Multi-Database MCP Server

Multi-Database MCP Server

A plugin-based MCP server that enables interaction with multiple databases (MySQL, PostgreSQL, MongoDB, SQL Server, Redis) through a unified interface with configurable read/write permissions and independent plugin architecture.

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README

@nam088/mcp-server

A professional MCP (Model Context Protocol) server implementation with a plugin-based architecture.

Features

  • Plugin-Based Architecture: Modular design with independent plugins
  • Workspace Structure: Each plugin is a separate npm package with its own dependencies
  • Dynamic Loading: Load plugins from configuration or environment variables
  • Type-Safe: Full TypeScript support
  • Extensible: Easy to create custom plugins

Architecture

This project uses a monorepo workspace structure where:

  • Core System (@nam088/mcp-core): Plugin interfaces and registry
  • Plugins (e.g., @nam088/mcp-redis): Independent packages with their own dependencies
  • Main Server: Loads and orchestrates plugins

See ARCHITECTURE.md for detailed architecture documentation.

Installation

npm install

Building

# Build all packages
npm run build

# Clean build artifacts
npm run clean

Usage

Install the packages you need in your project:

npm install @nam088/mcp-core @nam088/mcp-mysql @nam088/mcp-sql-server @nam088/mcp-mongodb @nam088/mcp-postgres @nam088/mcp-redis

Create your MCP server:

import { Server } from '@modelcontextprotocol/sdk/server/index.js';
import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';
import { PluginRegistry } from '@nam088/mcp-core';
import { MysqlPlugin } from '@nam088/mcp-mysql';
import { SqlServerPlugin } from '@nam088/mcp-sql-server';
import { MongoDBPlugin } from '@nam088/mcp-mongodb';
import { PostgresPlugin } from '@nam088/mcp-postgres';
import { RedisPlugin } from '@nam088/mcp-redis';

const server = new Server(
  { name: 'my-mcp-server', version: '1.0.0' },
  { capabilities: { tools: {} } }
);

const registry = new PluginRegistry(server);

// Register plugins with connection strings (recommended)
await registry.registerPlugin(MongoDBPlugin, {
  uri: process.env.MONGODB_URI || 'mongodb://localhost:27017',
  mode: 'READONLY',
});

await registry.registerPlugin(PostgresPlugin, {
  url: process.env.POSTGRES_URL || 'postgresql://postgres:password@localhost:5432/mydb',
  mode: 'READONLY',
});

await registry.registerPlugin(RedisPlugin, {
  url: process.env.REDIS_URL || 'redis://localhost:6379',
});

// MySQL (using individual config - connection string not yet supported)
await registry.registerPlugin(MysqlPlugin, {
  host: process.env.MYSQL_HOST || 'localhost',
  port: parseInt(process.env.MYSQL_PORT || '3306'),
  user: process.env.MYSQL_USER || 'root',
  password: process.env.MYSQL_PASSWORD,
  database: process.env.MYSQL_DATABASE,
  mode: 'READONLY',
});

// SQL Server (using individual config)
await registry.registerPlugin(SqlServerPlugin, {
  server: process.env.MSSQL_HOST || 'localhost',
  port: parseInt(process.env.MSSQL_PORT || '1433'),
  user: process.env.MSSQL_USER || 'sa',
  password: process.env.MSSQL_PASSWORD,
  database: process.env.MSSQL_DATABASE,
  mode: 'READONLY',
});

// Start server
const transport = new StdioServerTransport();
await server.connect(transport);

Configuration Examples

MCP Server Configuration (for Cursor/Claude Desktop)

Add to your ~/.cursor/mcp.json or Claude Desktop config:

{
  "mcpServers": {
    "mongodb": {
      "command": "npx",
      "args": ["-y", "@nam088/mcp-mongodb"],
      "env": {
        "MONGODB_URI": "mongodb://admin:admin@localhost:27017/db_name?authMechanism=SCRAM-SHA-256",
        "MONGODB_DATABASE": "mydb",
        "MONGODB_MODE": "READONLY"
      }
    },
    "postgres": {
      "command": "npx",
      "args": ["-y", "@nam088/mcp-postgres"],
      "env": {
        "POSTGRES_URL": "postgresql://postgres:password@localhost:5432/mydb",
        "POSTGRES_MODE": "READONLY"
      }
    },
    "redis": {
      "command": "npx",
      "args": ["-y", "@nam088/mcp-redis"],
      "env": {
        "REDIS_URL": "redis://localhost:6379"
      }
    },
    "mysql": {
      "command": "npx",
      "args": ["-y", "@nam088/mcp-mysql"],
      "env": {
        "MYSQL_HOST": "localhost",
        "MYSQL_PORT": "3306",
        "MYSQL_USER": "root",
        "MYSQL_PASSWORD": "your_password",
        "MYSQL_DATABASE": "mydb",
        "MYSQL_MODE": "READONLY"
      }
    },
    "sql-server": {
      "command": "npx",
      "args": ["-y", "@nam088/mcp-sql-server"],
      "env": {
        "MSSQL_HOST": "localhost",
        "MSSQL_PORT": "1433",
        "MSSQL_USER": "sa",
        "MSSQL_PASSWORD": "your_password",
        "MSSQL_DATABASE": "mydb",
        "MSSQL_MODE": "READONLY"
      }
    }
  }
}

Plugin Configuration (for Dynamic Loading)

Create a plugins.config.json file for dynamic plugin loading:

[
  {
    "package": "@nam088/mcp-mongodb",
    "export": "MongoDBPlugin",
    "enabled": true,
    "config": {
      "uri": "mongodb://admin:admin@localhost:27017/db_name",
      "mode": "READONLY"
    }
  },
  {
    "package": "@nam088/mcp-postgres",
    "export": "PostgresPlugin",
    "enabled": true,
    "config": {
      "url": "postgresql://postgres:password@localhost:5432/mydb",
      "mode": "READONLY"
    }
  },
  {
    "package": "@nam088/mcp-redis",
    "export": "RedisPlugin",
    "enabled": true,
    "config": {
      "url": "redis://localhost:6379"
    }
  },
  {
    "package": "@nam088/mcp-mysql",
    "export": "MysqlPlugin",
    "enabled": true,
    "config": {
      "host": "localhost",
      "port": 3306,
      "user": "root",
      "password": "your_password",
      "database": "mydb",
      "mode": "READONLY"
    }
  },
  {
    "package": "@nam088/mcp-sql-server",
    "export": "SqlServerPlugin",
    "enabled": true,
    "config": {
      "server": "localhost",
      "port": 1433,
      "user": "sa",
      "password": "your_password",
      "database": "mydb",
      "mode": "READONLY"
    }
  }
]

Available Plugins

MySQL Plugin (@nam088/mcp-mysql)

Comprehensive MySQL/MariaDB plugin with 20+ tools.

Tools:

  • mysql_query - Execute SELECT queries with parameters
  • mysql_execute - Execute INSERT/UPDATE/DELETE/DDL (WRITEONLY or FULL mode)
  • mysql_list_databases - List all databases
  • mysql_list_tables - List tables in database
  • mysql_describe_table - Get table structure
  • mysql_list_indexes - List table indexes
  • mysql_list_constraints - List table constraints
  • mysql_explain_query - Query execution plan
  • mysql_processlist - View running queries
  • mysql_kill_query - Kill running query (WRITEONLY or FULL mode)
  • mysql_optimize_table - Optimize tables (WRITEONLY or FULL mode)
  • mysql_analyze_table - Analyze tables (WRITEONLY or FULL mode)
  • mysql_list_views - List views
  • mysql_list_procedures - List stored procedures
  • mysql_list_functions - List stored functions
  • mysql_list_triggers - List triggers
  • And more...

Dependencies: mysql2
Modes: READONLY, WRITEONLY, FULL
See: packages/mysql/README.md

SQL Server Plugin (@nam088/mcp-sql-server)

Microsoft SQL Server plugin with comprehensive tools.

Tools:

  • sqlserver_query - Execute SELECT queries
  • sqlserver_execute - Execute INSERT/UPDATE/DELETE/DDL (FULL mode)
  • sqlserver_list_databases - List all databases
  • sqlserver_list_tables - List tables in schema
  • sqlserver_describe_table - Get table structure
  • sqlserver_list_schemas - List all schemas
  • sqlserver_list_indexes - List table indexes
  • sqlserver_list_constraints - List table constraints
  • sqlserver_explain_query - Query execution plan
  • sqlserver_active_sessions - View active sessions
  • sqlserver_kill_session - Kill session (FULL mode)
  • sqlserver_rebuild_index - Rebuild indexes (FULL mode)
  • sqlserver_update_statistics - Update statistics (FULL mode)
  • And more...

Dependencies: mssql
Modes: READONLY, FULL
See: packages/sql-server/README.md

MongoDB Plugin (@nam088/mcp-mongodb)

MongoDB plugin with CRUD and aggregation support.

Tools:

  • mongodb_find - Find documents with filtering, sorting, projection
  • mongodb_count - Count documents
  • mongodb_aggregate - Run aggregation pipeline
  • mongodb_insert_one - Insert single document (FULL mode)
  • mongodb_insert_many - Insert multiple documents (FULL mode)
  • mongodb_update_one - Update single document (FULL mode)
  • mongodb_update_many - Update multiple documents (FULL mode)
  • mongodb_delete_one - Delete single document (FULL mode)
  • mongodb_delete_many - Delete multiple documents (FULL mode)
  • mongodb_list_databases - List all databases
  • mongodb_list_collections - List collections in database
  • mongodb_collection_stats - Get collection statistics
  • mongodb_list_indexes - List collection indexes
  • mongodb_create_index - Create index (FULL mode)
  • mongodb_drop_index - Drop index (FULL mode)
  • And more...

Dependencies: mongodb
Modes: READONLY, FULL
See: packages/mongodb/README.md

Redis Plugin (@nam088/mcp-redis)

Redis plugin with support for all data types.

Tools:

  • redis_get - Get value by key
  • redis_set - Set value with optional TTL
  • redis_del - Delete key
  • redis_keys - Find keys by pattern
  • redis_info - Get server information
  • And more... (hash, list, set, sorted set operations)

Dependencies: redis
See: packages/redis/README.md

PostgreSQL Plugin (@nam088/mcp-postgres)

PostgreSQL plugin with comprehensive SQL support.

Tools:

  • postgres_query - Execute SELECT queries
  • postgres_execute - Execute INSERT/UPDATE/DELETE/DDL (FULL mode)
  • postgres_list_tables - List all tables in schema
  • postgres_describe_table - Get table structure
  • postgres_list_schemas - List all schemas
  • postgres_list_indexes - List table indexes
  • postgres_database_info - Get database information

Dependencies: pg
See: packages/postgres/README.md

Creating Custom Plugins

1. Create Plugin Package

mkdir -p packages/mydb/src
cd packages/mydb
npm init -y

2. Setup package.json

{
  "name": "@nam088/mcp-mydb",
  "version": "0.1.0",
  "type": "module",
  "main": "./dist/index.js",
  "types": "./dist/index.d.ts",
  "scripts": {
    "build": "tsc",
    "clean": "rm -rf dist",
    "type-check": "tsc --noEmit"
  },
  "peerDependencies": {
    "@modelcontextprotocol/sdk": "^1.21.1",
    "@nam088/mcp-core": "^0.1.0"
  },
  "dependencies": {
    "mydb-client": "^1.0.0"
  },
  "devDependencies": {
    "@types/node": "^22.10.2",
    "typescript": "^5.7.2"
  }
}

3. Create tsconfig.json

{
  "extends": "../../tsconfig.json",
  "compilerOptions": {
    "outDir": "./dist",
    "rootDir": "./src"
  },
  "include": ["src/**/*"]
}

4. Implement Plugin

// packages/mydb/src/index.ts
import { PluginBase, PluginConfig, PluginContext } from '@nam088/mcp-core';
import { z } from 'zod';

export class MyDBPlugin extends PluginBase {
  readonly metadata: PluginConfig = {
    name: 'mydb',
    version: '0.1.0',
    description: 'MyDB plugin for MCP',
  };

  async initialize(context: PluginContext): Promise<void> {
    await super.initialize(context);
    // Initialize your DB connection
  }

  register(context: PluginContext): void {
    const { server } = context;
    
    server.registerTool('mydb_query', {
      description: 'Query MyDB',
      inputSchema: {
        query: z.string().describe('SQL query'),
      }
    }, async ({ query }) => {
      // Implement your tool
      return {
        content: [{ type: 'text', text: 'Result' }]
      };
    });
  }

  async cleanup(): Promise<void> {
    await super.cleanup();
    // Cleanup resources
  }
}

5. Build and Use

# Build your plugin
cd packages/mydb
npm run build

# Use it in your server
npm install @nam088/mcp-mydb

Development

# Build all packages
npm run build

# Type checking
npm run type-check

# Linting
npm run lint
npm run lint:fix

# Formatting
npm run format
npm run format:check

# Clean build artifacts
npm run clean

Project Structure

mcp-server/
├── packages/
│   ├── core/                    # @nam088/mcp-core
│   │   ├── src/
│   │   ├── package.json
│   │   └── tsconfig.json
│   ├── mysql/                   # @nam088/mcp-mysql
│   │   ├── src/
│   │   ├── bin/
│   │   ├── package.json
│   │   └── tsconfig.json
│   ├── sql-server/              # @nam088/mcp-sql-server
│   │   ├── src/
│   │   ├── bin/
│   │   ├── package.json
│   │   └── tsconfig.json
│   ├── mongodb/                 # @nam088/mcp-mongodb
│   │   ├── src/
│   │   ├── bin/
│   │   ├── package.json
│   │   └── tsconfig.json
│   ├── redis/                   # @nam088/mcp-redis
│   │   ├── src/
│   │   ├── bin/
│   │   ├── package.json
│   │   └── tsconfig.json
│   └── postgres/                # @nam088/mcp-postgres
│       ├── src/
│       ├── bin/
│       ├── package.json
│       └── tsconfig.json
├── package.json                # Root package with workspaces
├── tsconfig.json               # Shared TypeScript config
├── ARCHITECTURE.md             # Architecture documentation
└── QUICK_START.md              # Vietnamese quick start guide

Benefits of This Architecture

  1. Plugin Independence: Each plugin has its own dependencies
    • MySQL: mysql2
    • SQL Server: mssql
    • MongoDB: mongodb
    • Redis: redis
    • PostgreSQL: pg
  2. Selective Installation: Install only the plugins you need
  3. No Dependency Conflicts: Plugins don't interfere with each other
  4. Easy Publishing: Each plugin can be published to npm independently
  5. Flexible Loading: Choose static imports or dynamic loading
  6. Type Safety: Full TypeScript support across all packages
  7. Mode Control: READONLY, WRITEONLY (MySQL), or FULL modes for security
  8. Standalone Servers: Each plugin can run as a standalone MCP server

License

MIT

Author

nam088

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