apache/shenyu · error · IllegalArgumentException

Host is empty in Redis node URL: " + url

Error message

Host is empty in Redis node URL: " + url

What it means

After parsing host and port from a Redis node URL, parseRedisNode checks that the extracted host is not blank. An empty host means the URL was malformed (e.g. ':6379') so it throws IllegalArgumentException. This ensures RedisNode is never created with an empty hostname.

Solutions

1. Provide a non-empty host for every configured node, e.g. '127.0.0.1:6379'
2. Filter out blank entries before parsing the node list
3. Check environment variable/placeholder resolution so the host is actually substituted
4. Validate the nodes configuration at startup before building the connection factory

Example fix

// before
shenyu.redis.nodes=${REDIS_HOST}:6379  // REDIS_HOST unset -> ':6379'
// after
shenyu.redis.nodes=127.0.0.1:6379

boolean hasHost(String url) {
    if (url == null) return false;
    String t = url.trim();
    int i = t.lastIndexOf(':');
    return i > 0 && !t.substring(0, i).trim().isEmpty();
}

try {
    RedisNode node = factory.parseRedisNode(url);
} catch (IllegalArgumentException e) {
    log.error("redis node missing host: {}", url);
}

When it happens

Trigger: A node URL whose host portion is empty or whitespace after colon-splitting, e.g. ' :6379' or ':6379 ' passed into redisNode/createRedisNode.

Common situations: Empty or blank entries in a comma-separated node list in cluster/sentinel configuration, unresolved placeholder like '${redis.host}:6379' leaving the host blank in some environments.

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

• Redis node URL cannot be null or empty
• Port cannot be empty in Redis node URL: " + url
• client register param must config the appName or contextPath
• The configuration shenyu.discovery.serverList in xml/yml…
• OpenAPI pathKey cannot be null or empty

AI-assisted analysis of apache/shenyu@567142e072 (2026-09-12). Data as JSON: /api/errors/b817a0055a22c499. Report an issue: GitHub.

Appendix: source

Thrown at shenyu-infra/shenyu-infra-redis/src/main/java/org/apache/shenyu/infra/redis/RedisConnectionFactory.java:192

            int lastColonIndex = trimmedUrl.lastIndexOf(":");
            if (lastColonIndex > 0 && lastColonIndex < trimmedUrl.length() - 1) {
                String portStr = trimmedUrl.substring(lastColonIndex + 1);
                if (portStr.isEmpty()) {
                    throw new IllegalArgumentException("Port cannot be empty in Redis node URL: " + url);
                }
                try {
                    port = Integer.parseInt(portStr);
                } catch (NumberFormatException e) {
                    throw new IllegalArgumentException("Invalid port in Redis node URL: " + url, e);
                }
                host = trimmedUrl.substring(0, lastColonIndex);
            } else if (lastColonIndex == 0 || lastColonIndex == trimmedUrl.length() - 1) {
                throw new IllegalArgumentException("Invalid format in Redis node URL: " + url);
            }
        }
        
        if (host.trim().isEmpty()) {
            throw new IllegalArgumentException("Host is empty in Redis node URL: " + url);
        }
        if (port < 1 || port > 65535) {
            throw new IllegalArgumentException("Port out of range (1-65535) in Redis node URL: " + url);
        }
        
        return new RedisNode(host.trim(), port);
    }
}

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