failed to lookup address information

async fn upstream_peer(&self, s: &mut Session, _: &mut ()) -> Result<Box<HttpPeer>> {
  let path = s.req_header().uri.path().to_string();
  let peer = if path == "/slow" {
    HttpPeer::new(SlowResolve("127.0.0.1:19301"), false, String::new())
  } else {
    HttpPeer::new(target(&path), false, String::new())
  };
  Ok(Box::new(peer))
}

--- /fast
/fast 200 0.005276s exit=0
--- /slow, /fast 100ms later
/fast 200 0.900896s exit=0
/slow 200 1.007557s exit=0
--- /name
/name 502 0.003445s exit=0
--- /bad
/bad 000 0.011830s exit=52
--- /fast
/fast 200 0.001863s exit=0

/name: HttpPeer::new took 2.466417ms, addr [::1]:19301
[2026-10-29T06:37:13Z ERROR pingora_proxy] Fail to proxy: Upstream ConnectRefused context: Fail to connect to addr: [::1]:19301, scheme: HTTP cause:  context: Fail to connect to [::1]:19301 cause: Connection refused (os error 61), status: 502, tries: 1, retry: false, GET /name, Host: 127.0.0.1:19300

thread 'Pingora HTTP Proxy Service' (5857449) panicked at ~/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/pingora-core-0.9.0/src/upstreams/peer.rs:719:56:
called `Result::unwrap()` on an `Err` value: Custom { kind: Uncategorized, error: "failed to lookup address information: nodename nor servname provided, or not known" }

    pub fn new<A: ToInetSocketAddrs>(address: A, tls: bool, sni: String) -> Self {
        let mut addrs_iter = address.to_socket_addrs().unwrap(); //TODO: handle error
        let addr = addrs_iter.next().unwrap();
        Self::new_from_sockaddr(SocketAddr::Inet(addr), tls, sni)
    }

async fn upstream_peer(&self, s: &mut Session, ctx: &mut Ctx) -> Result<Box<HttpPeer>> {
  let path = s.req_header().uri.path().to_string();
  if ctx.addrs.is_empty() {
    let r: std::io::Result<Vec<SocketAddr>> = if path == "/slow" {
      // the same blocking resolver, moved to tokio's blocking pool
      match tokio::task::spawn_blocking(|| SlowResolve("127.0.0.1:19301").to_socket_addrs()).await {
        Ok(r) => r.map(|i| i.collect()),
        Err(e) => Err(std::io::Error::other(e)),
      }
    } else {
      tokio::net::lookup_host(target(&path)).await.map(|i| i.collect())
    };
    // into_up(): an upstream-side error, so fail_to_proxy answers 502 instead of 500
    ctx.addrs = r.map_err(|e| Error::explain(ErrorType::ConnectNoRoute, format!("resolve {}: {e}", target(&path))).into_up())?;
  }
  let addr = ctx.addrs.get(ctx.next).copied().ok_or_else(|| Error::explain(ErrorType::ConnectNoRoute, "no address left"))?;
  ctx.next += 1;
  Ok(Box::new(HttpPeer::new(addr, false, String::new())))
}

fn fail_to_connect(&self, _s: &mut Session, _p: &HttpPeer, ctx: &mut Ctx, mut e: Box<Error>) -> Box<Error> {
  // nothing was sent yet, so trying the next address is safe for every method
  if ctx.next < ctx.addrs.len() {
    e.set_retry(true);
  }
  e
}

--- /fast
/fast 200 0.003651s exit=0
--- /slow, /fast 100ms later
/fast 200 0.002536s exit=0
/slow 200 1.007358s exit=0
--- /name
/name 200 0.005888s exit=0
--- /bad
/bad 502 0.008119s exit=0
--- /fast
/fast 200 0.002083s exit=0

/name: resolved [[::1]:19301, 127.0.0.1:19301] in 3.587959ms
/name: try [::1]:19301
[2026-10-29T06:37:35Z WARN  pingora_proxy] Fail to proxy: Upstream ConnectRefused context: Fail to connect to addr: [::1]:19301, scheme: HTTP cause:  context: Fail to connect to [::1]:19301 cause: Connection refused (os error 61), tries: 1, retry: true, GET /name, Host: 127.0.0.1:19300
/name: try 127.0.0.1:19301
[2026-10-29T06:37:35Z ERROR pingora_proxy] Fail to proxy: Upstream ConnectNoRoute context: resolve no-such-host.invalid:80: failed to lookup address information: nodename nor servname provided, or not known, status: 502, tries: 1, retry: false, GET /bad, Host: 127.0.0.1:19300