logging: Make output bare of level/target/fields (#30)

Cargo.toml

@@ -27,7 +27,7 @@ reqwest = { version = "0.11", features = ["blocking", "json"] }
 try-guard = "0.2.0"
 clap = { version = "4.4", features = ["derive"] }
 urlencoding = "2.1.3"
-nix_rs = { version = "0.1.7", features = ["ssr"] }
+nix_rs = { version = "0.1.8", features = ["ssr"] }
 tracing-subscriber = { version = "0.3.17", features = ["env-filter"] }
 tracing = "0.1.37"
 

src/lib.rs

@@ -1,17 +1,18 @@
 pub mod cli;
 pub mod config;
 pub mod github;
+pub mod logging;
 pub mod nix;
 
-use std::{collections::HashSet, io};
+use std::collections::HashSet;
 
 use cli::CliArgs;
 use colored::Colorize;
 use nix::{
     devour_flake::{DevourFlakeOutput, DrvOut},
     url::FlakeUrl,
 };
-use tracing::{instrument, Level};
+use tracing::instrument;
 
 /// Run nixci on the given [CliArgs], returning the built outputs in sorted order.
 #[instrument(name = "nixci", skip(args))]
@@ -51,21 +52,3 @@ async fn nixci_subflake(
     }
     Ok(outs)
 }
-
-pub fn setup_logging(verbose: bool) {
-    let env_filter = if verbose {
-        "nixci=debug,nix_rs=debug"
-    } else {
-        "nixci=info,nix_rs=info"
-    };
-    let builder = tracing_subscriber::fmt()
-        .with_writer(io::stderr)
-        .with_max_level(Level::INFO)
-        .with_env_filter(env_filter)
-        .compact();
-    if !verbose {
-        builder.without_time().init()
-    } else {
-        builder.init()
-    }
-}

src/logging.rs

@@ -0,0 +1,53 @@
+use std::fmt;
+use std::io;
+
+use tracing::{Event, Level, Subscriber};
+use tracing_subscriber::fmt::format;
+use tracing_subscriber::{
+    fmt::{FmtContext, FormatEvent, FormatFields},
+    registry::LookupSpan,
+};
+
+/// A [tracing_subscriber] event formatter that suppresses everything but the
+/// log message.
+///
+/// Level/target are displayed for non-INFO messages.
+struct BareFormatter;
+
+impl<S, N> FormatEvent<S, N> for BareFormatter
+where
+    S: Subscriber + for<'a> LookupSpan<'a>,
+    N: for<'a> FormatFields<'a> + 'static,
+{
+    fn format_event(
+        &self,
+        ctx: &FmtContext<'_, S, N>,
+        mut writer: format::Writer<'_>,
+        event: &Event<'_>,
+    ) -> fmt::Result {
+        let metadata = event.metadata();
+        if metadata.level() != &Level::INFO {
+            write!(&mut writer, "{} {}: ", metadata.level(), metadata.target())?;
+        }
+        ctx.field_format().format_fields(writer.by_ref(), event)?;
+        writeln!(writer)
+    }
+}
+
+pub fn setup_logging(verbose: bool) {
+    let env_filter = if verbose {
+        "nixci=debug,nix_rs=debug"
+    } else {
+        "nixci=info,nix_rs=info"
+    };
+    let builder = tracing_subscriber::fmt()
+        .with_writer(io::stderr)
+        .with_max_level(Level::INFO)
+        .with_env_filter(env_filter);
+
+    if !verbose {
+        builder.event_format(BareFormatter).init();
+    } else {
+        builder.init()
+    }
+}

src/main.rs

@@ -5,7 +5,7 @@ use nixci::cli;
 #[tokio::main]
 async fn main() -> Result<()> {
     let args = cli::CliArgs::parse();
-    nixci::setup_logging(args.verbose);
+    nixci::logging::setup_logging(args.verbose);
     let _outs = nixci::nixci(args).await?;
     Ok(())
 }

tests/integration_test.rs

@@ -10,7 +10,7 @@ mod integration_test {
 
     #[ctor::ctor]
     fn init() {
-        nixci::setup_logging(true);
+        nixci::logging::setup_logging(true);
     }
 
     #[tokio::test]