[syslog] Add support to logging to syslog

Original patch by Jakub Jirutka for Alpine Linux port.

6 files changed, 80 insertions, 12 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 2b2111c9..b4cf5bd0 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1322,6 +1322,7 @@ dependencies = [
  "sha2",
  "static_init",
  "structopt",
+ "syslog-tracing",
  "timeago",
  "tokio",
  "toml",
@@ -3931,6 +3932,17 @@ dependencies = [
 ]
 
 [[package]]
+name = "syslog-tracing"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "340b1540dcdb6b066bc2966e7974f977ab1a38f21b2be189014ffb0cc2405768"
+dependencies = [
+ "libc",
+ "tracing-core",
+ "tracing-subscriber",
+]
+
+[[package]]
 name = "system-configuration"
 version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
diff --git a/Cargo.nix b/Cargo.nix
index 852e96bf..44cb23b5 100644
--- a/Cargo.nix
+++ b/Cargo.nix
@@ -34,7 +34,7 @@ args@{
   ignoreLockHash,
 }:
 let
-  nixifiedLockHash = "b35dd31aa882ac6fc7105fb99a6681a4777ed269191cb0a8c8db843910748435";
+  nixifiedLockHash = "1d6c837fe8357cbb1b231c1843bde1729c9864f05e5ae251be045450a0b592e3";
   workspaceSrc = if args.workspaceSrc == null then ./. else args.workspaceSrc;
   currentLockHash = builtins.hashFile "sha256" (workspaceSrc + /Cargo.lock);
   lockHashIgnored = if ignoreLockHash
@@ -1889,6 +1889,8 @@ in
       (lib.optional (rootFeatures' ? "garage/default" || rootFeatures' ? "garage/metrics" || rootFeatures' ? "garage/prometheus") "prometheus")
       (lib.optional (rootFeatures' ? "garage/default" || rootFeatures' ? "garage/sled") "sled")
       (lib.optional (rootFeatures' ? "garage/default" || rootFeatures' ? "garage/sqlite") "sqlite")
+      (lib.optional (rootFeatures' ? "garage/syslog") "syslog")
+      (lib.optional (rootFeatures' ? "garage/syslog" || rootFeatures' ? "garage/syslog-tracing") "syslog-tracing")
       (lib.optional (rootFeatures' ? "garage/system-libs") "system-libs")
       (lib.optional (rootFeatures' ? "garage/telemetry-otlp") "telemetry-otlp")
     ];
@@ -1921,6 +1923,7 @@ in
       serde = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".serde."1.0.196" { inherit profileName; }).out;
       serde_bytes = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".serde_bytes."0.11.14" { inherit profileName; }).out;
       structopt = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".structopt."0.3.26" { inherit profileName; }).out;
+      ${ if rootFeatures' ? "garage/syslog" || rootFeatures' ? "garage/syslog-tracing" then "syslog_tracing" else null } = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".syslog-tracing."0.3.0" { inherit profileName; }).out;
       timeago = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".timeago."0.4.2" { inherit profileName; }).out;
       tokio = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".tokio."1.36.0" { inherit profileName; }).out;
       toml = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".toml."0.8.10" { inherit profileName; }).out;
@@ -5612,6 +5615,18 @@ in
     };
   });
   
+  "registry+https://github.com/rust-lang/crates.io-index".syslog-tracing."0.3.0" = overridableMkRustCrate (profileName: rec {
+    name = "syslog-tracing";
+    version = "0.3.0";
+    registry = "registry+https://github.com/rust-lang/crates.io-index";
+    src = fetchCratesIo { inherit name version; sha256 = "340b1540dcdb6b066bc2966e7974f977ab1a38f21b2be189014ffb0cc2405768"; };
+    dependencies = {
+      ${ if rootFeatures' ? "garage/syslog" || rootFeatures' ? "garage/syslog-tracing" then "libc" else null } = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".libc."0.2.153" { inherit profileName; }).out;
+      ${ if rootFeatures' ? "garage/syslog" || rootFeatures' ? "garage/syslog-tracing" then "tracing_core" else null } = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".tracing-core."0.1.32" { inherit profileName; }).out;
+      ${ if rootFeatures' ? "garage/syslog" || rootFeatures' ? "garage/syslog-tracing" then "tracing_subscriber" else null } = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".tracing-subscriber."0.3.18" { inherit profileName; }).out;
+    };
+  });
+  
   "registry+https://github.com/rust-lang/crates.io-index".system-configuration."0.5.1" = overridableMkRustCrate (profileName: rec {
     name = "system-configuration";
     version = "0.5.1";
diff --git a/Cargo.toml b/Cargo.toml
index c6f6f963..d3bbb301 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -72,6 +72,7 @@ kuska-handshake = { version = "0.2.0", features = ["default", "async_std"] }
 clap = { version = "4.1", features = ["derive", "env"] }
 pretty_env_logger = "0.5"
 structopt = { version = "0.3", default-features = false }
+syslog-tracing = "0.3"
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
 
diff --git a/nix/compile.nix b/nix/compile.nix
index b276495d..fdb427f2 100644
--- a/nix/compile.nix
+++ b/nix/compile.nix
@@ -173,6 +173,7 @@ let
       "garage/kubernetes-discovery"
       "garage/metrics"
       "garage/telemetry-otlp"
+      "garage/syslog"
     ] else
       [ ]));
 
diff --git a/src/garage/Cargo.toml b/src/garage/Cargo.toml
index b022049c..52861853 100644
--- a/src/garage/Cargo.toml
+++ b/src/garage/Cargo.toml
@@ -58,6 +58,7 @@ opentelemetry.workspace = true
 opentelemetry-prometheus = { workspace = true, optional = true }
 opentelemetry-otlp = { workspace = true, optional = true }
 prometheus = { workspace = true, optional = true }
+syslog-tracing = { workspace = true, optional = true }
 
 [dev-dependencies]
 aws-config.workspace = true
@@ -97,6 +98,8 @@ kubernetes-discovery = [ "garage_rpc/kubernetes-discovery" ]
 metrics = [ "garage_api/metrics", "opentelemetry-prometheus", "prometheus" ]
 # Exporter for the OpenTelemetry Collector.
 telemetry-otlp = [ "opentelemetry-otlp" ]
+# Logging to syslog
+syslog = [ "syslog-tracing" ]
 
 # NOTE: bundled-libs and system-libs should be treat as mutually exclusive;
 # exactly one of them should be enabled.
diff --git a/src/garage/main.rs b/src/garage/main.rs
index e489fff0..3fe96338 100644
--- a/src/garage/main.rs
+++ b/src/garage/main.rs
@@ -140,17 +140,8 @@ async fn main() {
 	let opt = Opt::from_clap(&Opt::clap().version(version.as_str()).get_matches());
 
 	// Initialize logging as well as other libraries used in Garage
-	if std::env::var("RUST_LOG").is_err() {
-		let default_log = match &opt.cmd {
-			Command::Server => "netapp=info,garage=info",
-			_ => "netapp=warn,garage=warn",
-		};
-		std::env::set_var("RUST_LOG", default_log)
-	}
-	tracing_subscriber::fmt()
-		.with_writer(std::io::stderr)
-		.with_env_filter(tracing_subscriber::filter::EnvFilter::from_default_env())
-		.init();
+	init_logging(&opt);
+
 	sodiumoxide::init().expect("Unable to init sodiumoxide");
 
 	let res = match opt.cmd {
@@ -173,6 +164,51 @@ async fn main() {
 	}
 }
 
+fn init_logging(opt: &Opt) {
+	if std::env::var("RUST_LOG").is_err() {
+		let default_log = match &opt.cmd {
+			Command::Server => "netapp=info,garage=info",
+			_ => "netapp=warn,garage=warn",
+		};
+		std::env::set_var("RUST_LOG", default_log)
+	}
+
+	let env_filter = tracing_subscriber::filter::EnvFilter::from_default_env();
+
+	#[cfg(feature = "syslog")]
+	if std::env::var("GARAGE_LOG_TO_SYSLOG")
+		.map(|x| x == "1" || x == "true")
+		.unwrap_or(false)
+	{
+		use std::ffi::CStr;
+		use syslog_tracing::{Facility, Options, Syslog};
+
+		let syslog = Syslog::new(
+			CStr::from_bytes_with_nul(b"garage\0").unwrap(),
+			Options::LOG_PID | Options::LOG_PERROR,
+			Facility::Daemon,
+		)
+		.expect("Unable to init syslog");
+
+		tracing_subscriber::fmt()
+			.with_writer(syslog)
+			.with_env_filter(env_filter)
+			.with_ansi(false) // disable ANSI escape sequences (colours)
+			.with_file(false)
+			.with_level(false)
+			.without_time()
+			.compact()
+			.init();
+
+		return;
+	}
+
+	tracing_subscriber::fmt()
+		.with_writer(std::io::stderr)
+		.with_env_filter(env_filter)
+		.init();
+}
+
 async fn cli_command(opt: Opt) -> Result<(), Error> {
 	let config = if (opt.secrets.rpc_secret.is_none() && opt.secrets.rpc_secret_file.is_none())
 		|| opt.rpc_host.is_none()