nikivdev/code · error · anyhow::Error

Host is empty

Error message

Host is empty

What it means

normalize_host sanitizes user-supplied host input before route operations. After stripping scheme prefixes and trailing slashes, if nothing remains the function bails because an empty host cannot be a valid route key.

Source

Thrown at src/domains.rs:278

        println!("{}", "-".repeat(58));
        for (host, target) in routes {
            println!("{:<32} {}", host, target);
        }
    }

    Ok(())
}

fn normalize_host(raw: &str) -> Result<String> {
    let mut host = raw.trim().to_ascii_lowercase();
    if let Some(stripped) = host.strip_prefix("http://") {
        host = stripped.to_string();
    } else if let Some(stripped) = host.strip_prefix("https://") {
        host = stripped.to_string();
    }
    host = host.trim_end_matches('/').to_string();
    if host.is_empty() {
        bail!("Host is empty");
    }
    if host.contains('/') || host.contains(':') || host.contains(char::is_whitespace) {
        bail!("Host must be a hostname like linsa.localhost");
    }
    if !host.ends_with(".localhost") {
        bail!("Host must end with .localhost");
    }
    if host == ".localhost" || host == "localhost" {
        bail!("Host must include a subdomain (for example: linsa.localhost)");
    }
    Ok(host)
}

fn normalize_target(raw: &str) -> Result<String> {
    let mut target = raw.trim().to_string();
    if let Some(stripped) = target.strip_prefix("http://") {
        target = stripped.to_string();
    } else if let Some(stripped) = target.strip_prefix("https://") {

View on GitHub (pinned to a747e741ae)

Solutions

1. Pass a full hostname such as linsa.localhost
2. Check that the shell variable holding the host is actually set/non-empty
3. Quote the argument so empty expansions fail loudly instead of vanishing

Example fix

// before
f domains add "$HOST" :3000   # HOST empty -> Host is empty
// after
f domains add "linsa.localhost" :3000

let host = raw.trim();
let host = host.trim_start_matches("http://").trim_start_matches("https://").trim_end_matches('/');
if host.is_empty() {
    return Err("host argument required, e.g. linsa.localhost");
}

When it happens

Trigger: Passing an empty string, only a scheme ("http://"), only slashes ("/"), or only whitespace to domains get/add/rm — everything is stripped and the result is empty.

Common situations: Shell variable expansion failing ($HOST unset), copy-pasting just "https://", or scripting the command with a missing argument that defaults to empty.

Related errors

• Host must be a hostname like linsa.localhost
• Query cannot be empty
• Host must end with .localhost
• Host must include a subdomain (for example: linsa.localhost)
• lifecycle.domains.aliases[].host is required

AI-assisted analysis of nikivdev/code@a747e741ae (2026-09-01). Data as JSON: /api/errors/09f0f0c5b7e7a597. Report an issue: GitHub.