alibaba/druid · error · DruidRuntimeException

Please set the urlTemplate.

Error message

Please set the urlTemplate.

What it means

ZookeeperNodeListener.checkParameters() throws this when urlTemplate is empty/null. The template (e.g. jdbc:mysql://{host}:{port}/db) is used to synthesize a JDBC URL for each child node value, so the listener can feed real DataSource URLs to the PoolUpdater. Without it the HA pool cannot materialize new node connections.

Solutions

1. Call listener.setUrlTemplate("jdbc:mysql://{host}:{port}/yourdb") — must contain the {host} and {port} placeholders the listener substitutes from each znode value.
2. Confirm the JDBC scheme prefix matches a driver that is on the classpath, or the resulting URL will fail later when a connection is opened.
3. Validate the template in a startup assertion so misconfiguration surfaces at boot, not on the first node event.

Example fix

// before
ZookeeperNodeListener l = new ZookeeperNodeListener();
l.setZkConnectString("zk1:2181");
l.setPath("/druid/ha");
l.start(); // throws: urlTemplate missing

// after
l.setZkConnectString("zk1:2181");
l.setPath("/druid/ha");
l.setUrlTemplate("jdbc:mysql://{host}:{port}/orders");
l.start();

ZookeeperNodeListener z = (ZookeeperNodeListener) listener;
if (z.getUrlTemplate() == null || z.getUrlTemplate().isEmpty()) {
    throw new IllegalStateException("set urlTemplate, e.g. jdbc:mysql://{host}:{port}/db");
}
if (!z.getUrlTemplate().contains("{host}") || !z.getUrlTemplate().contains("{port}")) {
    throw new IllegalStateException("urlTemplate must contain {host} and {port} placeholders");
}

public static boolean templateConfigured(ZookeeperNodeListener z) {
    String t = z.getUrlTemplate();
    return t != null && !t.isEmpty() && t.contains("{host}") && t.contains("{port}");
}

When it happens

Trigger: Starting a ZookeeperNodeListener whose urlTemplate field is null or empty — setUrlTemplate(...) was never called or received a blank string.

Common situations: Config key typo (e.g. url-template vs urlTemplate); property omitted in yaml; template missing the {host}/{port} placeholders which a separate validation may also reject downstream.

Related errors

• Please set the ZooKeeper node path.
• ZK Client is NULL, Please set the zkConnectString.
• No Observer(such as PoolUpdater) specified.
• Cannot load remote config file from the
• {className}

AI-assisted analysis of alibaba/druid@fa8dc99126 (2026-08-14). Data as JSON: /api/errors/d0ea69d5fe06dbf3. Report an issue: GitHub.

Appendix: source

Thrown at core/src/main/java/com/alibaba/druid/pool/ha/node/ZookeeperNodeListener.java:185

            List<NodeEvent> events = NodeEvent.getEventsByDiffProperties(getProperties(), properties);
            if (events != null && !events.isEmpty()) {
                setProperties(properties);
            }
            return events;
        } finally {
            lock.unlock();
        }
    }

    private void checkParameters() {
        if (client == null && StringUtils.isEmpty(zkConnectString)) {
            throw new DruidRuntimeException("ZK Client is NULL, Please set the zkConnectString.");
        }
        if (StringUtils.isEmpty(path)) {
            throw new DruidRuntimeException("Please set the ZooKeeper node path.");
        }
        if (StringUtils.isEmpty(urlTemplate)) {
            throw new DruidRuntimeException("Please set the urlTemplate.");
        }
    }

    private void updateSingleNode(PathChildrenCacheEvent event, NodeEventTypeEnum type) {
        ChildData data = event.getData();
        String nodeName = getNodeName(data);
        List<String> names = new ArrayList<String>();
        names.add(getPrefix() + "." + nodeName);
        Properties properties = getPropertiesFromChildData(data);
        List<NodeEvent> events = NodeEvent.generateEvents(properties, names, type);

        if (events.isEmpty()) {
            return;
        }
        if (type == NodeEventTypeEnum.ADD) {
            getProperties().putAll(properties);
        } else {
            for (String n : properties.stringPropertyNames()) {

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