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MCP PostgreSQL Server (Stateful and Dual Transport)

A Model Context Protocol (MCP) server that provides both HTTP and Stdio transports for interacting with PostgreSQL databases. This server exposes database resources and tools through both transport methods, allowing for flexible integration in different environments.

Features

  • Dual Transport Support: Both HTTP (StreamableHTTPServerTransport) and Stdio (StdioServerTransport)
  • Database Resources: List tables and retrieve schema information
  • Query Tool: Execute read-only SQL queries
  • Stateful Sessions: HTTP transport supports session management
  • Docker Support: Containerized deployments for both transports
  • Production Ready: Graceful shutdown, error handling, and logging

Project Structure

postgres-mcp-server
├── Dockerfile                    # Main Docker container configuration for the MCP server
├── Makefile                      # Build automation and common development tasks
├── README.md                     # Project documentation and setup instructions
├── docker-compose.yml            # Production Docker Compose configuration
├── package.json                  # Node.js project configuration and dependencies
├── pyproject.toml               # Python project configuration
├── tsconfig.json                # TypeScript compiler configuration
└── src/
    ├── config/
    │   ├── database.ts          # Database connection configuration and setup
    │   └── env.ts               # Environment variable handling and validation
    ├── http/
    │   ├── Dockerfile           # Docker configuration specific to HTTP server mode
    │   ├── app.ts               # HTTP application setup and Express.js configuration
    │   └── httpHandler.ts       # HTTP request handlers for MCP protocol over HTTP
    ├── index.ts                 # Main entry point for the MCP server
    ├── resources/
    │   ├── databaseSchema.ts    # MCP resource for exposing database schema information
    │   ├── databaseTables.ts    # MCP resource for listing and describing database tables
    │   └── helloWorld.ts        # Example/test resource implementation
    ├── server/
    │   └── server.ts            # Core MCP server implementation and protocol handling
    ├── stdio/
    │   ├── Dockerfile           # Docker configuration for stdio communication mode
    │   └── stdioServer.ts       # MCP server configured for stdio communication
    ├── stdioIndex.ts            # Entry point for stdio-based MCP server
    └── tools/
        └── queryTool.ts         # MCP tool for executing PostgreSQL queries

Quick Start

1. Environment Setup

Copy environment template

cp .env.example .env

Edit your database credentials

nano .env

2. Development

Download node.js and npm from here

# Install dependencies
npm install

# Build the project
npm run build

Run HTTP server in development

npm run dev:http

Run Stdio server in development

npm run dev:stdio

3. Production

Build and start HTTP server

npm run build
npm run start:http

Or start Stdio server

npm run build
npm run start:stdio

Podman Usage

  1. Install podman from here
  2. Install uv from here
  3. Install podman compose package: uv add podman-compose (or uv sync to sync packages in pyproject.toml)
#get the environment variables
set -a
source .env
set +a
podman machine start
make podman-up

Test using MCP Inspector

Install MCP Inspector: instructions: here

Check Stdio MCP Server

cd postgres-mcp-server/ #path to project directory
#from project directory
npx @modelcontextprotocol/inspector npx tsx src/stdioIndex.ts

Stdio in MCP Inspector

Check Streamable HTTP MCP Server

  1. Install podman from here
  2. Install uv from here
  3. Install podman compose package: uv sync (will sync packages in pyproject.toml)
#get the environment variables
set -a
source .env
set +a
#start podman container (if running for the first time)
make podman-up #will construct the container of the MCP server
#if already exists: podman start <name_of_the_container>
npx @modelcontextprotocol/inspector

After selecting Streamable HTTP from drop down menu, insert http://localhost:3000/mcp into URL.

MCP tools: MCP Tools in MCP Inspector

MCP Resource: MCP Resource in MCP Inspector

Configuration

Environment Variables

You have to specify these inside the .env file.

Variable Description Default Required
POSTGRES_USERNAME PostgreSQL username - Yes
POSTGRES_PASSWORD PostgreSQL password - Yes
POSTGRES_HOST PostgreSQL host - Yes
POSTGRES_DATABASE PostgreSQL database name - Yes
PORT HTTP server port 3000 No
HOST HTTP server host 0.0.0.0 No
CORS_ORIGIN Allowed CORS origins (comma-separated) localhost:8080,localhost:3000 No
NODE_ENV Environment mode development No

Resources

Hello World (hello://world)

A simple greeting message for testing.

Database Tables (database://tables)

Lists all tables in the public schema with their schema URIs.

Database Schema (database://tables/{tableName}/schema)

Returns column information for a specific table.

Tools

query

Execute read-only SQL queries against the database.

Parameters:

  • sql (string): The SQL query to execute

Transport Differences

Feature HTTP Transport Stdio Transport
Session Management ✅ Stateful sessions ❌ Stateless
Concurrent Connections ✅ Multiple clients ❌ Single process
Web Integration ✅ REST API compatible ❌ CLI only
Interactive Use ✅ Via HTTP clients ✅ Direct stdio
Docker Deployment ✅ Web service ✅ CLI container

Health Checks

The HTTP server includes a basic health check endpoint accessible at the /health endpoint with a GET request (returns 405 Method Not Allowed, confirming the server is responsive).

Troubleshooting

Common Issues

  1. Database Connection Errors

    # Check your database credentials in .env
    # Ensure PostgreSQL is running and accessible
  2. Port Already in Use

    # Change PORT in .env or stop conflicting services
    lsof -i :3000
  3. Docker Build Issues

    # Clean Docker cache
    npm run docker:clean
    docker system prune -a
  4. Session Management (HTTP)

    # Sessions are stored in memory and will reset on server restart
    # For production, consider implementing persistent session storage

Development

Adding New Resources

  1. Create a new file in src/resources/
  2. Implement the resource registration function
  3. Add it to src/server/server.ts

Adding New Tools

  1. Create a new file in src/tools/
  2. Implement the tool registration function
  3. Add it to src/server/server.ts

License

MIT

Contributing

Please read the contributing guidelines and submit pull requests to the main repository.

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MCP (Model Context Protocol) Server for postgres Database

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