quickwit-oss/quickwit · error

failed to parse address `{}`: hostname is invalid

Error message

failed to parse address `{}`: hostname is invalid

What it means

`HostAddr::parse_with_default_port` parses `<host>:<port>` strings (with an optional default port when the port is omitted). After extracting the hostname and port, it re-validates the hostname with `is_valid_hostname`; if the hostname part fails validation it rejects the whole address with this error, even though the string may have split cleanly.

Source

Thrown at quickwit/quickwit-common/src/net.rs:169

                port: socket_addr.port(),
            });
        }
        if let Ok(ip_addr) = host_addr.parse::<IpAddr>() {
            return Ok(Self {
                host: Host::IpAddr(ip_addr),
                port: default_port,
            });
        }
        let (hostname, port) = if let Some((hostname_str, port_str)) = host_addr.split_once(':') {
            let port_u16 = port_str.parse::<u16>().with_context(|| {
                format!("failed to parse address `{host_addr}`: port is invalid")
            })?;
            (hostname_str, port_u16)
        } else {
            (host_addr, default_port)
        };
        if !is_valid_hostname(hostname) {
            bail!(
                "failed to parse address `{}`: hostname is invalid",
                host_addr
            )
        }
        Ok(Self {
            host: Host::Hostname(hostname.to_string()),
            port,
        })
    }

    /// Resolves the host if necessary and returns a `SocketAddr`.
    pub async fn resolve(&self) -> anyhow::Result<SocketAddr> {
        self.host
            .resolve()
            .await
            .map(|ip_addr| SocketAddr::new(ip_addr, self.port))
    }

View on GitHub (pinned to a39730c5cd)

Solutions

1. Correct the hostname portion to valid DNS syntax (alphanumerics and hyphens only) and re-parse.
2. For IPv6 hosts, wrap the address in brackets: `[::1]:7200` instead of `::1:7200`.
3. If an IP was intended, verify the IP syntax — a malformed IP falls through to hostname validation and fails there.
4. Ensure the value is `host` or `host:port` with no extra separators, spaces, or scheme prefix (`http://` must be stripped).

Example fix

// before
let addr: HostAddr = "node_1:7200".parse()?; // invalid hostname
// after
let addr: HostAddr = "node-1:7200".parse()?;

fn parse_addr_checked(s: &str, default_port: u16) -> Result<quickwit_common::net::HostAddr, String> {
    let s = s.trim();
    let host_part = s.rsplit_once(':').map(|(h, _)| h).unwrap_or(s);
    if host_part.contains('_') {
        return Err(format!("hostname '{host_part}' contains invalid characters (use hyphens)"));
    }
    s.parse::<quickwit_common::net::HostAddr>().map_err(|e| e.to_string())
}

match addr_str.parse::<quickwit_common::net::HostAddr>() {
    Ok(addr) => use_addr(addr),
    Err(e) if e.to_string().contains("hostname is invalid") => {
        // hint user: check host portion syntax, bracket IPv6
    }
    Err(e) => return Err(e),
}

When it happens

Trigger: Parsing an address string whose host portion is not a valid DNS hostname — e.g. `"my_node:7200"` (underscore in host), `"-node:7200"`, an over-long label, or an empty host like `":7200"` — via `HostAddr::from_str` or config fields expecting `host:port`.

Common situations: Malformed `peer_address`/`advertise_address`/gRPC listen addresses in quickwit.yaml, hostnames containing underscores generated by container orchestrators, IPv6 addresses without brackets (`::1:7200` parses the wrong part as hostname), or pasting addresses with hidden whitespace.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• failed to parse host: `{host}`
• IP range should parse
• no server currently available
• unknown URI protocol `{protocol}`
• index ID pattern `{pattern}` is invalid: patterns must not c

AI-assisted analysis of quickwit-oss/quickwit@a39730c5cd (2026-09-08). Data as JSON: /api/errors/e229b4a0e5856a13. Report an issue: GitHub.