First commit to Tricot, a replacement for Traefik v1

.gitignore

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+/target

Cargo.toml

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+[package]
+name = "tricot"
+version = "0.1.0"
+edition = "2018"
+authors = ["Alex Auvolat <alex@adnab.me>"]
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+anyhow = "1.0.28"
+envy = "0.4"
+futures = "0.3.5"
+log = "0.4"
+pretty_env_logger = "0.4"
+regex = "1"
+reqwest = { version = "0.11", features = ["json"] }
+serde = { version = "1.0.107", features = ["derive"] }
+serde_json = "1.0.53"
+tokio = { version = "1.0", default-features = false, features = ["rt", "rt-multi-thread", "io-util", "net", "time", "macros", "sync", "signal", "fs"] }

Makefile

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+all:
+	clear; cargo build
+

rustfmt.toml

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+hard_tabs = true

src/consul.rs

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+use std::collections::HashMap;
+
+use anyhow::Result;
+use log::*;
+use serde::{Deserialize, Serialize};
+
+// ---- Watch and retrieve Consul catalog ----
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct ConsulServiceEntry {
+	#[serde(rename = "Address")]
+	pub address: String,
+
+	#[serde(rename = "Port")]
+	pub port: u16,
+
+	#[serde(rename = "Tags")]
+	pub tags: Vec<String>,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct ConsulNodeCatalog {
+	#[serde(rename = "Services")]
+	pub services: HashMap<String, ConsulServiceEntry>,
+}
+
+#[derive(Clone)]
+pub struct Consul {
+	client: reqwest::Client,
+	url: String,
+	idx: Option<u64>,
+}
+
+impl Consul {
+	pub fn new(url: &str) -> Self {
+		return Self {
+			client: reqwest::Client::new(),
+			url: url.to_string(),
+			idx: None,
+		};
+	}
+
+	pub fn watch_node_reset(&mut self) -> () {
+		self.idx = None;
+	}
+
+	pub async fn watch_node(&mut self, host: &str) -> Result<ConsulNodeCatalog> {
+		let url = match self.idx {
+			Some(i) => format!("{}/v1/catalog/node/{}?index={}", self.url, host, i),
+			None => format!("{}/v1/catalog/node/{}", self.url, host),
+		};
+
+		let http = self.client.get(&url).send().await?;
+		self.idx = match http.headers().get("X-Consul-Index") {
+			Some(v) => Some(v.to_str()?.parse::<u64>()?),
+			None => return Err(anyhow!("X-Consul-Index header not found")),
+		};
+
+		let resp: ConsulNodeCatalog = http.json().await?;
+		return Ok(resp);
+	}
+}

src/main.rs

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+#[macro_use]
+extern crate anyhow;
+
+mod consul;
+mod proxy_config;
+
+use log::*;
+
+#[tokio::main]
+async fn main() {
+	pretty_env_logger::init();
+	info!("Starting Tricot");
+
+	let consul = consul::Consul::new("http://10.42.0.21:8500");
+	let mut rx_proxy_config = proxy_config::spawn_proxy_config_task(consul.clone(), "carcajou");
+
+	while rx_proxy_config.changed().await.is_ok() {
+		info!("Proxy config: {:#?}", *rx_proxy_config.borrow());
+	}
+}

src/proxy_config.rs

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+use std::net::SocketAddr;
+use std::{cmp, time::Duration};
+
+use log::*;
+use tokio::{sync::watch, time::sleep};
+
+use crate::consul::*;
+
+// ---- Extract proxy config from Consul catalog ----
+
+#[derive(Debug)]
+pub struct ProxyEntry {
+	pub target_addr: SocketAddr,
+	pub host: String,
+	pub path_prefix: Option<String>,
+	pub priority: u32,
+}
+
+#[derive(Debug)]
+pub struct ProxyConfig {
+	pub entries: Vec<ProxyEntry>,
+}
+
+fn retry_to_time(retries: u32, max_time: Duration) -> Duration {
+	// 1.2^x seems to be a good value to exponentially increase time at a good pace
+	// eg. 1.2^32 = 341 seconds ~= 5 minutes - ie. after 32 retries we wait 5
+	// minutes
+	return Duration::from_secs(cmp::min(
+		max_time.as_secs(),
+		1.2f64.powf(retries as f64) as u64,
+	));
+}
+
+fn parse_tricot_tag(target_addr: SocketAddr, tag: &str) -> Option<ProxyEntry> {
+	let splits = tag.split(' ').collect::<Vec<_>>();
+	if (splits.len() != 2 && splits.len() != 3) || splits[0] != "tricot" {
+		return None;
+	}
+
+	let (host, path_prefix) = match splits[1].split_once('/') {
+		Some((h, p)) => (h, Some(p.to_string())),
+		None => (splits[1], None),
+	};
+
+	let priority = match splits.len() {
+		3 => splits[2].parse().ok()?,
+		_ => 100,
+	};
+
+	Some(ProxyEntry {
+		target_addr,
+		host: host.to_string(),
+		path_prefix,
+		priority,
+	})
+}
+
+fn parse_consul_catalog(catalog: &ConsulNodeCatalog) -> ProxyConfig {
+	let mut entries = vec![];
+
+	for (_, svc) in catalog.services.iter() {
+		let ip_addr = match svc.address.parse() {
+			Ok(ip) => ip,
+			_ => continue,
+		};
+		let addr = SocketAddr::new(ip_addr, svc.port);
+		for tag in svc.tags.iter() {
+			if let Some(ent) = parse_tricot_tag(addr, tag) {
+				entries.push(ent);
+			}
+		}
+	}
+
+	ProxyConfig { entries }
+}
+
+pub fn spawn_proxy_config_task(mut consul: Consul, node: &str) -> watch::Receiver<ProxyConfig> {
+	let (tx, rx) = watch::channel(ProxyConfig {
+		entries: Vec::new(),
+	});
+
+	let node = node.to_string();
+
+	tokio::spawn(async move {
+		let mut retries = 0;
+
+		loop {
+			let catalog = match consul.watch_node(&node).await {
+				Ok(c) => c,
+				Err(e) => {
+					consul.watch_node_reset();
+					retries = cmp::min(std::u32::MAX - 1, retries) + 1;
+					let will_retry_in = retry_to_time(retries, Duration::from_secs(600));
+					error!(
+						"Failed to query consul. Will retry in {}s. {}",
+						will_retry_in.as_secs(),
+						e
+					);
+					sleep(will_retry_in).await;
+					continue;
+				}
+			};
+			retries = 0;
+
+			let config = parse_consul_catalog(&catalog);
+			debug!("Extracted configuration: {:#?}", config);
+
+			tx.send(config).expect("Internal error");
+		}
+	});
+
+	rx
+}