From e54ca7e30ac94950f1e5dffe0fb1b3cc940e9515 Mon Sep 17 00:00:00 2001
From: Christian Schwarz <me@cschwarz.com>
Date: Thu, 9 Nov 2023 16:31:20 +0000
Subject: [PATCH] logging: add ability to log to stderr

---
 control_plane/src/bin/attachment_service.rs |  1 +
 libs/utils/src/logging.rs                   | 15 ++++++++++++++-
 pageserver/src/bin/pageserver.rs            |  6 +++++-
 safekeeper/src/bin/safekeeper.rs            |  1 +
 storage_broker/src/bin/storage_broker.rs    |  1 +
 5 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/control_plane/src/bin/attachment_service.rs b/control_plane/src/bin/attachment_service.rs
index 3205703c7d..f052a1b5ff 100644
--- a/control_plane/src/bin/attachment_service.rs
+++ b/control_plane/src/bin/attachment_service.rs
@@ -268,6 +268,7 @@ async fn main() -> anyhow::Result<()> {
     logging::init(
         LogFormat::Plain,
         logging::TracingErrorLayerEnablement::Disabled,
+        logging::Output::Stdout,
     )?;
 
     let args = Cli::parse();
diff --git a/libs/utils/src/logging.rs b/libs/utils/src/logging.rs
index 502e02dc71..2f09c2f3ea 100644
--- a/libs/utils/src/logging.rs
+++ b/libs/utils/src/logging.rs
@@ -66,9 +66,17 @@ pub enum TracingErrorLayerEnablement {
     EnableWithRustLogFilter,
 }
 
+/// Where the logging should output to.
+#[derive(Clone, Copy)]
+pub enum Output {
+    Stdout,
+    Stderr,
+}
+
 pub fn init(
     log_format: LogFormat,
     tracing_error_layer_enablement: TracingErrorLayerEnablement,
+    output: Output,
 ) -> anyhow::Result<()> {
     // We fall back to printing all spans at info-level or above if
     // the RUST_LOG environment variable is not set.
@@ -85,7 +93,12 @@ pub fn init(
         let log_layer = tracing_subscriber::fmt::layer()
             .with_target(false)
             .with_ansi(false)
-            .with_writer(std::io::stdout);
+            .with_writer(move || -> Box<dyn std::io::Write> {
+                match output {
+                    Output::Stdout => Box::new(std::io::stdout()),
+                    Output::Stderr => Box::new(std::io::stderr()),
+                }
+            });
         let log_layer = match log_format {
             LogFormat::Json => log_layer.json().boxed(),
             LogFormat::Plain => log_layer.boxed(),
diff --git a/pageserver/src/bin/pageserver.rs b/pageserver/src/bin/pageserver.rs
index 5b0c140d00..f971b0a88d 100644
--- a/pageserver/src/bin/pageserver.rs
+++ b/pageserver/src/bin/pageserver.rs
@@ -103,7 +103,11 @@ fn main() -> anyhow::Result<()> {
     } else {
         TracingErrorLayerEnablement::Disabled
     };
-    logging::init(conf.log_format, tracing_error_layer_enablement)?;
+    logging::init(
+        conf.log_format,
+        tracing_error_layer_enablement,
+        logging::Output::Stdout,
+    )?;
 
     // mind the order required here: 1. logging, 2. panic_hook, 3. sentry.
     // disarming this hook on pageserver, because we never tear down tracing.
diff --git a/safekeeper/src/bin/safekeeper.rs b/safekeeper/src/bin/safekeeper.rs
index 2e54380471..0b5bb22c8b 100644
--- a/safekeeper/src/bin/safekeeper.rs
+++ b/safekeeper/src/bin/safekeeper.rs
@@ -202,6 +202,7 @@ async fn main() -> anyhow::Result<()> {
     logging::init(
         LogFormat::from_config(&args.log_format)?,
         logging::TracingErrorLayerEnablement::Disabled,
+        logging::Output::Stdout,
     )?;
     logging::replace_panic_hook_with_tracing_panic_hook().forget();
     info!("version: {GIT_VERSION}");
diff --git a/storage_broker/src/bin/storage_broker.rs b/storage_broker/src/bin/storage_broker.rs
index 5ce24a6a42..9f81ac6cac 100644
--- a/storage_broker/src/bin/storage_broker.rs
+++ b/storage_broker/src/bin/storage_broker.rs
@@ -434,6 +434,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
     logging::init(
         LogFormat::from_config(&args.log_format)?,
         logging::TracingErrorLayerEnablement::Disabled,
+        logging::Output::Stdout,
     )?;
     logging::replace_panic_hook_with_tracing_panic_hook().forget();
     // initialize sentry if SENTRY_DSN is provided