Create Prometheus labels for all files found at startup

docker/docker-compose.yml

@@ -44,7 +44,8 @@ services:
       - logs:/logs
     environment:
       HTTP_HOST: "0.0.0.0"
-      LOG_FILE_PATTERN: "/logs/*.access.log"
+      ACCESS_LOG_FILE_PATTERN: "/logs/*.access.log"
+      ERROR_LOG_FILE_PATTERN: "/logs/*.error.log"
     restart: "always"
 
 volumes: 

src/apache_metrics.rs

@@ -2,22 +2,26 @@ use prometheus_client::metrics::counter::Counter;
 use prometheus_client::metrics::family::Family;
 use prometheus_client::registry::Registry;
 
+type SingleLabel = (&'static str, String);
+
 #[derive(Clone)]
 pub struct ApacheMetrics {
-	pub requests_total: Family<(&'static str, String), Counter>
+	pub requests_total: Family<SingleLabel, Counter>,
+	pub errors_total: Family<SingleLabel, Counter>
 }
 
 impl ApacheMetrics {
 	pub fn new() -> (Registry, ApacheMetrics) {
 		let mut registry = <Registry>::default();
 		
-		let requests_total = Family::<(&'static str, String), Counter>::default();
-		registry.register("apache_requests", "Number of received requests", Box::new(requests_total.clone()));
-		
 		let metrics = ApacheMetrics {
-			requests_total
+			requests_total: Family::<SingleLabel, Counter>::default(),
+			errors_total: Family::<SingleLabel, Counter>::default()
 		};
 		
+		registry.register("apache_requests", "Number of received requests", Box::new(metrics.requests_total.clone()));
+		registry.register("apache_errors", "Number of logged errors", Box::new(metrics.errors_total.clone()));
+		
 		return (registry, metrics);
 	}
 }

src/log_file_pattern.rs

@@ -6,24 +6,22 @@ use std::path::{Path, PathBuf};
 
 use path_slash::PathExt;
 
-/// Environment variable that determines the path and file name pattern of log files.
+/// Reads and parses an environment variable that determines the path and file name pattern of log files.
 ///
 /// Supports 3 pattern types:
 ///
 /// 1. A simple path to a file.
 /// 2. A path with a wildcard anywhere in the file name.
 /// 3. A path with a standalone wildcard component (i.e. no prefix or suffix in the folder name).
-pub const LOG_FILE_PATTERN: &'static str = "LOG_FILE_PATTERN";
-
-pub fn parse_log_file_pattern_from_env() -> Result<LogFilePattern, String> {
-	return match env::var(LOG_FILE_PATTERN) {
+pub fn parse_log_file_pattern_from_env(variable_name: &str) -> Result<LogFilePattern, String> {
+	return match env::var(variable_name) {
 		Ok(str) => {
-			let pattern_str = Path::new(&str).to_slash().ok_or(format!("Environment variable {} contains an invalid path.", LOG_FILE_PATTERN))?;
+			let pattern_str = Path::new(&str).to_slash().ok_or(format!("Environment variable {} contains an invalid path.", variable_name))?;
 			parse_log_file_pattern_from_str(&pattern_str)
 		}
 		Err(err) => match err {
-			VarError::NotPresent => Err(format!("Environment variable {} must be set.", LOG_FILE_PATTERN)),
-			VarError::NotUnicode(_) => Err(format!("Environment variable {} contains invalid characters.", LOG_FILE_PATTERN))
+			VarError::NotPresent => Err(format!("Environment variable {} must be set.", variable_name)),
+			VarError::NotUnicode(_) => Err(format!("Environment variable {} contains invalid characters.", variable_name))
 		}
 	};
 }

src/log_watcher.rs

@@ -3,47 +3,110 @@ use std::io;
 use std::io::{Error, ErrorKind};
 use std::path::PathBuf;
 
-use linemux::MuxedLines;
+use linemux::{Line, MuxedLines};
 use tokio::sync::mpsc::UnboundedSender;
 
 use crate::ApacheMetrics;
 use crate::log_file_pattern::LogFilePath;
 
-pub async fn read_logs_task(log_files: Vec<LogFilePath>, metrics: ApacheMetrics, shutdown_send: UnboundedSender<()>) {
-	if let Err(error) = read_logs(log_files, metrics).await {
+#[derive(Copy, Clone, PartialEq)]
+enum LogFileKind {
+	Access,
+	Error,
+}
+
+struct LogFileInfo<'a> {
+	pub kind: LogFileKind,
+	pub label: &'a String,
+}
+
+impl<'a> LogFileInfo<'a> {
+	fn get_label_set(&self) -> (&'static str, String) {
+		return ("file", self.label.clone());
+	}
+}
+
+pub async fn watch_logs_task(access_log_files: Vec<LogFilePath>, error_log_files: Vec<LogFilePath>, metrics: ApacheMetrics, shutdown_send: UnboundedSender<()>) {
+	if let Err(error) = watch_logs(access_log_files, error_log_files, metrics).await {
 		println!("[LogWatcher] Error reading logs: {}", error);
 		shutdown_send.send(()).unwrap();
 	}
 }
 
-async fn read_logs(log_files: Vec<LogFilePath>, metrics: ApacheMetrics) -> io::Result<()> {
-	let mut file_reader = MuxedLines::new()?;
-	let mut label_lookup: HashMap<PathBuf, &String> = HashMap::new();
-	
-	for log_file in &log_files {
-		let lookup_key = file_reader.add_file(&log_file.path).await?;
-		label_lookup.insert(lookup_key, &log_file.label);
+struct LogWatcher<'a> {
+	reader: MuxedLines,
+	files: HashMap<PathBuf, LogFileInfo<'a>>,
+}
+
+impl<'a> LogWatcher<'a> {
+	fn new() -> io::Result<LogWatcher<'a>> {
+		return Ok(LogWatcher {
+			reader: MuxedLines::new()?,
+			files: HashMap::new(),
+		});
 	}
 	
-	if log_files.is_empty() {
-		println!("[LogWatcher] No log files provided.");
-		return Err(Error::from(ErrorKind::Unsupported));
+	fn count_files_of_kind(&self, kind: LogFileKind) -> usize {
+		return self.files.values().filter(|info| info.kind == kind).count();
 	}
 	
-	println!("[LogWatcher] Watching {} log file(s).", log_files.len());
+	async fn add_file(&mut self, log_file: &'a LogFilePath, kind: LogFileKind) -> io::Result<()> {
+		let lookup_key = self.reader.add_file(&log_file.path).await?;
+		self.files.insert(lookup_key, LogFileInfo { kind, label: &log_file.label });
+		Ok(())
+	}
 	
-	loop {
-		let event_result = file_reader.next_line().await?;
-		if let Some(event) = event_result {
-			match label_lookup.get(event.source()) {
-				Some(&label) => {
-					println!("[LogWatcher] Received line from \"{}\": {}", label, event.line());
-					metrics.requests_total.get_or_create(&("file", label.clone())).inc();
-				}
-				None => {
-					println!("[LogWatcher] Received line from unknown file: {}", event.source().display());
-				}
+	async fn start_watching(&mut self, metrics: &ApacheMetrics) -> io::Result<()> {
+		if self.files.is_empty() {
+			println!("[LogWatcher] No log files provided.");
+			return Err(Error::from(ErrorKind::Unsupported));
+		}
+		
+		println!("[LogWatcher] Watching {} access log file(s) and {} error log file(s).", self.count_files_of_kind(LogFileKind::Access), self.count_files_of_kind(LogFileKind::Error));
+		
+		for metadata in self.files.values() {
+			let label_set = metadata.get_label_set();
+			let _ = metrics.requests_total.get_or_create(&label_set);
+			let _ = metrics.errors_total.get_or_create(&label_set);
+		}
+		
+		loop {
+			if let Some(event) = self.reader.next_line().await? {
+				self.handle_line(event, metrics);
+			}
+		}
+	}
+	
+	fn handle_line(&mut self, event: Line, metrics: &ApacheMetrics) {
+		match self.files.get(event.source()) {
+			Some(metadata) => {
+				let label = metadata.label;
+				let (kind, family) = match metadata.kind {
+					LogFileKind::Access => ("access log", &metrics.requests_total),
+					LogFileKind::Error => ("error log", &metrics.errors_total),
+				};
+				
+				println!("[LogWatcher] Received {} line from \"{}\": {}", kind, label, event.line());
+				family.get_or_create(&metadata.get_label_set()).inc();
+			}
+			None => {
+				println!("[LogWatcher] Received line from unknown file: {}", event.source().display());
 			}
 		}
 	}
 }
+
+async fn watch_logs(access_log_files: Vec<LogFilePath>, error_log_files: Vec<LogFilePath>, metrics: ApacheMetrics) -> io::Result<()> {
+	let mut watcher = LogWatcher::new()?;
+	
+	for log_file in &access_log_files {
+		watcher.add_file(log_file, LogFileKind::Access).await?;
+	}
+	
+	for log_file in &error_log_files {
+		watcher.add_file(log_file, LogFileKind::Error).await?;
+	}
+	
+	watcher.start_watching(&metrics).await?;
+	Ok(())
+}

src/main.rs

@@ -1,12 +1,13 @@
 use std::env;
+use std::process::ExitCode;
 use std::sync::Mutex;
 
 use tokio::signal;
 use tokio::sync::mpsc;
 
 use crate::apache_metrics::ApacheMetrics;
-use crate::log_file_pattern::parse_log_file_pattern_from_env;
-use crate::log_watcher::read_logs_task;
+use crate::log_file_pattern::{LogFilePath, parse_log_file_pattern_from_env};
+use crate::log_watcher::watch_logs_task;
 use crate::web_server::{create_web_server, run_web_server};
 
 mod log_file_pattern;
@@ -14,41 +15,58 @@ mod log_watcher;
 mod apache_metrics;
 mod web_server;
 
-#[tokio::main(flavor = "current_thread")]
-async fn main() {
-	let host = env::var("HTTP_HOST").unwrap_or(String::from("127.0.0.1"));
-	
-	println!("Initializing exporter...");
-	
-	let log_file_pattern = match parse_log_file_pattern_from_env() {
+const ACCESS_LOG_FILE_PATTERN: &'static str = "ACCESS_LOG_FILE_PATTERN";
+const ERROR_LOG_FILE_PATTERN: &'static str = "ERROR_LOG_FILE_PATTERN";
+
+fn find_log_files(environment_variable_name: &str, log_kind: &str) -> Option<Vec<LogFilePath>> {
+	let log_file_pattern = match parse_log_file_pattern_from_env(environment_variable_name) {
 		Ok(pattern) => pattern,
 		Err(error) => {
 			println!("Error: {}", error);
-			return;
+			return None;
 		}
 	};
 	
 	let log_files = match log_file_pattern.search() {
 		Ok(files) => files,
 		Err(error) => {
-			println!("Error searching log files: {}", error);
-			return;
+			println!("Error searching {} files: {}", log_kind, error);
+			return None;
 		}
 	};
 	
 	if log_files.is_empty() {
-		println!("Found no matching log files.");
-		return;
+		println!("Found no matching {} files.", log_kind);
+		return None;
 	}
 	
 	for log_file in &log_files {
-		println!("Found log file: {} (label \"{}\")", log_file.path.display(), log_file.label);
+		println!("Found {} file: {} (label \"{}\")", log_kind, log_file.path.display(), log_file.label);
 	}
 	
+	return Some(log_files);
+}
+
+#[tokio::main(flavor = "current_thread")]
+async fn main() -> ExitCode {
+	let host = env::var("HTTP_HOST").unwrap_or(String::from("127.0.0.1"));
+	
+	println!("Initializing exporter...");
+	
+	let access_log_files = match find_log_files(ACCESS_LOG_FILE_PATTERN, "access log") {
+		Some(files) => files,
+		None => return ExitCode::FAILURE,
+	};
+	
+	let error_log_files = match find_log_files(ERROR_LOG_FILE_PATTERN, "error log") {
+		Some(files) => files,
+		None => return ExitCode::FAILURE,
+	};
+	
 	let (metrics_registry, metrics) = ApacheMetrics::new();
 	let (shutdown_send, mut shutdown_recv) = mpsc::unbounded_channel();
 	
-	tokio::spawn(read_logs_task(log_files, metrics.clone(), shutdown_send.clone()));
+	tokio::spawn(watch_logs_task(access_log_files, error_log_files, metrics.clone(), shutdown_send.clone()));
 	tokio::spawn(run_web_server(create_web_server(host.as_str(), 9240, Mutex::new(metrics_registry))));
 	
 	drop(shutdown_send);
@@ -62,4 +80,6 @@ async fn main() {
 			println!("Shutting down...");
 		}
 	}
+	
+	ExitCode::SUCCESS
 }