t8y2/dbx · error · IllegalArgumentException

ZooKeeper did not return any usable Kafka broker endpoints

Error message

ZooKeeper did not return any usable Kafka broker endpoints

What it means

Thrown by brokerEndpoints during ZooKeeper-based discovery when broker registrations under /brokers/ids yielded no usable host:port endpoint for the configured security protocol — e.g. all listeners were filtered by protocol mismatch or registrations lacked connectable address fields. Discovery produces an empty endpoint set, so bootstrap server resolution fails.

Solutions

1. Check that the Kafka brokers advertise listeners matching the agent's security_protocol setting (e.g. PLAINTEXT vs SSL)
2. Inspect a broker registration in ZooKeeper (/brokers/ids/<id>) and confirm its listener endpoints contain valid host and port
3. Ensure advertised.listeners on the brokers includes a listener reachable from the agent host
4. Fall back to explicit bootstrap_servers configuration

When it happens

Trigger: Thrown at agents/drivers/kafka/src/main/java/com/dbx/agent/kafka/KafkaAgent.java:445 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of t8y2/dbx@c0390bff16 (2026-09-05). Data as JSON: /api/errors/cc9efd45418553c6. Report an issue: GitHub.

Appendix: source

Thrown at agents/drivers/kafka/src/main/java/com/dbx/agent/kafka/KafkaAgent.java:445

                    : listener;
                if (!targetProtocol.equals(mappedProtocol)) continue;
                String address = endpointAddress(endpoint);
                if (address != null) addresses.add(address);
            }

            if (addresses.size() == addressCount && endpoints.size() == 0 && registration.has("host") && registration.has("port")) {
                try {
                    String host = registration.get("host").getAsString().trim();
                    int port = registration.get("port").getAsInt();
                    if (!host.isEmpty() && port > 0 && port <= 65535) addresses.add(formatHostPort(host, port));
                } catch (RuntimeException e) {
                    logger().warn("Skipping malformed legacy Kafka broker registration", e);
                }
            }
        }

        if (addresses.isEmpty()) {
            throw new IllegalArgumentException("ZooKeeper did not return any usable Kafka broker endpoints");
        }
        return String.join(",", addresses);
    }

    private static String endpointAddress(String endpoint) {
        try {
            URI uri = URI.create(endpoint);
            String host = uri.getHost();
            int port = uri.getPort();
            if (host == null || host.isBlank() || port <= 0 || port > 65535) return null;
            return formatHostPort(host, port);
        } catch (IllegalArgumentException e) {
            logger().debug("Skipping malformed Kafka broker endpoint", e);
            return null;
        }
    }

    private static String formatHostPort(String host, int port) {

View on GitHub (pinned to c0390bff16)