Merge branch 'refactor-main' into 'next'

return ExitCode instead of using panic or exit

See merge request famedly/conduit!639

src/error.rs

@@ -0,0 +1,64 @@
+//! Error handling facilities
+
+use std::{fmt, iter};
+
+use thiserror::Error;
+
+/// Wraps any [`Error`][e] type so that [`Display`][d] includes its [sources][s]
+///
+/// [e]: std::error::Error
+/// [d]: fmt::Display
+/// [s]: std::error::Error::source
+pub struct Chain<'a>(pub &'a dyn std::error::Error);
+
+impl fmt::Display for Chain<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.0)?;
+
+        let mut source = self.0.source();
+
+        source
+            .into_iter()
+            .chain(iter::from_fn(|| {
+                source = source.and_then(std::error::Error::source);
+                source
+            }))
+            .try_for_each(|source| write!(f, ": {source}"))
+    }
+}
+
+/// Top-level errors
+// Missing docs are allowed here since that kind of information should be
+// encoded in the error messages themselves anyway.
+#[allow(missing_docs)]
+#[derive(Error, Debug)]
+pub enum CliError {
+    #[error(
+        "the `CONDUIT_CONFIG` environment variable must either be set to a configuration file path \
+        or set to an empty string to force configuration through environment variables"
+    )]
+    ConfigPathUnset,
+
+    #[error("invalid configuration")]
+    ConfigInvalid(#[from] figment::Error),
+
+    // Upstream's documentation on what this error means is very sparse
+    #[error("opentelemetry error")]
+    Otel(#[from] opentelemetry::trace::TraceError),
+
+    #[error("invalid log filter syntax")]
+    EnvFilter(#[from] tracing_subscriber::filter::ParseError),
+
+    #[error("failed to install global default tracing subscriber")]
+    SetSubscriber(#[from] tracing::subscriber::SetGlobalDefaultError),
+
+    // Upstream's documentation on what this error means is very sparse
+    #[error("tracing_flame error")]
+    TracingFlame(#[from] tracing_flame::Error),
+
+    #[error("failed to load or create the database")]
+    DatabaseError(#[source] crate::utils::error::Error),
+
+    #[error("failed to serve requests")]
+    Serve(#[source] std::io::Error),
+}

src/lib.rs

@@ -2,6 +2,7 @@ pub mod api;
 pub mod clap;
 mod config;
 mod database;
+pub mod error;
 mod service;
 mod utils;
 

src/main.rs

@@ -1,4 +1,4 @@
-use std::{future::Future, io, net::SocketAddr, sync::atomic, time::Duration};
+use std::{future::Future, io, net::SocketAddr, process::ExitCode, sync::atomic, time::Duration};
 
 use axum::{
     extract::{DefaultBodyLimit, FromRequestParts, MatchedPath},
@@ -31,7 +31,7 @@ use tower_http::{
     trace::TraceLayer,
     ServiceBuilderExt as _,
 };
-use tracing::{debug, error, info, warn};
+use tracing::{debug, info, warn};
 use tracing_subscriber::{prelude::*, EnvFilter};
 
 pub use conduit::*; // Re-export everything from the library crate
@@ -44,27 +44,28 @@ use tikv_jemallocator::Jemalloc;
 static GLOBAL: Jemalloc = Jemalloc;
 
 #[tokio::main]
-async fn main() {
+async fn main() -> ExitCode {
+    let Err(e) = try_main().await else {
+        return ExitCode::SUCCESS;
+    };
+
+    eprintln!("error: {}", error::Chain(&e));
+
+    ExitCode::FAILURE
+}
+
+/// Fallible entrypoint
+async fn try_main() -> Result<(), error::CliError> {
+    use error::CliError as Error;
+
     clap::parse();
 
     // Initialize config
-    let raw_config =
-        Figment::new()
-            .merge(
-                Toml::file(Env::var("CONDUIT_CONFIG").expect(
-                    "The CONDUIT_CONFIG env var needs to be set. Example: /etc/conduit.toml",
-                ))
-                .nested(),
-            )
-            .merge(Env::prefixed("CONDUIT_").global());
+    let raw_config = Figment::new()
+        .merge(Toml::file(Env::var("CONDUIT_CONFIG").ok_or(Error::ConfigPathUnset)?).nested())
+        .merge(Env::prefixed("CONDUIT_").global());
 
-    let config = match raw_config.extract::<Config>() {
-        Ok(s) => s,
-        Err(e) => {
-            eprintln!("It looks like your config is invalid. The following error occurred: {e}");
-            std::process::exit(1);
-        }
-    };
+    let config = raw_config.extract::<Config>()?;
 
     config.warn_deprecated();
 
@@ -73,47 +74,31 @@ async fn main() {
         let tracer = opentelemetry_jaeger::new_agent_pipeline()
             .with_auto_split_batch(true)
             .with_service_name("conduit")
-            .install_batch(opentelemetry::runtime::Tokio)
-            .unwrap();
+            .install_batch(opentelemetry::runtime::Tokio)?;
         let telemetry = tracing_opentelemetry::layer().with_tracer(tracer);
 
-        let filter_layer = match EnvFilter::try_new(&config.log) {
-            Ok(s) => s,
-            Err(e) => {
-                eprintln!(
-                    "It looks like your log config is invalid. The following error occurred: {e}"
-                );
-                EnvFilter::try_new("warn").unwrap()
-            }
-        };
+        let filter_layer = EnvFilter::try_new(&config.log)?;
 
         let subscriber = tracing_subscriber::Registry::default()
             .with(filter_layer)
             .with(telemetry);
-        tracing::subscriber::set_global_default(subscriber).unwrap();
+        tracing::subscriber::set_global_default(subscriber)?;
     } else if config.tracing_flame {
         let registry = tracing_subscriber::Registry::default();
-        let (flame_layer, _guard) =
-            tracing_flame::FlameLayer::with_file("./tracing.folded").unwrap();
+        let (flame_layer, _guard) = tracing_flame::FlameLayer::with_file("./tracing.folded")?;
         let flame_layer = flame_layer.with_empty_samples(false);
 
         let filter_layer = EnvFilter::new("trace,h2=off");
 
         let subscriber = registry.with(filter_layer).with(flame_layer);
-        tracing::subscriber::set_global_default(subscriber).unwrap();
+        tracing::subscriber::set_global_default(subscriber)?;
     } else {
         let registry = tracing_subscriber::Registry::default();
         let fmt_layer = tracing_subscriber::fmt::Layer::new();
-        let filter_layer = match EnvFilter::try_new(&config.log) {
-            Ok(s) => s,
-            Err(e) => {
-                eprintln!("It looks like your config is invalid. The following error occured while parsing it: {e}");
-                EnvFilter::try_new("warn").unwrap()
-            }
-        };
+        let filter_layer = EnvFilter::try_new(&config.log)?;
 
         let subscriber = registry.with(filter_layer).with(fmt_layer);
-        tracing::subscriber::set_global_default(subscriber).unwrap();
+        tracing::subscriber::set_global_default(subscriber)?;
     }
 
     // This is needed for opening lots of file descriptors, which tends to
@@ -127,19 +112,19 @@ async fn main() {
     maximize_fd_limit().expect("should be able to increase the soft limit to the hard limit");
 
     info!("Loading database");
-    if let Err(error) = KeyValueDatabase::load_or_create(config).await {
-        error!(?error, "The database couldn't be loaded or created");
-
-        std::process::exit(1);
-    };
+    KeyValueDatabase::load_or_create(config)
+        .await
+        .map_err(Error::DatabaseError)?;
     let config = &services().globals.config;
 
     info!("Starting server");
-    run_server().await.unwrap();
+    run_server().await.map_err(Error::Serve)?;
 
     if config.allow_jaeger {
         opentelemetry::global::shutdown_tracer_provider();
     }
+
+    Ok(())
 }
 
 /// Adds additional headers to prevent any potential XSS attacks via the media repo