apache/seatunnel · error · OptionValidationException

nodes[ ]: host must not be blank in 'host:port', got

Error message

nodes[%d]: host must not be blank in 'host:port', got: %s

What it means

Redis connector validation of the `nodes` option failed because a node entry in 'host:port' format has a blank host part (e.g. ':6379'). The RedisNodesValidator parses each node string, splits it at the first colon, and rejects entries whose host portion is empty or whitespace-only. This fail-fast check prevents later connection failures with confusing Jedis errors.

Solutions

  1. Set a non-blank hostname before the colon for every node entry (e.g. '127.0.0.1:6379').
  2. If the host comes from an env var or placeholder, verify it is set and non-empty at config-render time.
  3. Check for stray commas or whitespace in the nodes list producing an empty host segment.
  4. Run the validation before job submission by inspecting the rendered config JSON.

Example fix

// before
nodes = [":6379"]
// after
nodes = ["127.0.0.1:6379"]
Defensive patterns

Strategy: validation

Validate before calling

for (String node : nodes) {
    int colon = node.indexOf(':');
    if (colon <= 0 || node.substring(0, colon).trim().isEmpty()) {
        throw new IllegalArgumentException("node host blank: " + node);
    }
}

Prevention

When it happens

Trigger: Calling the validator's evaluate() with a nodes list where any entry is ':6379', ' :6379', or otherwise has no text before the colon; typically caused by a typo or an empty env-variable substitution in the host portion.

Common situations: Users templating config with env vars like ${REDIS_HOST}:6379 where REDIS_HOST is unset, copy-paste of cluster node lists with a leading comma producing an empty host, or hand-edited config dropping the hostname.

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.

Related errors

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/3e04caf6ca7d2893. Report an issue: GitHub.

Appendix: source

Thrown at seatunnel-connectors-v2/connector-redis/src/main/java/org/apache/seatunnel/connectors/seatunnel/redis/config/RedisNodesValidator.java:52

                + RedisBaseOptions.MIN_PORT
                + ", "
                + RedisBaseOptions.MAX_PORT
                + "]";
    }

    @Override
    public boolean evaluate(ReadonlyConfig config, List<String> value)
            throws OptionValidationException {
        for (int i = 0; i < value.size(); i++) {
            String node = value.get(i);
            if (node == null || !NODE_PATTERN.matcher(node).matches()) {
                throw new OptionValidationException(
                        "nodes[%d]: must be in 'host:port' format, got: %s", i, node);
            }
            int colon = node.indexOf(':');
            String host = node.substring(0, colon);
            if (host.trim().isEmpty()) {
                throw new OptionValidationException(
                        "nodes[%d]: host must not be blank in 'host:port', got: %s", i, node);
            }
            String portStr = node.substring(colon + 1);
            int port;
            try {
                port = Integer.parseInt(portStr);
            } catch (NumberFormatException e) {
                throw new OptionValidationException(
                        "nodes[%d]: port '%s' is out of range [%d, %d]",
                        i, portStr, RedisBaseOptions.MIN_PORT, RedisBaseOptions.MAX_PORT);
            }
            if (port < RedisBaseOptions.MIN_PORT || port > RedisBaseOptions.MAX_PORT) {
                throw new OptionValidationException(
                        "nodes[%d]: port %d is out of range [%d, %d]",
                        i, port, RedisBaseOptions.MIN_PORT, RedisBaseOptions.MAX_PORT);
            }
        }
        return true;

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