Add the date when the node was started to the name of the logfile.

This makes it easier to delete old logs
Create a symlink to the latest log file.

Author: ulrichard

src/lib.rs

@@ -417,8 +417,12 @@ impl Builder {
 		let config = Arc::new(self.config.read().unwrap().clone());
 
 		// Initialize the Logger
-		let log_file_path = format!("{}/ldk_node.log", config.storage_dir_path);
-		let logger = Arc::new(FilesystemLogger::new(log_file_path, config.log_level));
+		let log_file_path = format!(
+			"{}/logs/ldk_node_{}.log",
+			config.storage_dir_path,
+			chrono::offset::Local::now().format("%Y_%m_%d")
+		);
+		let logger = Arc::new(FilesystemLogger::new(log_file_path.clone(), config.log_level));
 
 		// Initialize the on-chain wallet and chain access
 		let seed_bytes = match &*self.entropy_source_config.read().unwrap() {

src/logger.rs

@@ -7,6 +7,7 @@ use lightning::util::ser::Writer;
 use chrono::Utc;
 
 use std::fs;
+use std::os::unix::fs::symlink;
 use std::path::Path;
 
 pub(crate) struct FilesystemLogger {
@@ -18,7 +19,26 @@ impl FilesystemLogger {
 	pub(crate) fn new(file_path: String, level: Level) -> Self {
 		if let Some(parent_dir) = Path::new(&file_path).parent() {
 			fs::create_dir_all(parent_dir).expect("Failed to create log parent directory");
+
+			// make sure the file exists, so that the symlink has something to point to.
+			fs::OpenOptions::new()
+				.create(true)
+				.append(true)
+				.open(file_path.clone())
+				.expect("Failed to open log file");
+
+			// Create a symlink to the current log file, with prior cleanup
+			let log_file_symlink = parent_dir.join("ldk_node_latest.log");
+			if log_file_symlink.as_path().exists() && log_file_symlink.as_path().is_symlink() {
+				fs::remove_file(&log_file_symlink)
+					.expect("Failed to remove an old symlink for the log file");
+			}
+			symlink(&file_path, &log_file_symlink).expect(&format!(
+				"Failed to create symlink for the log file: {:?}",
+				log_file_symlink
+			));
 		}
+
 		Self { file_path, level }
 	}
 }

src/test/functional_tests.rs

@@ -310,6 +310,9 @@ fn start_stop_reinit() {
 	node.sync_wallets().unwrap();
 	assert_eq!(node.onchain_balance().unwrap().get_spendable(), expected_amount.to_sat());
 
+	let log_file_symlink = format!("{}/logs/ldk_node_latest.log", config.storage_dir_path);
+	assert!(std::path::Path::new(&log_file_symlink).is_symlink());
+
 	node.stop().unwrap();
 	assert_eq!(node.stop(), Err(Error::NotRunning));