Add basic support for metrics

1 files changed, 62 insertions, 8 deletions

diff --git a/src/proxy_config.rs b/src/proxy_config.rs
index e45cc7b..24ade8b 100644
--- a/src/proxy_config.rs
+++ b/src/proxy_config.rs
@@ -4,6 +4,7 @@ use std::sync::{atomic, Arc};
 use std::{cmp, time::Duration};
 
 use anyhow::Result;
+use opentelemetry::{metrics, KeyValue};
 
 use futures::future::BoxFuture;
 use futures::stream::{FuturesUnordered, StreamExt};
@@ -38,6 +39,15 @@ impl HostDescription {
 	}
 }
 
+impl std::fmt::Display for HostDescription {
+	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+		match self {
+			HostDescription::Hostname(h) => write!(f, "{}", h),
+			HostDescription::Pattern(p) => write!(f, "Pattern('{}')", p.as_str()),
+		}
+	}
+}
+
 #[derive(Debug)]
 pub struct ProxyEntry {
 	/// Publicly exposed TLS hostnames for matching this rule
@@ -47,6 +57,8 @@ pub struct ProxyEntry {
 	/// Priority with which this rule is considered (highest first)
 	pub priority: u32,
 
+	/// Consul service name
+	pub service_name: String,
 	/// Node address (ip+port) to handle requests that match this entry
 	pub target_addr: SocketAddr,
 	/// Is the target serving HTTPS instead of HTTP?
@@ -75,14 +87,11 @@ impl std::fmt::Display for ProxyEntry {
 			write!(f, "https://")?;
 		}
 		write!(f, "{} ", self.target_addr)?;
-		match &self.host {
-			HostDescription::Hostname(h) => write!(f, "{}", h)?,
-			HostDescription::Pattern(p) => write!(f, "Pattern('{}')", p.as_str())?,
-		}
 		write!(
 			f,
-			"{} {}",
-			self.path_prefix.as_ref().unwrap_or(&String::new()),
+			"{}{} {}",
+			self.host,
+			self.path_prefix.as_deref().unwrap_or_default(),
 			self.priority
 		)?;
 		if self.same_node {
@@ -113,6 +122,7 @@ fn retry_to_time(retries: u32, max_time: Duration) -> Duration {
 }
 
 fn parse_tricot_tag(
+	service_name: String,
 	tag: &str,
 	target_addr: SocketAddr,
 	add_headers: &[(String, String)],
@@ -148,6 +158,7 @@ fn parse_tricot_tag(
 	};
 
 	Some(ProxyEntry {
+		service_name,
 		target_addr,
 		https_target: (splits[0] == "tricot-https"),
 		host,
@@ -178,7 +189,7 @@ fn parse_consul_catalog(
 
 	let mut entries = vec![];
 
-	for (_, svc) in catalog.services.iter() {
+	for (service_name, svc) in catalog.services.iter() {
 		let ip_addr = match svc.address.parse() {
 			Ok(ip) => ip,
 			_ => match catalog.node.address.parse() {
@@ -210,7 +221,14 @@ fn parse_consul_catalog(
 		}
 
 		for tag in svc.tags.iter() {
-			if let Some(ent) = parse_tricot_tag(tag, addr, &add_headers[..], same_node, same_site) {
+			if let Some(ent) = parse_tricot_tag(
+				service_name.clone(),
+				tag,
+				addr,
+				&add_headers[..],
+				same_node,
+				same_site,
+			) {
 				entries.push(ent);
 			}
 		}
@@ -239,6 +257,7 @@ pub fn spawn_proxy_config_task(
 		entries: Vec::new(),
 	}));
 
+	let metrics = ProxyConfigMetrics::new(rx.clone());
 	let consul = Arc::new(consul);
 
 	tokio::spawn(async move {
@@ -348,11 +367,46 @@ pub fn spawn_proxy_config_task(
 
 			tx.send(Arc::new(config)).expect("Internal error");
 		}
+
+		drop(metrics); // ensure Metrics lives up to here
 	});
 
 	rx
 }
 
+// ----
+
+struct ProxyConfigMetrics {
+	_proxy_config_entries: metrics::ValueObserver<u64>,
+}
+
+impl ProxyConfigMetrics {
+	fn new(rx: watch::Receiver<Arc<ProxyConfig>>) -> Self {
+		let meter = opentelemetry::global::meter("tricot");
+		Self {
+			_proxy_config_entries: meter
+				.u64_value_observer("proxy_config_entries", move |observer| {
+					let mut patterns = HashMap::new();
+					for ent in rx.borrow().entries.iter() {
+						let pat = format!(
+							"{}{}",
+							ent.host,
+							ent.path_prefix.as_deref().unwrap_or_default()
+						);
+						*patterns.entry(pat).or_default() += 1;
+					}
+					for (pat, num) in patterns {
+						observer.observe(num, &[KeyValue::new("host", pat)]);
+					}
+				})
+				.with_description("Number of proxy entries (back-ends) configured in Tricot")
+				.init(),
+		}
+	}
+}
+
+// ----
+
 #[cfg(test)]
 mod tests {
 	use super::*;