor/src/lib.rs

@@ -191,15 +191,12 @@ async fn start_monitor(
     .await;
     let mut monitor = match monitor {
         Ok(Ok(monitor)) => monitor,
-        Ok(Err(error)) => {
-            error!(?error, "failed to create monitor");
+        Ok(Err(e)) => {
+            error!(error = format_args!("{e:#}"), "failed to create monitor");
             return;
         }
         Err(_) => {
-            error!(
-                ?timeout,
-                "creating monitor timed out (probably waiting to receive protocol range)"
-            );
+            error!(?timeout, "creating monitor timed out");
             return;
         }
     };
@@ -207,6 +204,9 @@ async fn start_monitor(
 
     match monitor.run().await {
         Ok(()) => info!("monitor was killed due to new connection"),
-        Err(e) => error!(error = ?e, "monitor terminated unexpectedly"),
+        Err(e) => error!(
+            error = format_args!("{e:#}"),
+            "monitor terminated unexpectedly"
+        ),
     }
 }

libs/vm_monitor/src/runner.rs

@@ -370,12 +370,16 @@ impl Runner {
                 }),
             InboundMsgKind::InvalidMessage { error } => {
                 warn!(
-                    %error, id, "received notification of an invalid message we sent"
+                    error = format_args!("{error:#}"),
+                    id, "received notification of an invalid message we sent"
                 );
                 Ok(None)
             }
             InboundMsgKind::InternalError { error } => {
-                warn!(error, id, "agent experienced an internal error");
+                warn!(
+                    error = format_args!("{error:#}"),
+                    id, "agent experienced an internal error"
+                );
                 Ok(None)
             }
             InboundMsgKind::HealthCheck {} => {
@@ -476,7 +480,7 @@ impl Runner {
                                         // gives the outermost cause, and the debug impl
                                         // pretty-prints the error, whereas {:#} contains all the
                                         // causes, but is compact (no newlines).
-                                        warn!(error = format!("{e:#}"), "error handling message");
+                                        warn!(error = format_args!("{e:#}"), "error handling message");
                                         OutboundMsg::new(
                                             OutboundMsgKind::InternalError {
                                                 error: e.to_string(),
@@ -492,7 +496,7 @@ impl Runner {
                                     .context("failed to send message")?;
                             }
                             Err(e) => warn!(
-                                error = format!("{e}"),
+                                error = format_args!("{e:#}"),
                                 msg = ?msg,
                                 "received error message"
                             ),