feat: Update the logger

- Refactors the logger implementation, simplifying the implementation
  and reducing the binary size by ~20kb.
- Adds support for runtime reconfiguration.
- Updates the check for the `Running Firecracker` log to match.
- Updates the default log level to `Info`.

Signed-off-by: Jonathan Woollett-Light <jcawl@amazon.co.uk>

CHANGELOG.md

@@ -57,7 +57,10 @@
   v1.4.0 are available as an improved iteration of the static CPU templates. For
   more information about the transition from static CPU templates to custom CPU
   templates, please refer to [this GitHub discussion](https://github.com/firecracker-microvm/firecracker/discussions/4135).
-
+- Changed default log level from
+  [`Warn`](https://docs.rs/log/latest/log/enum.Level.html#variant.Warn) to
+  [`Info`](https://docs.rs/log/latest/log/enum.Level.html#variant.Info). This
+  results in more logs being output by default.
 ### Fixed
 
 - Fixed a change in behavior of normalize host brand string that breaks

src/api_server/src/request/logger.rs

@@ -2,15 +2,14 @@
 // SPDX-License-Identifier: Apache-2.0
 
 use vmm::logger::{IncMetric, METRICS};
-use vmm::vmm_config::logger_config::LoggerConfig;
 
 use super::super::VmmAction;
 use crate::parsed_request::{Error, ParsedRequest};
 use crate::request::Body;
 
 pub(crate) fn parse_put_logger(body: &Body) -> Result<ParsedRequest, Error> {
     METRICS.put_api_requests.logger_count.inc();
-    let res = serde_json::from_slice::<LoggerConfig>(body.raw());
+    let res = serde_json::from_slice::<vmm::logger::LoggerConfig>(body.raw());
     let config = res.map_err(|err| {
         METRICS.put_api_requests.logger_fails.inc();
         err
@@ -22,41 +21,43 @@ pub(crate) fn parse_put_logger(body: &Body) -> Result<ParsedRequest, Error> {
 mod tests {
     use std::path::PathBuf;
 
-    use vmm::vmm_config::logger_config::LoggerLevel;
+    use vmm::logger::{LevelFilter, LoggerConfig};
 
     use super::*;
     use crate::parsed_request::tests::vmm_action_from_request;
 
     #[test]
     fn test_parse_put_logger_request() {
         let body = r#"{
-            "log_path": "log",
-            "level": "Warning",
-            "show_level": false,
-            "show_log_origin": false
-        }"#;
+                "log_path": "log",
+                "level": "Warning",
+                "show_level": false,
+                "show_log_origin": false
+              }"#;
+
         let expected_config = LoggerConfig {
-            log_path: PathBuf::from("log"),
-            level: LoggerLevel::Warning,
-            show_level: false,
-            show_log_origin: false,
+            log_path: Some(PathBuf::from("log")),
+            level: Some(LevelFilter::Warn),
+            show_level: Some(false),
+            show_log_origin: Some(false),
         };
         assert_eq!(
             vmm_action_from_request(parse_put_logger(&Body::new(body)).unwrap()),
             VmmAction::ConfigureLogger(expected_config)
         );
 
         let body = r#"{
-            "log_path": "log",
-            "level": "DEBUG",
-            "show_level": false,
-            "show_log_origin": false
-        }"#;
+                "log_path": "log",
+                "level": "DEBUG",
+                "show_level": false,
+                "show_log_origin": false
+              }"#;
+
         let expected_config = LoggerConfig {
-            log_path: PathBuf::from("log"),
-            level: LoggerLevel::Debug,
-            show_level: false,
-            show_log_origin: false,
+            log_path: Some(PathBuf::from("log")),
+            level: Some(LevelFilter::Debug),
+            show_level: Some(false),
+            show_log_origin: Some(false),
         };
         assert_eq!(
             vmm_action_from_request(parse_put_logger(&Body::new(body)).unwrap()),

src/api_server/swagger/firecracker.yaml

@@ -983,8 +983,8 @@ definitions:
       level:
         type: string
         description: Set the level. The possible values are case-insensitive.
-        enum: [Error, Warning, Info, Debug]
-        default: Warning
+        enum: [Error, Warning, Info, Debug, Trace, Off]
+        default: Info
       log_path:
         type: string
         description: Path to the named pipe or file for the human readable log output.

src/firecracker/Cargo.toml

@@ -16,6 +16,7 @@ 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"