hermes-skills/skills/devops/infrastructure-automation/references/mcp-mysql-setup.md

MySQL MCP Server Setup

Deployed Jul 7, 2026 on Core. Connects Hermes to MariaDB on wphost02.

Architecture

Hermes → MCP mysql_query → Python stdio MCP server → autossh tunnel → wphost02:3306

Components

1. Persistent SSH Tunnel (autossh)

/etc/systemd/system/mysql-tunnel.service — connects 127.0.0.1:33060 → wphost02:3306

2. MCP Server

/root/.hermes/scripts/mcp-mysql.py — reads env vars, speaks JSON-RPC 2.0 over stdio. Single tool: mysql_query(sql) which returns JSON.

3. Database Connection Issues (MariaDB 11.1)

• SSL disabled: MariaDB doesn't support SSL. Use --skip-ssl or ssl_disabled=True
• Collation: Must set charset="utf8mb4" and collation="utf8mb4_general_ci" — MariaDB doesn't support utf8mb4_0900_ai_ci
• Initial attempt: npm MCP servers fail with MySQL/MariaDB due to protocol/handshake quirks. Custom Python server was necessary.

4. Config

Stored in ~/.hermes/config.yaml under mcp.mysql. Enabled by default.