ClickHouse Install & Auth Skill

ClickHouse Install & Auth

Overview

Set up the official ClickHouse client for Node.js or Python and configure authentication to ClickHouse Cloud or a self-hosted instance.

Prerequisites

Node.js 18+ or Python 3.8+
A running ClickHouse instance (Cloud or self-hosted)
Connection credentials (host, port, user, password)

Instructions

Step 1: Install the Official Client

# Node.js — official client (HTTP-based, supports streaming)
npm install @clickhouse/client

# Python — official client
pip install clickhouse-connect

Step 2: Configure Environment Variables

# .env (NEVER commit — add to .gitignore)
CLICKHOUSE_HOST=https://abc123.us-east-1.aws.clickhouse.cloud:8443
CLICKHOUSE_USER=default
CLICKHOUSE_PASSWORD=your-password-here

# Self-hosted (HTTP interface on port 8123, native on 9000)
# CLICKHOUSE_HOST=http://localhost:8123

Step 3: Create the Client (Node.js)

import { createClient } from '@clickhouse/client';

// ClickHouse Cloud
const client = createClient({
  url: process.env.CLICKHOUSE_HOST,           // https://<host>:8443
  username: process.env.CLICKHOUSE_USER,       // default
  password: process.env.CLICKHOUSE_PASSWORD,
  // ClickHouse Cloud requires TLS — the client handles it via https:// URL
});

// Self-hosted (no TLS)
const localClient = createClient({
  url: 'http://localhost:8123',
  username: 'default',
  password: '',
});

Step 4: Verify Connection

async function verifyConnection() {
  // Ping returns true if the server is reachable
  const alive = await client.ping();
  console.log('ClickHouse ping:', alive.success);  // true

  // Run a test query
  const rs = await client.query({
    query: 'SELECT version() AS ver, uptime() AS uptime_sec',
    format: 'JSONEachRow',
  });
  const rows = await rs.json<{ ver: string; uptime_sec: number }>();
  console.log('Server version:', rows[0].ver);
  console.log('Uptime (sec):', rows[0].uptime_sec);
}

verifyConnection().catch(console.error);

Step 5: Python Alternative

import clickhouse_connect

client = clickhouse_connect.get_client(
    host='abc123.us-east-1.aws.clickhouse.cloud',
    port=8443,
    username='default',
    password='your-password-here',
    secure=True,
)

result = client.query('SELECT version(), uptime()')
print(f"Version: {result.result_rows[0][0]}")

Connection Options Reference

| Option | Default | Description | |--------|---------|-------------| | url | http://localhost:8123 | Full URL including protocol and port | | username | default | ClickHouse user | | password | '' | User password | | database | default | Default database for queries | | request_timeout | 30000 | Query timeout in ms | | compression.request | false | Compress request bodies (gzip) | | compression.response | true | Decompress responses | | max_open_connections | 10 | HTTP keep-alive pool size | | clickhouse_settings | {} | Server-side settings per session |

ClickHouse Cloud vs Self-Hosted

| Feature | Cloud | Self-Hosted | |---------|-------|-------------| | Port | 8443 (HTTPS) | 8123 (HTTP) / 8443 (HTTPS) | | TLS | Required | Optional | | Engine | SharedMergeTree | MergeTree family | | Auth | User/password, Cloud API keys | User/password, LDAP, Kerberos |

Error Handling

| Error | Cause | Solution | |-------|-------|----------| | ECONNREFUSED | Server not running | Check host/port, verify ClickHouse is up | | Authentication failed | Wrong user/password | Verify credentials in ClickHouse users.xml or Cloud console | | CERTIFICATE_VERIFY_FAILED | TLS mismatch | Use https:// for Cloud, check CA certs for self-hosted | | TIMEOUT | Network/firewall | Check IP allowlists in Cloud console, firewall rules | | Database not found | Wrong database name | Run SHOW DATABASES to list available databases |

Resources

Next Steps

Proceed to clickhouse-hello-world for your first table and query.

Agent Skills: ClickHouse Install & Auth

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