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07. Tailscale Networking & Security

Overview​

We rely on Tailscale to create a flat, secure mesh network. This allows valid devices (developers' laptops, AI agent runners) to access the services without exposing public ports.

Concepts​

  • Tailnet: Your private network.
  • ACLs (Access Control Lists): Rules defining who can talk to whom.
  • MagicDNS: Automatic hostname resolution (e.g., http://rag-mcp-node).

Configuration Strategy​

1. Installation​

In cloud-init, we installed Tailscale and advertised the machine as an exit node (optional) but primarily purely as a node.

2. Interface binding​

The Docker services bind to 0.0.0.0 inside the container.

Current Implementation (docker-compose.yml): We use a Tailscale Sidecar to handle authentication and networking, ensuring the RAG service is not exposed constantly to the public internet.

3. Tailscale Sidecar (Implemented)​

To strictly restrict access to the MCP server, we run a ts-serve sidecar (named ts-proxy).

  # 3. Tailscale Sidecar (Auth Proxy)
  ts-proxy:
    image: tailscale/tailscale:latest
    hostname: rag-internal
    restart: always
    environment:
      - TS_AUTHKEY=${TS_AUTHKEY_PROXY}
      - TS_STATE_DIR=/var/lib/tailscale
      - TS_DEST_IP=rag-service
    volumes:
      - ts-state:/var/lib/tailscale
    cap_add:
      - NET_ADMIN
      - NET_RAW
    networks:
      - internal-net

The Application Service (rag-service) binds only to localhost:

    ports:
      - "127.0.0.1:8082:8080"

JSON ACLs (Tailscale Console)​

Enforce that only "devs" tag can reach the "prod" tag.

{
  "groups": {
    "group:admins": ["alice@email.com"],
    "group:bots": ["tag:ai-agent"]
  },
  "acls": [
    {
      "action": "accept",
      "src": ["group:admins"],
      "dst": ["*:*"]
    },
    {
      "action": "accept",
      "src": ["group:bots"],
      "dst": ["tag:prod:8080"] // Only MCP port
    }
  ]
}

Connecting the AI Agent​

To let a local AI agent (like Cursor/Windsurf) use the remote tool:

  1. Ensure laptop is on Tailscale.
  2. Config MCP tool URL: http://rag-mcp-node:8080/sse (or http://rag-internal:8080 if using MagicDNS). The secure tunnel is transparent.