Add runc-compatible json logger

Cargo.toml

@@ -22,6 +22,10 @@ bollard = "0.16"
 rustix = { version = "0.38", features = ["fs", "stdio", "termios", "process", "thread"] }
 bitflags = "2"
 once_cell = "1"
+humantime = "2"
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+
 aya = { git = "https://github.com/aya-rs/aya.git" }
 
 [build-dependencies]

src/main.rs

@@ -3,6 +3,7 @@ mod cli;
 mod dev;
 mod docker;
 mod hotplug;
+mod runc;
 mod util;
 
 use cli::Action;

src/runc/log.rs

@@ -0,0 +1,56 @@
+use std::io::{BufWriter, Write};
+use std::sync::Mutex;
+use std::time::SystemTime;
+
+use log::{Level, Log};
+use serde::Serialize;
+
+#[derive(Serialize)]
+struct Message {
+    level: &'static str,
+    msg: String,
+    time: String,
+}
+
+fn map_log_level(level: Level) -> &'static str {
+    match level {
+        Level::Error => "error",
+        Level::Warn => "warning",
+        Level::Info => "info",
+        Level::Debug => "debug",
+        Level::Trace => "trace",
+    }
+}
+
+/// JSON logger compatible with logrus (the logging library used by runc and many go projects).
+pub struct JsonLogger {
+    target: Mutex<BufWriter<Box<dyn Write + Send>>>,
+}
+
+impl JsonLogger {
+    pub fn new(target: Box<dyn Write + Send>) -> Self {
+        Self {
+            target: Mutex::new(BufWriter::new(target)),
+        }
+    }
+}
+
+impl Log for JsonLogger {
+    fn enabled(&self, _: &log::Metadata) -> bool {
+        true
+    }
+
+    fn log(&self, record: &log::Record) {
+        let msg = Message {
+            level: map_log_level(record.level()),
+            msg: record.args().to_string(),
+            time: humantime::format_rfc3339_seconds(SystemTime::now()).to_string(),
+        };
+
+        let mut target = self.target.lock().unwrap();
+        let _ = serde_json::to_writer(&mut *target, &msg);
+        let _ = target.flush();
+    }
+
+    fn flush(&self) {}
+}

src/runc/mod.rs

@@ -0,0 +1 @@
+pub mod log;