more reliable mdns setup

Cargo.lock

@@ -28,6 +28,15 @@ dependencies = [
  "version_check",
 ]
 
+[[package]]
+name = "ansi_term"
+version = "0.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d52a9bb7ec0cf484c551830a7ce27bd20d67eac647e1befb56b0be4ee39a55d2"
+dependencies = [
+ "winapi",
+]
+
 [[package]]
 name = "autocfg"
 version = "1.1.0"
@@ -780,6 +789,8 @@ dependencies = [
  "once_cell",
  "regex",
  "tokio",
+ "tracing",
+ "tracing-subscriber",
  "warp",
 ]
 
@@ -1042,6 +1053,12 @@ version = "0.4.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "eb703cfe953bccee95685111adeedb76fabe4e97549a58d16f03ea7b9367bb32"
 
+[[package]]
+name = "smallvec"
+version = "1.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f2dd574626839106c320a323308629dcb1acfc96e32a8cba364ddc61ac23ee83"
+
 [[package]]
 name = "socket2"
 version = "0.4.4"
@@ -1223,9 +1240,21 @@ dependencies = [
  "cfg-if",
  "log",
  "pin-project-lite",
+ "tracing-attributes",
  "tracing-core",
 ]
 
+[[package]]
+name = "tracing-attributes"
+version = "0.1.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cc6b8ad3567499f98a1db7a752b07a7c8c7c7c34c332ec00effb2b0027974b7c"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "tracing-core"
 version = "0.1.28"
@@ -1246,15 +1275,29 @@ dependencies = [
  "tracing-subscriber",
 ]
 
+[[package]]
+name = "tracing-log"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "78ddad33d2d10b1ed7eb9d1f518a5674713876e97e5bb9b7345a7984fbb4f922"
+dependencies = [
+ "lazy_static",
+ "log",
+ "tracing-core",
+]
+
 [[package]]
 name = "tracing-subscriber"
 version = "0.3.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4bc28f93baff38037f64e6f43d34cfa1605f27a49c34e8a04c5e78b0babf2596"
 dependencies = [
+ "ansi_term",
  "sharded-slab",
+ "smallvec",
  "thread_local",
  "tracing-core",
+ "tracing-log",
 ]
 
 [[package]]

Cargo.toml

@@ -18,6 +18,8 @@ ahash = "0.7"
 bollard = "0.13.0"
 futures-util = "0.3"
 libmdns = "0.7"
+tracing = "0.1.33"
+tracing-subscriber = "0.3.11"
 
 [dev-dependencies]
 iai = "0.1"

src/main.rs

@@ -7,7 +7,11 @@ use palantir::docker::{get_docker, stat, Container};
 use palantir::get_metrics;
 use palantir::power::power_usage;
 use palantir::zfs::arcstats;
+use std::time::Duration;
 use tokio::runtime::Handle;
+use tokio::spawn;
+use tokio::time::sleep;
+use tracing::warn;
 use warp::reject::Reject;
 use warp::{Filter, Rejection};
 
@@ -52,6 +56,8 @@ async fn serve_metrics(docker: Option<Docker>) -> Result<String, Rejection> {
 
 #[tokio::main]
 async fn main() -> Result<()> {
+    tracing_subscriber::fmt::init();
+
     let host_port: u16 = dotenv::var("PORT")
         .ok()
         .map(|port| port.parse())
@@ -66,16 +72,36 @@ async fn main() -> Result<()> {
     let docker = get_docker().await;
     let docker = warp::any().map(move || docker.clone());
 
-    let mdns = Responder::spawn(&Handle::current())?;
-    let _svc = mdns.register(
-        "_prometheus-http._tcp".into(),
+    spawn(setup_mdns(
         hostname::get()?.into_string().unwrap(),
         host_port,
-        &[&"/metrics"],
-    );
+    ));
 
     let metrics = warp::path!("metrics").and(docker).and_then(serve_metrics);
 
     warp::serve(metrics).run(([0, 0, 0, 0], host_port)).await;
     Ok(())
 }
+
+async fn setup_mdns(hostname: String, port: u16) {
+    let mdns = loop {
+        match Responder::spawn(&Handle::current()) {
+            Ok(mdns) => break mdns,
+            Err(e) => {
+                warn!(error = display(e), "Failed to register mdns responder");
+                sleep(Duration::from_secs(5)).await;
+            }
+        }
+    };
+
+    let _svc = mdns.register(
+        "_prometheus-http._tcp".into(),
+        hostname,
+        port,
+        &[&"/metrics"],
+    );
+
+    loop {
+        sleep(Duration::from_secs(60 * 60)).await;
+    }
+}