# ClickHouse MCP Server

A Model Context Protocol (MCP) server that provides tools for interacting with ClickHouse databases. Built with [xmcp](https://github.com/basementstudio/xmcp) and supports both HTTP and stdio transport methods.

## Features

- **List Databases**: Retrieve all databases from your ClickHouse server
- **List Tables**: Get tables from a specific database
- **Run Select Queries**: Execute SELECT, SHOW, and DESCRIBE queries safely
- **Multiple Transport Modes**: Supports stdio, HTTP, and SSE (Server-Sent Events)
- **TLS/SSL Support**: Configurable certificate handling for secure connections

## Installation

### From npm (when published)

```bash
npm install -g clickhouse-mcp-server
```

### From source

```bash
git clone https://github.com/ahmedrowaihi/clickhouse-mcp-server.git
cd clickhouse-mcp-server
bun install
bun run build
```

## Usage

### As a CLI tool (after global install)

```bash
# Start in stdio mode (for local/subprocess communication)
clickhouse-mcp stdio

# Start in HTTP mode (for remote/network access)
clickhouse-mcp http

# Start in SSE mode (Server-Sent Events over HTTP)
clickhouse-mcp sse
```

### Development mode

```bash
# Start development server
bun run dev

# Build for production
bun run build

# Run specific modes
bun run start:stdio
bun run start:http
```

### Direct execution (after building)

```bash
# Using the compiled launcher
node dist/launcher.js stdio
node dist/launcher.js http
node dist/launcher.js sse

# Or run server files directly
node dist/stdio.js
node dist/http.js
```

## Configuration

### Environment Variables

Set these environment variables before running the server:

```bash
export CLICKHOUSE_HOST_URL=https://your-clickhouse-server.com:8443
export CLICKHOUSE_USER=your-username
export CLICKHOUSE_PASSWORD=your-password
export CLICKHOUSE_DATABASE=your-database

# Optional settings with defaults
export CLICKHOUSE_SECURE=true
export CLICKHOUSE_VERIFY=true
export CLICKHOUSE_CONNECT_TIMEOUT_SEC=10
export CLICKHOUSE_SEND_RECEIVE_TIMEOUT_SEC=60

# Optional TLS certificate path
export CLICKHOUSE_CERT_PATH=/path/to/certificate.pem
```

Or create a `.env` file in your project root:

```env
# ClickHouse connection settings
CLICKHOUSE_HOST_URL=https://your-clickhouse-server.com:8443
CLICKHOUSE_USER=your-username
CLICKHOUSE_PASSWORD=your-password
CLICKHOUSE_DATABASE=your-database

# Optional settings with defaults
CLICKHOUSE_SECURE=true
CLICKHOUSE_VERIFY=true
CLICKHOUSE_CONNECT_TIMEOUT_SEC=10
CLICKHOUSE_SEND_RECEIVE_TIMEOUT_SEC=60

# Optional TLS certificate path
CLICKHOUSE_CERT_PATH=/path/to/certificate.pem
```

### MCP Client Configuration

#### Claude Desktop

Add this to your Claude Desktop configuration file:

**On macOS**: `~/Library/Application Support/Claude/claude_desktop_config.json`
**On Windows**: `%APPDATA%/Claude/claude_desktop_config.json`

```json
{
  "mcpServers": {
    "clickhouse": {
      "command": "clickhouse-mcp",
      "args": ["stdio"],
      "env": {
        "CLICKHOUSE_HOST_URL": "https://your-clickhouse-server.com:8443",
        "CLICKHOUSE_USER": "your-username",
        "CLICKHOUSE_PASSWORD": "your-password",
        "CLICKHOUSE_DATABASE": "your-database",
        "CLICKHOUSE_SECURE": "true",
        "CLICKHOUSE_VERIFY": "true",
        "CLICKHOUSE_CONNECT_TIMEOUT_SEC": "10",
        "CLICKHOUSE_SEND_RECEIVE_TIMEOUT_SEC": "60"
      }
    }
  }
}
```

#### Using with npx (if not globally installed)

```json
{
  "mcpServers": {
    "clickhouse": {
      "command": "npx",
      "args": ["clickhouse-mcp-server", "stdio"],
      "env": {
        "CLICKHOUSE_HOST_URL": "https://your-clickhouse-server.com:8443",
        "CLICKHOUSE_USER": "your-username",
        "CLICKHOUSE_PASSWORD": "your-password",
        "CLICKHOUSE_DATABASE": "your-database"
      }
    }
  }
}
```

#### HTTP/SSE Mode Setup

For HTTP-based MCP clients, you need to run the server in HTTP or SSE mode and configure your client to connect via URL.

**Step 1: Create .env file**

Create a `.env` file in your project directory:

```env
CLICKHOUSE_HOST_URL=https://sql-clickhouse.clickhouse.com:8443
CLICKHOUSE_USER=demo
CLICKHOUSE_PASSWORD=
CLICKHOUSE_DATABASE=default
CLICKHOUSE_SECURE=true
```

**Step 2: Start the server**

```bash
# Start in HTTP mode
clickhouse-mcp http

# Or start in SSE mode
clickhouse-mcp sse
```

The server will start on `http://localhost:3001` by default and accepts mcp requests on the `/mcp` path.

**Step 3: Configure MCP Client**

For MCP clients that support HTTP connections, add this to your configuration:

```json
{
  "mcpServers": {
    "clickhouse-playground": {
      "url": "http://127.0.0.1:3001/mcp"
    }
  }
}
```

**Complete Example for Playground Testing:**

1. Create `.env` file:

   ```env
   CLICKHOUSE_HOST_URL=https://sql-clickhouse.clickhouse.com:8443
   CLICKHOUSE_USER=demo
   CLICKHOUSE_PASSWORD=
   CLICKHOUSE_DATABASE=default
   CLICKHOUSE_SECURE=true
   ```

2. Start server:

   ```bash
   clickhouse-mcp sse
   ```

3. Configure your MCP client:

   ```json
   {
     "mcpServers": {
       "clickhouse-playground": {
         "url": "http://127.0.0.1:3001/mcp"
       }
     }
   }
   ```

> **Note**: HTTP/SSE mode is ideal for web-based MCP clients, remote access, or when you need multiple clients to connect to the same server instance.

### Quick Start with ClickHouse Playground

To quickly test the MCP server, you can use the public ClickHouse SQL Playground:

#### Environment Variables for Playground

```bash
export CLICKHOUSE_HOST_URL=https://sql-clickhouse.clickhouse.com:8443
export CLICKHOUSE_USER=demo
export CLICKHOUSE_PASSWORD=""
export CLICKHOUSE_DATABASE=default
export CLICKHOUSE_SECURE=true
```

#### Claude Desktop Configuration for Playground

```json
{
  "mcpServers": {
    "clickhouse-playground": {
      "command": "clickhouse-mcp",
      "args": ["stdio"],
      "env": {
        "CLICKHOUSE_HOST_URL": "https://sql-clickhouse.clickhouse.com:8443",
        "CLICKHOUSE_USER": "demo",
        "CLICKHOUSE_PASSWORD": "",
        "CLICKHOUSE_DATABASE": "default",
        "CLICKHOUSE_SECURE": "true"
      }
    }
  }
}
```

#### Test Commands

Once configured, you can test these queries in Claude Desktop:

1. **List databases**: "Show me all available databases"
2. **List tables**: "What tables are in the default database?"
3. **Sample query**: "Show me the first 10 rows from any table"

> **Note**: The ClickHouse Playground is a public demo environment. Don't use it for production data or sensitive information.

### Environment Variables

| Variable                              | Description                    | Required | Default |
| ------------------------------------- | ------------------------------ | -------- | ------- |
| `CLICKHOUSE_HOST_URL`                 | Full URL to ClickHouse server  | Yes      | -       |
| `CLICKHOUSE_USER`                     | Username for authentication    | Yes      | -       |
| `CLICKHOUSE_PASSWORD`                 | Password for authentication    | Yes      | -       |
| `CLICKHOUSE_DATABASE`                 | Default database to connect to | Yes      | -       |
| `CLICKHOUSE_SECURE`                   | Use HTTPS/TLS connection       | No       | `true`  |
| `CLICKHOUSE_VERIFY`                   | Verify SSL certificates        | No       | `true`  |
| `CLICKHOUSE_CONNECT_TIMEOUT_SEC`      | Connection timeout in seconds  | No       | `10`    |
| `CLICKHOUSE_SEND_RECEIVE_TIMEOUT_SEC` | Request timeout in seconds     | No       | `60`    |
| `CLICKHOUSE_CERT_PATH`                | Path to custom SSL certificate | No       | -       |

## Available Tools

### 1. List Databases

Lists all databases available on the ClickHouse server.

**Usage in MCP client:**

```json
{
  "method": "tools/call",
  "params": {
    "name": "list_databases"
  }
}
```

### 2. List Tables

Lists all tables in a specified database.

**Parameters:**

- `database` (string): Name of the database

**Usage in MCP client:**

```json
{
  "method": "tools/call",
  "params": {
    "name": "list_tables",
    "arguments": {
      "database": "my_database"
    }
  }
}
```

### 3. Run Select Query

Executes SELECT, SHOW, or DESCRIBE queries on the ClickHouse database.

**Parameters:**

- `query` (string): The SQL query to execute (must start with SELECT, SHOW, or DESCRIBE)

**Usage in MCP client:**

```json
{
  "method": "tools/call",
  "params": {
    "name": "run_select_query",
    "arguments": {
      "query": "SELECT * FROM my_table LIMIT 10"
    }
  }
}
```

## Transport Modes

### STDIO Mode

Best for local development and subprocess communication:

```bash
clickhouse-mcp stdio
```

### HTTP Mode

Ideal for remote access and web-based clients:

```bash
clickhouse-mcp http
```

### SSE Mode

Server-Sent Events over HTTP for real-time applications:

```bash
clickhouse-mcp sse
```

### Building

```bash
# Build everything (xmcp + launcher)
bun run build

# Build only xmcp components
bun run build:xmcp
```

## Security

- All queries are executed with `readonly: "1"` setting for safety
- Only SELECT, SHOW, and DESCRIBE queries are allowed
- TLS/SSL support for secure connections

## Requirements

- Node.js >= 20.0.0
- ClickHouse server with network access
- Valid ClickHouse credentials

## License

MIT

## Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Add tests if applicable
5. Submit a pull request

## Links

- [GitHub Repository](https://github.com/ahmedrowaihi/clickhouse-mcp-server)