feat: add debug flag

for #454

crates/youki/src/logger.rs

@@ -4,6 +4,7 @@ use anyhow::{bail, Context, Result};
 use std::fs::OpenOptions;
 use std::io::Write;
 use std::path::PathBuf;
+use std::str::FromStr;
 
 /// If in debug mode, default level is debug to get maximum logging
 #[cfg(debug_assertions)]
@@ -19,12 +20,18 @@ const LOG_FORMAT_JSON: &str = "json";
 /// Initialize the logger, must be called before accessing the logger
 /// Multiple parts might call this at once, but the actual initialization
 /// is done only once due to use of OnceCell
-pub fn init(log_file: Option<PathBuf>, log_format: Option<String>) -> Result<()> {
+pub fn init(log_debug_flag: bool, log_file: Option<PathBuf>, log_format: Option<String>) -> Result<()> {
     let formatter = match log_format.as_deref() {
         None | Some(LOG_FORMAT_TEXT) => text_write,
         Some(LOG_FORMAT_JSON) => json_write,
         Some(unknown) => bail!("unknown log format: {}", unknown),
     };
+    let from_env_log_level = env_logger::Env::new().filter("YOUKI_LOG_LEVEL");
+    let log_level = if log_debug_flag {
+        "debug"
+    } else {
+        DEFAULT_LOG_LEVEL
+    };
     let target = if let Some(log_file) = log_file {
         let file = OpenOptions::new()
             .create(true)
@@ -36,12 +43,12 @@ pub fn init(log_file: Option<PathBuf>, log_format: Option<String>) -> Result<()>
     } else {
         env_logger::Target::Stderr
     };
-    env_logger::Builder::from_env(
-        env_logger::Env::default().filter_or("YOUKI_LOG_LEVEL", DEFAULT_LOG_LEVEL),
-    )
-    .format(formatter)
-    .target(target)
-    .init();
+    env_logger::Builder::new()
+        .parse_env(from_env_log_level)
+        .filter_level(FromStr::from_str(log_level).unwrap())
+        .format(formatter)
+        .target(target)
+        .init();
 
     Ok(())
 }

crates/youki/src/main.rs

@@ -38,6 +38,11 @@ use nix::unistd::getuid;
 #[derive(Parser, Debug)]
 #[clap(version = crate_version!(), author = "youki team")]
 struct Opts {
+    // I don't know how to get the log level when the --debug flag is not set (I want to show some default values on the help page when the options are not set)
+    // Example: '--debug     change log level to debug. (default: "warn")'
+    /// change log level to debug.
+    #[clap(long)]
+    debug: bool,
     #[clap(short, long)]
     log: Option<PathBuf>,
     #[clap(long)]
@@ -104,7 +109,7 @@ fn main() -> Result<()> {
 
     let opts = Opts::parse();
 
-    if let Err(e) = crate::logger::init(opts.log, opts.log_format) {
+    if let Err(e) = crate::logger::init(opts.debug, opts.log, opts.log_format) {
         eprintln!("log init failed: {:?}", e);
     }