From 3d0774772e49f2800a63233bc9807d7118aae019 Mon Sep 17 00:00:00 2001
From: Jonathan Woollett-Light <jcawl@amazon.co.uk>
Date: Tue, 26 Sep 2023 10:39:53 +0100
Subject: [PATCH] fix: Logger initialization function

Adds a logger initialization function that allows removing the `log`
dependencies.

Signed-off-by: Jonathan Woollett-Light <jcawl@amazon.co.uk>
---
 Cargo.lock                    |  1 -
 src/firecracker/Cargo.toml    |  1 -
 src/firecracker/src/main.rs   |  5 ++---
 src/vmm/src/logger/logging.rs | 10 ++++++++++
 src/vmm/src/logger/mod.rs     |  4 ++--
 5 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 059bbe5127c..ba2ea6c69e2 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -538,7 +538,6 @@ dependencies = [
  "displaydoc",
  "event-manager",
  "libc",
- "log",
  "regex",
  "seccompiler",
  "serde",
diff --git a/src/firecracker/Cargo.toml b/src/firecracker/Cargo.toml
index c3e5e9092e6..105ff1b2f95 100644
--- a/src/firecracker/Cargo.toml
+++ b/src/firecracker/Cargo.toml
@@ -16,7 +16,6 @@ bench = false
 displaydoc = "0.2.4"
 event-manager = "0.3.0"
 libc = "0.2.148"
-log = "0.4.20"
 serde_json = "1.0.107"
 thiserror = "1.0.49"
 timerfd = "1.5.0"
diff --git a/src/firecracker/src/main.rs b/src/firecracker/src/main.rs
index 2539ae50b52..b39ef1cbf67 100644
--- a/src/firecracker/src/main.rs
+++ b/src/firecracker/src/main.rs
@@ -43,7 +43,7 @@ const MMDS_CONTENT_ARG: &str = "metadata";
 #[derive(Debug, thiserror::Error, displaydoc::Display)]
 enum MainError {
     /// Failed to set the logger: {0}
-    SetLogger(log::SetLoggerError),
+    SetLogger(vmm::logger::LoggerInitError),
     /// Failed to register signal handlers: {0}
     RegisterSignalHandlers(#[source] utils::errno::Error),
     /// Arguments parsing error: {0} \n\nFor more information try --help.
@@ -103,8 +103,7 @@ fn main() -> ExitCode {
 
 fn main_exec() -> Result<(), MainError> {
     // Initialize the logger.
-    log::set_logger(&LOGGER).map_err(MainError::SetLogger)?;
-    log::set_max_level(vmm::logger::DEFAULT_LEVEL);
+    LOGGER.init().map_err(MainError::SetLogger)?;
     info!("Running Firecracker v{FIRECRACKER_VERSION}");
 
     register_signal_handlers().map_err(MainError::RegisterSignalHandlers)?;
diff --git a/src/vmm/src/logger/logging.rs b/src/vmm/src/logger/logging.rs
index 04f6fb61181..fb9a27eacc1 100644
--- a/src/vmm/src/logger/logging.rs
+++ b/src/vmm/src/logger/logging.rs
@@ -36,12 +36,22 @@ pub static LOGGER: Logger = Logger(Mutex::new(LoggerConfiguration {
     },
 }));
 
+/// Error type for [`Logger::init`].
+pub type LoggerInitError = log::SetLoggerError;
+
 /// Error type for [`Logger::update`].
 #[derive(Debug, thiserror::Error)]
 #[error("Failed to open target file: {0}")]
 pub struct LoggerUpdateError(pub std::io::Error);
 
 impl Logger {
+    /// Initialize the logger.
+    pub fn init(&'static self) -> Result<(), LoggerInitError> {
+        log::set_logger(self)?;
+        log::set_max_level(DEFAULT_LEVEL);
+        Ok(())
+    }
+
     /// Applies the given logger configuration the logger.
     pub fn update(&self, config: LoggerConfig) -> Result<(), LoggerUpdateError> {
         let mut guard = self.0.lock().unwrap();
diff --git a/src/vmm/src/logger/mod.rs b/src/vmm/src/logger/mod.rs
index 31272585e32..42cbb21e735 100644
--- a/src/vmm/src/logger/mod.rs
+++ b/src/vmm/src/logger/mod.rs
@@ -11,8 +11,8 @@ mod metrics;
 
 pub use log::{debug, error, info, log_enabled, trace, warn, Level};
 pub use logging::{
-    LevelFilter, LevelFilterFromStrError, LoggerConfig, LoggerUpdateError, DEFAULT_INSTANCE_ID,
-    DEFAULT_LEVEL, INSTANCE_ID, LOGGER,
+    LevelFilter, LevelFilterFromStrError, LoggerConfig, LoggerInitError, LoggerUpdateError,
+    DEFAULT_INSTANCE_ID, DEFAULT_LEVEL, INSTANCE_ID, LOGGER,
 };
 #[cfg(target_arch = "aarch64")]
 pub use metrics::RTCDeviceMetrics;