apache/druid · error · IllegalArgumentException

Conflicting host:port

Error message

Conflicting host:port [%s] and port [%d] settings

What it means

DruidNode allows the host property to embed a port (host:port form). If the embedded port in druid.host conflicts with the separately configured plaintext port, init() throws IAE because the two settings disagree.

Solutions

  1. Make druid.host contain no port and rely on druid.port alone
  2. Make the port embedded in druid.host exactly match druid.port
  3. Fix the templating variables so host and port derive from one source

Example fix

// before
  druid.host=node1.example.com:8080
  druid.port=8081
// after
  druid.host=node1.example.com
  druid.port=8081
Defensive patterns

Strategy: validation

Validate before calling

HostAndPort hap = HostAndPort.fromString(druidHost);
if (hap.hasPort() && hap.getPort() != druidPort) {
  throw new IllegalArgumentException("druid.host port " + hap.getPort()
      + " conflicts with druid.port " + druidPort);
}

Try / catch

try {
  node = new DruidNode(service, druidHost, true, druidPort, tlsPort, false, false);
} catch (IllegalArgumentException e) {
  log.fatal("Conflicting host:port settings: %s", e.getMessage());
  throw e;
}

Prevention

When it happens

Trigger: Setting druid.host=myhost:8080 while druid.port (plaintextPort) is set to a different value, e.g. 8081; host strings with stale ports left after config refactors.

Common situations: Config templating that appends a fixed port to druid.host while druid.port comes from another variable; copy-paste of host entries from other clusters.

Understand the failure class

Background: Conflicting config options: "cannot be used together" — configuration validation errors across open-source libraries — this error's family across 162 libraries.

Related errors

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/f97a929597617b6a. Report an issue: GitHub.

Appendix: source

Thrown at server/src/main/java/org/apache/druid/server/DruidNode.java:185

  {
    Preconditions.checkNotNull(serviceName);

    if (!enableTlsPort && !enablePlaintextPort) {
      throw new IAE("At least one of the druid.enablePlaintextPort or druid.enableTlsPort needs to be true.");
    }

    this.enablePlaintextPort = enablePlaintextPort;
    this.enableTlsPort = enableTlsPort;

    final boolean nullHost = host == null;
    HostAndPort hostAndPort;
    Integer portFromHostConfig;
    if (host != null) {
      hostAndPort = HostAndPort.fromString(host);
      host = hostAndPort.getHost();
      portFromHostConfig = hostAndPort.hasPort() ? hostAndPort.getPort() : null;
      if (plainTextPort != null && portFromHostConfig != null && !plainTextPort.equals(portFromHostConfig)) {
        throw new IAE("Conflicting host:port [%s] and port [%d] settings", host, plainTextPort);
      }
      if (portFromHostConfig != null) {
        plainTextPort = portFromHostConfig;
      }
    } else {
      host = getDefaultHost();
    }

    if (enablePlaintextPort && enableTlsPort && ((plainTextPort == null || tlsPort == null)
                                                 || plainTextPort.equals(tlsPort))) {
      // If both plainTExt and tls are enabled then do not allow plaintextPort to be null or
      throw new IAE("plaintextPort and tlsPort cannot be null or same if both http and https connectors are enabled");
    }
    if (enableTlsPort && (tlsPort == null || tlsPort < 0)) {
      throw new IAE("A valid tlsPort needs to specified when druid.enableTlsPort is set");
    }

    if (enablePlaintextPort) {

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