@karlorz/dbhub

[!NOTE]
Brought to you by Bytebase, open-source database DevSecOps platform.

DBHub is a universal database gateway implementing the Model Context Protocol (MCP) server interface. This gateway allows MCP-compatible clients to connect to and explore different databases.

 +------------------+    +--------------+    +------------------+
 |                  |    |              |    |                  |
 |                  |    |              |    |                  |
 |  Claude Desktop  +--->+              +--->+    PostgreSQL    |
 |                  |    |              |    |                  |
 |  Cursor          +--->+    DBHub     +--->+    SQL Server    |
 |                  |    |              |    |                  |
 |                  |    |              +--->+    MySQL         |
 |                  |    |              |    |                  |
 |                  |    |              +--->+    MariaDB       |
 |                  |    |              |    |                  |
 +------------------+    +--------------+    +------------------+
      MCP Clients           MCP Server             Databases

Demo HTTP Endpoint

https://demo.dbhub.ai/message connects a sample employee database. You can point Cursor or MCP Inspector to it to see it in action.

Supported Matrix

Database Resources

Resource Name	URI Format	PostgreSQL	MySQL	MariaDB	SQL Server
schemas	db://schemas	✅	✅	✅	✅
tables_in_schema	db://schemas/{schemaName}/tables	✅	✅	✅	✅
table_structure_in_schema	db://schemas/{schemaName}/tables/{tableName}	✅	✅	✅	✅
indexes_in_table	db://schemas/{schemaName}/tables/{tableName}/indexes	✅	✅	✅	✅
procedures_in_schema	db://schemas/{schemaName}/procedures	✅	✅	✅	✅
procedure_details_in_schema	db://schemas/{schemaName}/procedures/{procedureName}	✅	✅	✅	✅

Database Tools

Tool	Command Name	Description	PostgreSQL	MySQL	MariaDB	SQL Server
Execute SQL	execute_sql	Execute single or multiple SQL statements (separated by semicolons)	✅	✅	✅	✅

Prompt Capabilities

Prompt	Command Name	PostgreSQL	MySQL	MariaDB	SQL Server
Generate SQL	generate_sql	✅	✅	✅	✅
Explain DB Elements	explain_db	✅	✅	✅	✅

Installation

Docker

# PostgreSQL example
docker run --rm --init \
   --name dbhub \
   --publish 8080:8080 \
   karlorz/dbhub \
   --transport http \
   --port 8080 \
   --dsn "postgres://user:password@localhost:5432/dbname?sslmode=disable"

NPM

# PostgreSQL example
npx @karlorz/dbhub --transport http --port 8080 --dsn "postgres://user:password@localhost:5432/dbname?sslmode=disable"

Claude Desktop

• Claude Desktop only supports stdio transport https://github.com/orgs/modelcontextprotocol/discussions/16

// claude_desktop_config.json
{
  "mcpServers": {
    "dbhub-postgres-docker": {
      "command": "docker",
      "args": [
        "run",
        "-i",
        "--rm",
        "karlorz/dbhub",
        "--transport",
        "stdio",
        "--dsn",
        // Use host.docker.internal as the host if connecting to the local db
        "postgres://user:[e-mail]:5432/dbname?sslmode=disable"
      ]
    },
    "dbhub-postgres-npx": {
      "command": "npx",
      "args": [
        "-y",
        "@karlorz/dbhub",
        "--transport",
        "stdio",
        "--dsn",
        "postgres://user:password@localhost:5432/dbname?sslmode=disable"
      ]
    },
  }
}

Cursor

• Cursor supports both stdio and http.
• Follow Cursor MCP guide and make sure to use Agent mode.

Usage

SSL Connections

You can specify the SSL mode using the sslmode parameter in your DSN string:

Database	sslmode=disable	sslmode=require	Default SSL Behavior
PostgreSQL	✅	✅	Certificate verification
MySQL	✅	✅	Certificate verification
MariaDB	✅	✅	Certificate verification
SQL Server	✅	✅	Certificate verification

SSL Mode Options:

• sslmode=disable: All SSL/TLS encryption is turned off. Data is transmitted in plaintext.
• sslmode=require: Connection is encrypted, but the server's certificate is not verified. This provides protection against packet sniffing but not against man-in-the-middle attacks. You may use this for trusted self-signed CA.

Without specifying sslmode, most databases default to certificate verification, which provides the highest level of security.

Example usage:

# Disable SSL
postgres://user:password@localhost:5432/dbname?sslmode=disable

# Require SSL without certificate verification
postgres://user:password@localhost:5432/dbname?sslmode=require

# Standard SSL with certificate verification (default)
postgres://user:password@localhost:5432/dbname

Read-only Mode

You can run DBHub in read-only mode, which restricts SQL query execution to read-only operations:

# Enable read-only mode
npx @karlorz/dbhub --readonly --dsn "postgres://user:password@localhost:5432/dbname"

In read-only mode, only readonly SQL operations are allowed.

This provides an additional layer of security when connecting to production databases.

Configure your database connection

[!WARNING] If your user/password contains special characters, you need to escape them first. (e.g. pass#word should be escaped as pass%23word)

For real databases, a Database Source Name (DSN) is required. You can provide this in several ways:

• Command line argument (highest priority):

  npx @karlorz/dbhub  --dsn "postgres://user:password@localhost:5432/dbname?sslmode=disable"
  

• Environment variable (second priority):

  export DSN="postgres://user:password@localhost:5432/dbname?sslmode=disable"
  npx @karlorz/dbhub
  

• Environment file (third priority):

  • For development: Create .env.local with your DSN
  • For production: Create .env with your DSN

  DSN=postgres://user:password@localhost:5432/dbname?sslmode=disable
  

[!WARNING] When running in Docker, use host.docker.internal instead of localhost to connect to databases running on your host machine. For example: mysql://user:[e-mail]:3306/dbname

DBHub supports the following database connection string formats:

Database	DSN Format	Example
MySQL	mysql://[user]:[password]@[host]:[port]/[database]	mysql://user:password@localhost:3306/dbname?sslmode=disable
MariaDB	mariadb://[user]:[password]@[host]:[port]/[database]	mariadb://user:password@localhost:3306/dbname?sslmode=disable
PostgreSQL	postgres://[user]:[password]@[host]:[port]/[database]	postgres://user:password@localhost:5432/dbname?sslmode=disable
SQL Server	sqlserver://[user]:[password]@[host]:[port]/[database]	sqlserver://user:password@localhost:1433/dbname?sslmode=disable

SQL Server

Extra query parameters:

authentication

• authentication=azure-active-directory-access-token. Only applicable when running from Azure. See DefaultAzureCredential.

Transport

• stdio (default) - for direct integration with tools like Claude Desktop:

  npx @karlorz/dbhub --transport stdio --dsn "postgres://user:password@localhost:5432/dbname?sslmode=disable"
  

• http - for browser and network clients:

  npx @karlorz/dbhub --transport http --port 5678 --dsn "postgres://user:password@localhost:5432/dbname?sslmode=disable"
  

Command line options

Option	Environment Variable	Description	Default
dsn	DSN	Database connection string	Required
transport	TRANSPORT	Transport mode: stdio or http	stdio
port	PORT	HTTP server port (only applicable when using --transport=http)	8080
readonly	READONLY	Restrict SQL execution to read-only operations	false

Development

• Install dependencies:

  pnpm install
  

• Run in development mode:

  pnpm dev
  

• Build for production:

  pnpm build
  pnpm start --transport stdio --dsn "postgres://user:password@localhost:5432/dbname?sslmode=disable"
  

Testing

The project uses Vitest for comprehensive unit and integration testing:

• Run all tests: pnpm test
• Run tests in watch mode: pnpm test:watch
• Run integration tests: pnpm test:integration

Integration Tests

DBHub includes comprehensive integration tests for all supported database connectors using Testcontainers. These tests run against real database instances in Docker containers, ensuring full compatibility and feature coverage.

Prerequisites

• Docker: Ensure Docker is installed and running on your machine
• Docker Resources: Allocate sufficient memory (recommended: 4GB+) for multiple database containers
• Network Access: Ability to pull Docker images from registries

Running Integration Tests

Note: This command runs all integration tests in parallel, which may take 5-15 minutes depending on your system resources and network speed.

# Run all database integration tests
pnpm test:integration

# Run only PostgreSQL integration tests
pnpm test src/connectors/__tests__/postgres.integration.test.ts
# Run only MySQL integration tests
pnpm test src/connectors/__tests__/mysql.integration.test.ts
# Run only MariaDB integration tests
pnpm test src/connectors/__tests__/mariadb.integration.test.ts
# Run only SQL Server integration tests
pnpm test src/connectors/__tests__/sqlserver.integration.test.ts
# Run JSON RPC integration tests
pnpm test src/__tests__/json-rpc-integration.test.ts

All integration tests follow these patterns:

• Container Lifecycle: Start database container → Connect → Setup test data → Run tests → Cleanup
• Shared Test Utilities: Common test patterns implemented in IntegrationTestBase class
• Database-Specific Features: Each database includes tests for unique features and capabilities
• Error Handling: Comprehensive testing of connection errors, invalid SQL, and edge cases

Troubleshooting Integration Tests

Container Startup Issues:

# Check Docker is running
docker ps

# Check available memory
docker system df

# Pull images manually if needed
docker pull postgres:15-alpine
docker pull mysql:8.0
docker pull mariadb:10.11
docker pull mcr.microsoft.com/mssql/server:2019-latest

SQL Server Timeout Issues:

• SQL Server containers require significant startup time (3-5 minutes)
• Ensure Docker has sufficient memory allocated (4GB+ recommended)
• Consider running SQL Server tests separately if experiencing timeouts

Network/Resource Issues:

# Run tests with verbose output
pnpm test:integration --reporter=verbose

# Run single database test to isolate issues
pnpm test:integration -- --testNamePattern="PostgreSQL"

# Check Docker container logs if tests fail
docker logs <container_id>

Pre-commit Hooks (for Developers)

The project includes pre-commit hooks to run tests automatically before each commit:

• After cloning the repository, set up the pre-commit hooks:

  ./scripts/setup-husky.sh
  

• This ensures the test suite runs automatically whenever you create a commit, preventing commits that would break tests.

Debug with MCP Inspector

stdio

# PostgreSQL example
TRANSPORT=stdio DSN="postgres://user:password@localhost:5432/dbname?sslmode=disable" npx @modelcontextprotocol/inspector node /path/to/dbhub/dist/index.js

HTTP

# Start DBHub with HTTP transport
pnpm dev --transport=http --port=8080

# Start the MCP Inspector in another terminal
npx @modelcontextprotocol/inspector

Connect to the DBHub server /message endpoint

Contributors

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