Multi-Database MCP Client

A Model Context Protocol (MCP) server that enables secure interaction with multiple database types including MySQL, MariaDB, TiDB, OceanBase, and AWS RDS/Aurora MySQL. This server exposes database operations as MCP tools and resources while proxying actual SQL execution to a remote HTTP service.

🚀 Features

• Universal SQL Execution: Execute any SQL statement (SELECT, INSERT, UPDATE, DELETE, DDL) through a single tool
• Multi-Database Support: Works with MySQL, MariaDB, TiDB, OceanBase, and compatible cloud databases
• HTTP Proxy Architecture: Decouples MCP interface from database connections via HTTP forwarding
• Schema Introspection: Get table structures and database metadata as MCP resources
• Test Data Generation: Built-in tool for generating development test data
• Flexible Configuration: Support for multiple database instances with runtime switching
• Async I/O: Full asynchronous operation using aiohttp and asyncio
• Structured Logging: Comprehensive logging with loguru to both stderr and rotating files

🏗️ Architecture

The system follows a proxy pattern where the MCP server acts as a client-side interface:

MCP Client → FastMCP Tools/Resources → HTTP POST → Remote DB Server → Database

Key Components

• src/server.py: MCP server with FastMCP framework, tool/resource definitions
• src/utils/db_operate.py: HTTP-proxied SQL execution engine
• src/utils/db_config.py: Singleton configuration loader with multi-instance support
• src/resources/db_resources.py: Database metadata and configuration resource builders
• src/tools/db_tool.py: Test data generation utilities
• src/utils/http_util.py: Async HTTP client helpers
• src/utils/logger_util.py: Logging setup and configuration path resolution

📋 Requirements

• Python 3.12+
• A remote database server accessible via the configured multiDBServer endpoint

🛠️ Installation

1. Install from PyPI (Recommended)

pip install multidb-mcp-client

2. Configure database connection

Edit dbconfig.json with your database credentials:

{
    "dbPoolSize": 5,
    "dbMaxOverflow": 10,
    "dbPoolTimeout": 30,
    "dbType-Comment": "The database currently in use,such as MySQL/MariaDB/TiDB OceanBase/RDS/Aurora MySQL DataBases",
    "dbList": [
        {   "dbInstanceId": "oceanbase_1",
            "dbHost": "localhost",
            "dbPort": 2281,
            "dbDatabase": "oceanbase_db",
            "dbUsername": "root",
            "dbPassword": "123456",
            "dbType": "OceanBase",
            "dbVersion": "V4.0.0",
            "dbActive": true
        },
        {   "dbInstanceId": "mysql_2",
            "dbHost": "localhost",
            "dbPort": 3306,
            "dbDatabase": "mysql_db",
            "dbUsername": "root",
            "dbPassword": "123456",
            "dbType": "MySQL",
            "dbVersion": "8.0",
            "dbActive": false
        },
        {   "dbInstanceId": "tidb_3",
            "dbHost": "localhost",
            "dbPort": 4000,
            "dbDatabase": "tidb_db",
            "dbUsername": "root",
            "dbPassword": "123456",
            "dbType": "TiDB",
            "dbVersion": "8.5.3",
            "dbActive": false
        }
    ],
    "multiDBServer": "http://127.0.0.1:8080/mcp/executeQuery",
    "logPath": "/path/to/logs",
    "logLevel": "INFO"
}

Configuration Properties

• dbList: Array of database instance configurations
  • dbActive: Exactly one instance must be true (the active database)
  • dbType: Supported values include MySQL, OceanBase, TiDB, etc.
• multiDBServer: HTTP endpoint that accepts SQL execution requests
• logPath: Directory for log files (auto-creates if missing)
• logLevel: One of TRACE, DEBUG, INFO, WARNING, ERROR, CRITICAL

3. Configure MCP Client

Add to your MCP client configuration file:

{
  "mcpServers": {
    "multidb-mcp-client": {
      "command": "multidb-mcp-client",
      "env": {
        "config_file": "/path/to/your/dbconfig.json"
      },
      "disabled": false
    }
  }
}

Note: Replace /path/to/your/dbconfig.json with the actual path to your configuration file.

4. Clone the repository (Development Mode)

git clone https://github.com/j00131120/mcp_database_server.git
cd mcp_database_server/multidb_mcp_client
# Import project into your IDE

5. Configure MCP Client for Development

{
  "mcpServers": {
    "multidb-mcp-client": {
      "command": "/bin/uv",
      "args": ["run", "src/server.py"],
      "cwd": "/path/to/your/project",
      "env": {
        "config_file": "/path/to/your/dbconfig.json"
      },
      "disabled": false,
      "autoApprove": ["describe_table", "sql_exec", "generate_demo_data"]
    }
  }
}

# command
uv absolute path
# cwd
project absolute path
# config_file
dbconfig.json file path

🚀 Running the Server

Command Line

After installation, use the provided CLI command:

multidb-mcp-client

This starts the MCP server over stdio for consumption by MCP-compatible clients.

FastMCP CLI (Alternative)

# List available MCP servers
fastmcp servers list

# Run via entry point (defined in pyproject.toml)
fastmcp run mysql

Environment Variables

• config_file: Override default config file path
• Standard logging environment variables supported by loguru

🛠️ MCP Tools

sql_exec(sql: str)

Execute any SQL statement with automatic transaction handling.

Parameters:

• sql (string): SQL statement to execute

Returns:

{
  "success": true,
  "result": [...],  // Query results or affected row count
  "message": "SQL executed successfully"
}

Usage Examples:

# Query data
await sql_exec("SELECT * FROM users WHERE age > 18")

# Insert data
await sql_exec("INSERT INTO users (name, email) VALUES ('Alice', 'alice@example.com')")

# Update records
await sql_exec("UPDATE users SET email = 'newemail@example.com' WHERE id = 1")

# DDL operations
await sql_exec("CREATE TABLE products (id INT PRIMARY KEY, name VARCHAR(100))")

describe_table(table_name: str)

Get detailed table structure information.

Parameters:

• table_name (string): Name of the table (supports database.table format)

Returns: Same format as sql_exec, with result containing column metadata.

Usage Examples:

await describe_table("users")
await describe_table("inventory.products")

generate_demo_data(table_name: str, columns_name: List[str], num: int)

Generate test data for development and testing.

Parameters:

• table_name (string): Target table name
• columns_name (array): List of column names to populate
• num (integer): Number of test records to generate

Usage Examples:

# Generate 100 test users
await generate_demo_data("users", ["name", "email", "phone"], 100)

# Generate 50 test products
await generate_demo_data("products", ["product_name", "category", "description"], 50)

📊 MCP Resources

database://tables

Provides comprehensive metadata for all database tables.

Returns:

{
  "uri": "database://tables",
  "mimeType": "application/json",
  "text": "[{\"name\": \"users\", \"columns\": [...], \"record_count\": 1250}, ...]"
}

Use Cases:

• Schema exploration and documentation
• Database monitoring and statistics
• Query planning and optimization

database://config

Provides current database configuration (with sensitive data masked).

Returns:

{
  "uri": "database://config", 
  "mimeType": "application/json",
  "text": "{\"dbInstanceId\": \"primary_oceanbase\", \"dbHost\": \"localhost\", \"dbPassword\": \"***hidden***\", ...}"
}

📝 Logging

The system provides comprehensive logging:

• Console Output: Logs to stderr for MCP client visibility
• File Logging: Rotating log files (10MB max, 7-day retention)
• Structured Format: Timestamp, level, function, line number, and message
• Configurable Levels: TRACE through CRITICAL

Log files are stored in:

• Configured logPath directory
• Default: <project_root>/logs/mcp_server.log

🔒 Security Considerations

Current Security Features

• Password Masking: Sensitive data hidden in resource responses
• HTTP Client: Supports custom headers for authentication
• Configuration Isolation: Only active database config exposed

Security Recommendations

1. Credential Management: Store database passwords in environment variables or secure vaults
2. Network Security: Use HTTPS for multiDBServer endpoint with proper authentication
3. Access Control: Restrict sql_exec tool usage to trusted environments
4. File Permissions: Secure dbconfig.json with appropriate file system permissions
5. Network Isolation: Deploy multiDBServer in a secured network segment

Production Deployment

# Use environment variables for sensitive data
export DB_PASSWORD="your_secure_password"
export MULTIDB_SERVER_URL="https://secure-db-proxy.internal.com/api/v1/execute"

# Restrict config file permissions
chmod 600 dbconfig.json

# Run with non-root user
useradd -r mcp-client
sudo -u mcp-client multidb-mcp-client

🧪 Development

Project Structure

multidb_mcp_client/
├── src/
│   ├── server.py              # MCP server and tool definitions
│   ├── resources/
│   │   └── db_resources.py    # Resource data builders
│   ├── tools/
│   │   └── db_tool.py         # Tool implementations
│   └── utils/
│       ├── db_config.py       # Configuration management
│       ├── db_operate.py      # SQL execution via HTTP
│       ├── http_util.py       # HTTP client utilities
│       └── logger_util.py     # Logging configuration
├── dbconfig.json              # Database configuration
├── pyproject.toml             # Project metadata and dependencies
└── logs/                      # Log output directory

Code Style

• Explicit naming: Clear, descriptive function and variable names
• Early returns: Reduce nesting with guard clauses
• Type annotations: Public APIs include type hints
• Error handling: Comprehensive exception handling with logging
• Async/await: Proper async patterns throughout

Key Dependencies

• fastmcp: MCP framework and protocol implementation
• aiohttp: Async HTTP client for database proxy calls
• loguru: Structured logging with rotation and formatting
• mcp[cli]: MCP command-line tools

📄 License

MIT License - see the LICENSE file for details.

🔗 Links

• Homepage: https://github.com/j00131120/mcp_database_server/tree/main/multidb_mcp_client
• Documentation: https://github.com/j00131120/mcp_database_server/blob/main/multidb_mcp_client/README.md
• Source Code: https://github.com/j00131120/mcp_database_server.git
• Issue Tracker: https://github.com/j00131120/mcp_database_server/issues
• Changelog: https://github.com/j00131120/mcp_database_server/blob/main/multidb_mcp_client/CHANGELOG.md

🤝 Contributing

1. Fork the repository
2. Create a feature branch: git checkout -b feature/amazing-feature
3. Commit your changes: git commit -m 'Add amazing feature'
4. Push to the branch: git push origin feature/amazing-feature
5. Open a Pull Request

📞 Support

For questions, issues, or contributions:

• Author: Frank Jin (j00131120@163.com)
• GitHub Issues: Use the issue tracker for bug reports and feature requests
• Documentation: Check the repository wiki for additional documentation

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Note: This MCP server requires a compatible remote database service running at the configured multiDBServer endpoint. Ensure your remote service implements the expected HTTP API contract before running the client.