Refactor cli, tracing, server out of main.rs

src/app.rs

@@ -86,7 +86,14 @@ fn router() -> Router {
         .nest("/v1", v1())
 }
 
-/// Returns a [tower_service::Service] for the Active Storage server API
+/// S3 Active Storage Server Service type alias
+///
+/// This type implements [tower_service::Service].
+// FIXME: The Service type should be some form of tower_service::Service, but couldn't find the
+// necessary trait bounds.
+pub type Service = tower_http::normalize_path::NormalizePath<Router>;
+
+/// Returns a [crate::app::Service] for the Active Storage server API
 ///
 /// The service is populated with all routes as well as the following middleware:
 ///
@@ -95,10 +102,7 @@ fn router() -> Router {
 ///   headers
 /// * a [tower_http::normalize_path::NormalizePathLayer] for trimming trailing slashes from
 ///   requests
-pub fn service() -> tower_http::normalize_path::NormalizePath<Router> {
-    // FIXME: The return type should be some form of tower_service::Service, but couldn't find the
-    // necessary trait bounds.
-
+pub fn service() -> Service {
     // Note that any middleware that should affect routing must wrap the router.
     // See
     // https://docs.rs/axum/0.6.18/axum/middleware/index.html#rewriting-request-uri-in-middleware.

src/cli.rs

@@ -0,0 +1,39 @@
+//! Command Line Interface (CLI) arguments.
+
+use clap::Parser;
+
+/// S3 Active Storage Proxy command line interface
+#[derive(Debug, Parser)]
+pub struct CommandLineArgs {
+    /// The IP address on which the proxy should listen
+    #[arg(long, default_value = "0.0.0.0", env = "S3_ACTIVE_STORAGE_HOST")]
+    pub host: String,
+    /// The port to which the proxy should bind
+    #[arg(long, default_value_t = 8080, env = "S3_ACTIVE_STORAGE_PORT")]
+    pub port: u16,
+    /// Flag indicating whether HTTPS should be used
+    #[arg(long, default_value_t = false, env = "S3_ACTIVE_STORAGE_HTTPS")]
+    pub https: bool,
+    /// Path to the certificate file to be used for HTTPS encryption
+    #[arg(
+        long,
+        default_value = "~/.config/s3-active-storage/certs/cert.pem",
+        env = "S3_ACTIVE_STORAGE_CERT_FILE"
+    )]
+    pub cert_file: String,
+    /// Path to the key file to be used for HTTPS encryption
+    #[arg(
+        long,
+        default_value = "~/.config/s3-active-storage/certs/key.pem",
+        env = "S3_ACTIVE_STORAGE_KEY_FILE"
+    )]
+    pub key_file: String,
+    /// Maximum time in seconds to wait for operations to complete upon receiving `ctrl+c` signal.
+    #[arg(long, default_value_t = 60, env = "S3_ACTIVE_STORAGE_SHUTDOWN_TIMEOUT")]
+    pub graceful_shutdown_timeout: u64,
+}
+
+/// Returns parsed command line arguments.
+pub fn parse() -> CommandLineArgs {
+    CommandLineArgs::parse()
+}

src/main.rs

@@ -22,159 +22,23 @@
 //! * [ndarray] provides [NumPy](https://numpy.orgq)-like n-dimensional arrays used in numerical
 //!   computation.
 
-use std::{net::SocketAddr, process::exit, str::FromStr, time::Duration};
-
-use axum::ServiceExt;
-use axum_server::{tls_rustls::RustlsConfig, Handle};
-use clap::Parser;
-use expanduser::expanduser;
-use tokio::signal;
-use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt};
-
 mod app;
 mod array;
+mod cli;
 mod error;
 mod models;
 mod operation;
 mod operations;
 mod s3_client;
+mod server;
+mod tracing;
 mod validated_json;
 
-/// S3 Active Storage Proxy command line interface
-#[derive(Debug, Parser)]
-struct CommandLineArgs {
-    /// The IP address on which the proxy should listen
-    #[arg(long, default_value = "0.0.0.0", env = "S3_ACTIVE_STORAGE_HOST")]
-    host: String,
-    /// The port to which the proxy should bind
-    #[arg(long, default_value_t = 8080, env = "S3_ACTIVE_STORAGE_PORT")]
-    port: u16,
-    /// Flag indicating whether HTTPS should be used
-    #[arg(long, default_value_t = false, env = "S3_ACTIVE_STORAGE_HTTPS")]
-    https: bool,
-    /// Path to the certificate file to be used for HTTPS encryption
-    #[arg(
-        long,
-        default_value = "~/.config/s3-active-storage/certs/cert.pem",
-        env = "S3_ACTIVE_STORAGE_CERT_FILE"
-    )]
-    cert_file: String,
-    /// Path to the key file to be used for HTTPS encryption
-    #[arg(
-        long,
-        default_value = "~/.config/s3-active-storage/certs/key.pem",
-        env = "S3_ACTIVE_STORAGE_KEY_FILE"
-    )]
-    key_file: String,
-    /// Maximum time in seconds to wait for operations to complete upon receiving `ctrl+c` signal.
-    #[arg(long, default_value_t = 60, env = "S3_ACTIVE_STORAGE_SHUTDOWN_TIMEOUT")]
-    graceful_shutdown_timeout: u64,
-}
-
 /// Application entry point
 #[tokio::main]
 async fn main() {
-    let args = CommandLineArgs::parse();
-
-    init_tracing();
-
+    let args = cli::parse();
+    tracing::init_tracing();
     let service = app::service();
-    let addr = SocketAddr::from_str(&format!("{}:{}", args.host, args.port))
-        .expect("invalid host name, IP address or port number");
-
-    // Catch ctrl+c and try to shutdown gracefully
-    let handle = Handle::new();
-    tokio::spawn(shutdown_signal(
-        handle.clone(),
-        args.graceful_shutdown_timeout,
-    ));
-
-    if args.https {
-        // Expand files
-        let abs_cert_file = expanduser(args.cert_file)
-            .expect("Failed to expand ~ to user name. Please provide an absolute path instead.")
-            .canonicalize()
-            .expect("failed to determine absolute path to TLS cerficate file");
-        let abs_key_file = expanduser(args.key_file)
-            .expect("Failed to expand ~ to user name. Please provide an absolute path instead.")
-            .canonicalize()
-            .expect("failed to determine absolute path to TLS key file");
-        // Check files exist
-        if !abs_cert_file.exists() {
-            println!(
-                "TLS certificate file expected at '{}' but not found.",
-                abs_cert_file.display()
-            );
-            exit(1)
-        }
-        if !abs_key_file.exists() {
-            println!(
-                "TLS key file expected at '{}' but not found.",
-                abs_key_file.display()
-            );
-            exit(1)
-        }
-        // Set up TLS config
-        let tls_config = RustlsConfig::from_pem_file(abs_cert_file, abs_key_file)
-            .await
-            .expect("Failed to load TLS certificate files");
-        // run HTTPS server with hyper
-        axum_server::bind_rustls(addr, tls_config)
-            .handle(handle)
-            .serve(service.into_make_service())
-            .await
-            .unwrap();
-    } else {
-        // run HTTP server with hyper
-        axum_server::bind(addr)
-            .handle(handle)
-            .serve(service.into_make_service())
-            .await
-            .unwrap();
-    }
-}
-
-/// Initlialise tracing (logging)
-///
-/// Applies a filter based on the `RUST_LOG` environment variable, falling back to enable debug
-/// logging for this crate and tower_http if not set.
-fn init_tracing() {
-    tracing_subscriber::registry()
-        .with(
-            tracing_subscriber::EnvFilter::try_from_default_env()
-                .unwrap_or_else(|_| "s3_active_storage=debug,tower_http=debug".into()),
-        )
-        .with(tracing_subscriber::fmt::layer())
-        .init();
-}
-
-/// Graceful shutdown handler
-///
-/// Installs signal handlers to catch Ctrl-C or SIGTERM and trigger a graceful shutdown.
-async fn shutdown_signal(handle: Handle, timeout: u64) {
-    let ctrl_c = async {
-        signal::ctrl_c()
-            .await
-            .expect("failed to install Ctrl+C handler");
-    };
-
-    #[cfg(unix)]
-    let terminate = async {
-        signal::unix::signal(signal::unix::SignalKind::terminate())
-            .expect("failed to install signal handler")
-            .recv()
-            .await;
-    };
-
-    #[cfg(not(unix))]
-    let terminate = std::future::pending::<()>();
-
-    tokio::select! {
-        _ = ctrl_c => {},
-        _ = terminate => {},
-    }
-
-    println!("signal received, starting graceful shutdown");
-    // Force shutdown if graceful shutdown takes longer than 10s
-    handle.graceful_shutdown(Some(Duration::from_secs(timeout)));
+    server::serve(&args, service).await;
 }

src/server.rs

@@ -0,0 +1,103 @@
+//! Web server
+
+use crate::cli;
+
+use std::{net::SocketAddr, process::exit, str::FromStr, time::Duration};
+
+use axum::ServiceExt;
+use axum_server::{tls_rustls::RustlsConfig, Handle};
+use expanduser::expanduser;
+use tokio::signal;
+
+/// Serve the S3 Active Storage service
+///
+/// # Arguments
+///
+/// * `args`: Command line arguments
+/// * `service`: The [crate::app::Service] to serve
+pub async fn serve(args: &cli::CommandLineArgs, service: crate::app::Service) {
+    let addr = SocketAddr::from_str(&format!("{}:{}", args.host, args.port))
+        .expect("invalid host name, IP address or port number");
+
+    // Catch ctrl+c and try to shutdown gracefully
+    let handle = Handle::new();
+    tokio::spawn(shutdown_signal(
+        handle.clone(),
+        args.graceful_shutdown_timeout,
+    ));
+
+    if args.https {
+        // Expand files
+        let abs_cert_file = expanduser(&args.cert_file)
+            .expect("Failed to expand ~ to user name. Please provide an absolute path instead.")
+            .canonicalize()
+            .expect("failed to determine absolute path to TLS cerficate file");
+        let abs_key_file = expanduser(&args.key_file)
+            .expect("Failed to expand ~ to user name. Please provide an absolute path instead.")
+            .canonicalize()
+            .expect("failed to determine absolute path to TLS key file");
+        // Check files exist
+        if !abs_cert_file.exists() {
+            println!(
+                "TLS certificate file expected at '{}' but not found.",
+                abs_cert_file.display()
+            );
+            exit(1)
+        }
+        if !abs_key_file.exists() {
+            println!(
+                "TLS key file expected at '{}' but not found.",
+                abs_key_file.display()
+            );
+            exit(1)
+        }
+        // Set up TLS config
+        let tls_config = RustlsConfig::from_pem_file(abs_cert_file, abs_key_file)
+            .await
+            .expect("Failed to load TLS certificate files");
+        // run HTTPS server with hyper
+        axum_server::bind_rustls(addr, tls_config)
+            .handle(handle)
+            .serve(service.into_make_service())
+            .await
+            .unwrap();
+    } else {
+        // run HTTP server with hyper
+        axum_server::bind(addr)
+            .handle(handle)
+            .serve(service.into_make_service())
+            .await
+            .unwrap();
+    }
+}
+
+/// Graceful shutdown handler
+///
+/// Installs signal handlers to catch Ctrl-C or SIGTERM and trigger a graceful shutdown.
+async fn shutdown_signal(handle: Handle, timeout: u64) {
+    let ctrl_c = async {
+        signal::ctrl_c()
+            .await
+            .expect("failed to install Ctrl+C handler");
+    };
+
+    #[cfg(unix)]
+    let terminate = async {
+        signal::unix::signal(signal::unix::SignalKind::terminate())
+            .expect("failed to install signal handler")
+            .recv()
+            .await;
+    };
+
+    #[cfg(not(unix))]
+    let terminate = std::future::pending::<()>();
+
+    tokio::select! {
+        _ = ctrl_c => {},
+        _ = terminate => {},
+    }
+
+    println!("signal received, starting graceful shutdown");
+    // Force shutdown if graceful shutdown takes longer than 10s
+    handle.graceful_shutdown(Some(Duration::from_secs(timeout)));
+}

src/tracing.rs

@@ -0,0 +1,17 @@
+//! Tracing (logging)
+
+use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt};
+
+/// Initlialise tracing (logging)
+///
+/// Applies a filter based on the `RUST_LOG` environment variable, falling back to enable debug
+/// logging for this crate and tower_http if not set.
+pub fn init_tracing() {
+    tracing_subscriber::registry()
+        .with(
+            tracing_subscriber::EnvFilter::try_from_default_env()
+                .unwrap_or_else(|_| "s3_active_storage=debug,tower_http=debug".into()),
+        )
+        .with(tracing_subscriber::fmt::layer())
+        .init();
+}