From ced324bc876eb592c0ed4aea889827c0000cf9ad Mon Sep 17 00:00:00 2001
From: Alex Auvolat <alex@adnab.me>
Date: Thu, 13 Jan 2022 11:31:08 +0100
Subject: Make nodes aware of where they are and use that to priorize backends

---
 src/consul.rs       |  6 ++++--
 src/https.rs        |  2 ++
 src/proxy_config.rs | 59 +++++++++++++++++++++++++++++++++++++++++++++--------
 3 files changed, 56 insertions(+), 11 deletions(-)

diff --git a/src/consul.rs b/src/consul.rs
index 14df1ee..cba435a 100644
--- a/src/consul.rs
+++ b/src/consul.rs
@@ -23,6 +23,8 @@ pub struct ConsulNode {
 	pub node: String,
 	#[serde(rename = "Address")]
 	pub address: String,
+	#[serde(rename = "Meta")]
+	pub meta: HashMap<String, String>,
 }
 
 #[derive(Serialize, Deserialize, Debug)]
@@ -117,14 +119,14 @@ impl Consul {
 		})
 	}
 
-	pub async fn list_nodes(&self) -> Result<Vec<String>> {
+	pub async fn list_nodes(&self) -> Result<Vec<ConsulNode>> {
 		debug!("list_nodes");
 
 		let url = format!("{}/v1/catalog/nodes", self.url);
 
 		let http = self.client.get(&url).send().await?;
 		let resp: Vec<ConsulNode> = http.json().await?;
-		Ok(resp.into_iter().map(|n| n.node).collect::<Vec<_>>())
+		Ok(resp)
 	}
 
 	pub async fn watch_node(
diff --git a/src/https.rs b/src/https.rs
index a9f2cc1..34e3f85 100644
--- a/src/https.rs
+++ b/src/https.rs
@@ -137,6 +137,8 @@ async fn handle(
 					.as_ref()
 					.map(|x| x.len() as i32)
 					.unwrap_or(0),
+				ent.same_node,
+				ent.same_site,
 				-ent.calls.load(Ordering::SeqCst),
 			)
 		});
diff --git a/src/proxy_config.rs b/src/proxy_config.rs
index deb2ffe..a64e5aa 100644
--- a/src/proxy_config.rs
+++ b/src/proxy_config.rs
@@ -40,12 +40,27 @@ impl HostDescription {
 
 #[derive(Debug)]
 pub struct ProxyEntry {
-	pub target_addr: SocketAddr,
-	pub https_target: bool,
-
+	/// Publicly exposed TLS hostnames for matching this rule
 	pub host: HostDescription,
+	/// Path prefix for matching this rule
 	pub path_prefix: Option<String>,
+	/// Priority with which this rule is considered (highest first)
 	pub priority: u32,
+
+	/// Node address (ip+port) to handle requests that match this entry
+	pub target_addr: SocketAddr,
+	/// Is the target serving HTTPS instead of HTTP?
+	pub https_target: bool,
+
+	/// Is the target the same node as we are running on?
+	/// (if yes priorize it over other matching targets)
+	pub same_node: bool,
+	/// Is the target the same site as this node?
+	/// (if yes priorize it over other matching targets)
+	pub same_site: bool,
+
+	/// Add the following headers to all responses returned
+	/// when matching this rule
 	pub add_headers: Vec<(String, String)>,
 
 	// Counts the number of times this proxy server has been called to
@@ -70,6 +85,11 @@ impl std::fmt::Display for ProxyEntry {
 			self.path_prefix.as_ref().unwrap_or(&String::new()),
 			self.priority
 		)?;
+		if self.same_node {
+			write!(f, " OURSELF")?;
+		} else if self.same_site {
+			write!(f, " SAME_SITE")?;
+		}
 		if !self.add_headers.is_empty() {
 			write!(f, " +Headers: {:?}", self.add_headers)?;
 		}
@@ -96,6 +116,8 @@ fn parse_tricot_tag(
 	tag: &str,
 	target_addr: SocketAddr,
 	add_headers: &[(String, String)],
+	same_node: bool,
+	same_site: bool,
 ) -> Option<ProxyEntry> {
 	let splits = tag.split(' ').collect::<Vec<_>>();
 	if (splits.len() != 2 && splits.len() != 3)
@@ -129,6 +151,8 @@ fn parse_tricot_tag(
 		target_addr,
 		https_target: (splits[0] == "tricot-https"),
 		host,
+		same_node,
+		same_site,
 		path_prefix,
 		priority,
 		add_headers: add_headers.to_vec(),
@@ -145,7 +169,11 @@ fn parse_tricot_add_header_tag(tag: &str) -> Option<(String, String)> {
 	}
 }
 
-fn parse_consul_catalog(catalog: &ConsulNodeCatalog) -> Vec<ProxyEntry> {
+fn parse_consul_catalog(
+	catalog: &ConsulNodeCatalog,
+	same_node: bool,
+	same_site: bool,
+) -> Vec<ProxyEntry> {
 	trace!("Parsing node catalog: {:#?}", catalog);
 
 	let mut entries = vec![];
@@ -174,7 +202,7 @@ fn parse_consul_catalog(catalog: &ConsulNodeCatalog) -> Vec<ProxyEntry> {
 		}
 
 		for tag in svc.tags.iter() {
-			if let Some(ent) = parse_tricot_tag(tag, addr, &add_headers[..]) {
+			if let Some(ent) = parse_tricot_tag(tag, addr, &add_headers[..], same_node, same_site) {
 				entries.push(ent);
 			}
 		}
@@ -206,12 +234,15 @@ pub fn spawn_proxy_config_task(consul: Consul) -> watch::Receiver<Arc<ProxyConfi
 		let mut nodes = HashMap::new();
 		let mut watches = FuturesUnordered::<BoxFuture<'static, (String, Result<_>)>>::new();
 
+		let mut node_site = HashMap::new();
+
 		loop {
 			match consul.list_nodes().await {
 				Ok(consul_nodes) => {
 					info!("Watched consul nodes: {:?}", consul_nodes);
-					for node in consul_nodes {
-						if !nodes.contains_key(&node) {
+					for consul_node in consul_nodes {
+						let node = &consul_node.node;
+						if !nodes.contains_key(node) {
 							nodes.insert(node.clone(), NodeWatchState::default());
 
 							let node = node.to_string();
@@ -222,6 +253,9 @@ pub fn spawn_proxy_config_task(consul: Consul) -> watch::Receiver<Arc<ProxyConfi
 								(node, res)
 							}));
 						}
+						if let Some(site) = consul_node.meta.get("site") {
+							node_site.insert(node.clone(), site.clone());
+						}
 					}
 				}
 				Err(e) => {
@@ -277,9 +311,16 @@ pub fn spawn_proxy_config_task(consul: Consul) -> watch::Receiver<Arc<ProxyConfi
 			}
 
 			let mut entries = vec![];
-			for (_, watch_state) in nodes.iter() {
+			for (node_name, watch_state) in nodes.iter() {
 				if let Some(catalog) = &watch_state.last_catalog {
-					entries.extend(parse_consul_catalog(catalog));
+					let same_node = *node_name == consul.local_node;
+					let same_site =
+						match (node_site.get(node_name), node_site.get(&consul.local_node)) {
+							(Some(s1), Some(s2)) => s1 == s2,
+							_ => false,
+						};
+
+					entries.extend(parse_consul_catalog(catalog, same_node, same_site));
 				}
 			}
 			let config = ProxyConfig { entries };
-- 
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