Implement proper logging instead of using println!() everywhere

Cargo.toml

@@ -12,7 +12,9 @@ license = "AGPL-3.0-only"
 [dependencies]
 argon2 = { version = "0.5", features = ["std"] }
 clap = { version = "4.5", features = ["derive"] }
+env_logger = "0.11"
 error-chain = "0.12"
+log = "0.4"
 serde = "1.0"
 serde_derive = "1.0"
 tokio = { version = "1", features = ["full"] }
@@ -24,6 +26,8 @@ unsafe_code = "forbid"
 
 [lints.clippy]
 enum_glob_use = "warn"
-pedantic = "warn"
 nursery = "warn"
+pedantic = "warn"
+print_stdout = "warn"
 unwrap_used = "warn"
+use_debug = "warn"

README.md

@@ -72,7 +72,6 @@ If you would like to see any of the following TODO items implemented, please fil
 - Test on platforms other than `x86_64-linux`
 - Use systemd socket activation for lower resource usage
 - Support HTTP basic auth
-- Implement proper logging with different log levels to reduce log spam
 - Improve documentation
 - Add some simpler tests in Rust in addition to the NixOS test
 - Make use of the `ipv6lanprefix` sent by FRITZ!Boxes

src/logging.rs

@@ -0,0 +1,32 @@
+// SPDX-FileCopyrightText: 2024 Luflosi <[email protected]>
+// SPDX-License-Identifier: AGPL-3.0-only
+
+use env_logger::{Builder, Env};
+use std::io::Write;
+
+pub fn setup() {
+	let env = Env::default().filter_or("RUST_LOG", "dyndnsd=info");
+
+	match std::env::var("RUST_LOG_STYLE") {
+		Ok(s) if s == "SYSTEMD" => Builder::from_env(env)
+			.format(|buf, record| {
+				for line in record.args().to_string().lines() {
+					writeln!(
+						buf,
+						"<{}>{}: {}",
+						match record.level() {
+							log::Level::Error => 3,
+							log::Level::Warn => 4,
+							log::Level::Info => 6,
+							log::Level::Debug | log::Level::Trace => 7,
+						},
+						record.target(),
+						line
+					)?;
+				}
+				Ok(())
+			})
+			.init(),
+		_ => env_logger::init_from_env(env),
+	}
+}

src/main.rs

@@ -1,17 +1,19 @@
 // SPDX-FileCopyrightText: 2024 Luflosi <[email protected]>
 // SPDX-License-Identifier: AGPL-3.0-only
 
+mod config;
+mod logging;
+mod process;
+
 #[macro_use]
 extern crate error_chain;
 
 use crate::config::Config;
 use crate::process::{update, QueryParameters};
 use clap::Parser;
+use log::{error, info};
 use warp::Filter;
 
-mod config;
-mod process;
-
 #[derive(Parser, Debug)]
 #[command(version)]
 struct Args {
@@ -22,16 +24,18 @@ struct Args {
 
 #[tokio::main]
 async fn main() {
+	logging::setup();
+
 	let args = Args::parse();
 
 	let config = match Config::read(&args.config) {
 		Ok(v) => v,
 		Err(e) => {
-			eprintln!("ERROR: {e}");
+			error!("ERROR: {e}");
 
 			/////// look at the chain of errors... ///////
 			for e in e.iter().skip(1) {
-				eprintln!("caused by: {e}");
+				error!("caused by: {e}");
 			}
 
 			std::process::exit(1);
@@ -45,6 +49,6 @@ async fn main() {
 		.and(warp::query::<QueryParameters>())
 		.map(move |q: QueryParameters| update(&config, &q));
 
-	println!("Listening on {listen}");
+	info!("Listening on {listen}");
 	warp::serve(update).run(listen).await;
 }

src/process.rs

@@ -3,6 +3,7 @@
 
 use crate::config::{Config, User};
 use argon2::{password_hash::PasswordVerifier, Argon2};
+use log::{debug, error, info, trace, warn};
 use serde_derive::Deserialize;
 use std::io::Write;
 use std::net::{Ipv4Addr, Ipv6Addr};
@@ -11,7 +12,7 @@ use warp::{http::StatusCode, Reply};
 
 #[derive(Deserialize)]
 pub struct QueryParameters {
-	domain: Option<String>,
+	domain: Option<String>, // Ignored, we use the username to determine the list of domains to be updated
 	user: String,
 	pass: String,
 	ipv4: Option<Ipv4Addr>,
@@ -36,7 +37,7 @@ fn build_command_string(config: &Config, user: &User, q: &QueryParameters) -> St
 	command.push_str(config.update_program.initial_stdin.as_str());
 	let domains = &user.domains;
 	for (domain, props) in domains {
-		println!("{domain:?} {props:?}");
+		trace!("Domain: {domain:?} {props:?}");
 		let ttl = &props.ttl.to_string();
 		if let Some(ipv4) = q.ipv4 {
 			let ipv4 = &ipv4.to_string();
@@ -53,7 +54,7 @@ fn build_command_string(config: &Config, user: &User, q: &QueryParameters) -> St
 		}
 		if let Some(prefix) = q.ipv6 {
 			if props.ipv6prefixlen == 0 {
-				println!("IPv6 prefix length for domain {domain} is zero, ignoring update to IPv6 address");
+				warn!("IPv6 prefix length for domain {domain} is zero, ignoring update to IPv6 address");
 			} else {
 				let assembled_addr =
 					splice_ipv6_addrs(props.ipv6prefixlen, prefix, props.ipv6suffix);
@@ -73,12 +74,13 @@ fn build_command_string(config: &Config, user: &User, q: &QueryParameters) -> St
 		command.push_str(config.update_program.stdin_per_zone_update.as_str());
 	}
 	command.push_str(config.update_program.final_stdin.as_str());
-	println!("{command}");
+	debug!("Commands for update program:\n{command}");
 	command
 }
 
 pub fn update(config: &Config, q: &QueryParameters) -> Result<impl Reply, impl Reply> {
-	println!("domain: {:?}, user: {:?}, pass: <redacted>, ipv4: {:?}, ipv6: {:?}, dualstack: {:?}, ipv6lanprefix: {:?}", &q.domain, &q.user, &q.ipv4, &q.ipv6, &q.dualstack, &q.ipv6lanprefix);
+	info!("Incoming request from user `{}`", &q.user);
+	debug!("domain: {:?}, user: {:?}, pass: <redacted>, ipv4: {:?}, ipv6: {:?}, dualstack: {:?}, ipv6lanprefix: {:?}", &q.domain, &q.user, &q.ipv4, &q.ipv6, &q.dualstack, &q.ipv6lanprefix);
 
 	let Some(user) = config.users.get(&q.user) else {
 		eprintln!("User {} does not exist.", q.user);
@@ -96,7 +98,7 @@ pub fn update(config: &Config, q: &QueryParameters) -> Result<impl Reply, impl R
 		));
 	};
 
-	println!("Authentication successful");
+	info!("Authentication successful");
 
 	let command = build_command_string(config, user, q);
 
@@ -137,20 +139,20 @@ pub fn update(config: &Config, q: &QueryParameters) -> Result<impl Reply, impl R
 
 	let status = output.status;
 	if !status.success() {
-		println!("The update program failed with {status}");
+		error!("The update program failed with {status}");
 		let stdout = String::from_utf8_lossy(&output.stdout);
 		if !stdout.is_empty() {
-			println!("and stdout: `{stdout}`");
+			error!("and stdout: `{stdout}`");
 		}
 		let stderr = String::from_utf8_lossy(&output.stderr);
 		if !stderr.is_empty() {
-			println!("and stderr: `{stderr}`");
+			error!("and stderr: `{stderr}`");
 		}
 		return Err(warp::reply::with_status(
 			"ERROR".to_string(),
 			StatusCode::INTERNAL_SERVER_ERROR,
 		));
 	}
-	println!("Success");
+	info!("Successfully processed update request");
 	Ok(warp::reply::with_status("ok".to_string(), StatusCode::OK))
 }

systemd/dyndnsd.service

@@ -45,5 +45,10 @@ SystemCallFilter=~@privileged
 Type=simple
 UMask=0077
 
+Environment="RUST_LOG_STYLE=SYSTEMD"
+
+# Uncomment for maximum verbosity
+#Environment="RUST_LOG=dyndnsd=trace"
+
 [Install]
 WantedBy=multi-user.target