Implement rolling logfile output (#15)

.gitignore

@@ -1,4 +1,5 @@
 .sqlx/
+logs/
 clubfridge.db
 
 # Generated by Cargo

Cargo.toml

@@ -20,6 +20,7 @@ serde_json = "=1.0.138"
 sqlx = { version = "=0.8.3", features = ["runtime-tokio", "sqlite"] }
 tokio = { version = "=1.43.0", features = ["time"] }
 tracing = "=0.1.41"
+tracing-appender = "=0.2.3"
 tracing-subscriber = "=0.3.19"
 ulid = "=1.2.0"
 vereinsflieger = "=0.7.0"

src/logging.rs

@@ -0,0 +1,62 @@
+use tracing_subscriber::filter::Targets;
+use tracing_subscriber::layer::SubscriberExt;
+use tracing_subscriber::util::SubscriberInitExt;
+use tracing_subscriber::Layer;
+
+const DEFAULT_TARGETS: &str = "warn,clubfridge_neo=debug";
+
+pub fn init() -> anyhow::Result<()> {
+    let targets = targets_from_env();
+
+    let stdout_layer = tracing_subscriber::fmt::layer()
+        .compact()
+        .with_filter(targets.clone());
+
+    let file_appender = tracing_appender::rolling::Builder::new()
+        .rotation(tracing_appender::rolling::Rotation::DAILY)
+        .filename_prefix("clubfridge-neo")
+        .filename_suffix("log")
+        .max_log_files(7)
+        .build("logs")?;
+
+    let logfile_layer = tracing_subscriber::fmt::layer()
+        .compact()
+        .with_ansi(false)
+        .with_writer(file_appender)
+        .with_filter(targets);
+
+    Ok(tracing_subscriber::registry()
+        .with(stdout_layer)
+        .with(logfile_layer)
+        .try_init()?)
+}
+
+fn targets_from_env() -> Targets {
+    let targets = match std::env::var("RUST_LOG") {
+        Ok(value) => value,
+        Err(std::env::VarError::NotPresent) => return default_targets(),
+        Err(err) => {
+            eprintln!("Ignoring `RUST_LOG`: {err}");
+            return default_targets();
+        }
+    };
+
+    targets.parse().unwrap_or_else(|err| {
+        eprintln!("Ignoring `RUST_LOG={targets:?}`: {err}");
+        default_targets()
+    })
+}
+
+fn default_targets() -> Targets {
+    DEFAULT_TARGETS.parse().unwrap()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_default_targets_does_not_panic() {
+        default_targets();
+    }
+}

src/main.rs

@@ -1,4 +1,5 @@
 mod database;
+mod logging;
 mod popup;
 mod running;
 mod setup;
@@ -10,7 +11,7 @@ mod vereinsflieger;
 use crate::state::{ClubFridge, Options};
 
 pub fn main() -> anyhow::Result<()> {
-    tracing_subscriber::fmt::init();
+    logging::init()?;
 
     let options = <Options as clap::Parser>::parse();