haproxy-mcp/CLAUDE.md

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

HAProxy Dynamic Load Balancer Management Suite - a system for runtime management of HAProxy without restarts. Provides MCP interface for dynamic domain/server management. Frontend supports HTTP/HTTPS/HTTP3, backends use HTTP only (SSL termination at HAProxy).

Key Feature: Zero-reload domain management using HAProxy map files and pool backends.

Architecture

┌──────────────────────────────────────────────────┐
│ HAProxy (host network)                           │
│ TCP 80/443 (HTTP/1.1, HTTP/2) + UDP 443 (HTTP/3) │
│ Runtime API: localhost:9999                      │
│ MCP Proxy: mcp.inouter.com → localhost:8000      │
└──────────────┬───────────────────────────────────┘
               │
         ┌─────▼─────┐
         │ MCP       │
         │ Server    │
         │ :8000     │
         └───────────┘

Domain Routing Flow

Request → HAProxy Frontend
    ↓
domains.map lookup (Host header)
    ↓
pool_N backend (N = 1-100)
    ↓
Server (from servers.json, auto-restored on startup)

Services

HAProxy (Podman Quadlet)

systemctl start haproxy      # Start
systemctl stop haproxy       # Stop
systemctl restart haproxy    # Restart
systemctl status haproxy     # Status

• Quadlet config: /etc/containers/systemd/haproxy.container
• Network mode: host (direct access to host services)

MCP Server (systemd)

systemctl start haproxy-mcp     # Start
systemctl stop haproxy-mcp      # Stop
systemctl restart haproxy-mcp   # Restart
journalctl -u haproxy-mcp -f    # Logs

• Transport: streamable-http
• Internal: http://localhost:8000/mcp
• External: https://mcp.inouter.com/mcp (via HAProxy)
• Auto-restore: Servers restored from servers.json on startup

Zero-Reload Domain Management

How It Works

1. domains.map: Maps domain → pool backend (e.g., example.com pool_1)
2. Pool backends: 100 pre-configured backends (pool_1 to pool_100)
3. Runtime API: Add/remove map entries and configure servers without reload
4. servers.json: Persistent server configuration, auto-restored on MCP startup

Adding a Domain

haproxy_add_domain("example.com", "10.0.0.1")
# Creates: pool_N_1 → 10.0.0.1:80

haproxy_add_domain("api.example.com", "10.0.0.1", 8080)
# Creates: pool_N_1 → 10.0.0.1:8080

This will:

1. Find available pool (e.g., pool_5)
2. Add to domains.map: example.com pool_5
3. Update HAProxy runtime map: add map ... example.com pool_5
4. Configure server in pool via Runtime API (HTTP only)
5. Save to servers.json for persistence

No HAProxy reload required!

Backend Configuration

• Backends always use HTTP (port 80 or custom)
• SSL/TLS termination happens at HAProxy frontend
• Each pool has 10 server slots (pool_N_1 to pool_N_10)

Files

File	Purpose
domains.map	Domain → Pool mapping
servers.json	Server IP/port persistence
haproxy.cfg	Pool backend definitions (static)

SSL/TLS Certificates

Current Setup

Item	Value
ACME Client	acme.sh (Google Trust Services CA)
Cert Directory	/opt/haproxy/certs/ (auto-loaded by HAProxy)
acme.sh Home	~/.acme.sh/

How It Works

1. HAProxy binds with crt /etc/haproxy/certs/ (directory, not file)
2. All .pem files in directory are auto-loaded
3. SNI selects correct certificate based on domain
4. acme.sh deploy hook auto-creates combined PEM on issue/renewal

Adding New Certificate

# Issue certificate (Google Trust Services)
~/.acme.sh/acme.sh --issue \
  --dns dns_cf \
  -d "newdomain.com" -d "*.newdomain.com" \
  --reloadcmd "cat ~/.acme.sh/newdomain.com_ecc/fullchain.cer ~/.acme.sh/newdomain.com_ecc/newdomain.com.key > /opt/haproxy/certs/newdomain.com.pem && podman exec haproxy kill -USR2 1"

Certificate Commands

# List certificates
~/.acme.sh/acme.sh --list

# Renew all
~/.acme.sh/acme.sh --cron

# Force renew specific domain
~/.acme.sh/acme.sh --renew -d "domain.com" --force

# Check loaded certs in HAProxy
ls -la /opt/haproxy/certs/

Cloudflare Credentials

• File: ~/.secrets/cloudflare.ini
• Format: dns_cloudflare_api_token = TOKEN
• Also export: export CF_Token="your_token"

HTTP/3 (QUIC)

Frontend supports all protocols:

TCP 443: HTTP/1.1, HTTP/2
UDP 443: HTTP/3 (QUIC)

Clients receive alt-svc: h3=":443"; ma=86400 header for HTTP/3 upgrade.

MCP Security

HAProxy proxies MCP with Bearer Token authentication (configured in frontend ACL).

Access Rules

Source	Token Required
Tailscale (100.64.0.0/10)	No
External (CF Worker, etc.)	Yes

Token Location

• File: /opt/haproxy/conf/mcp-token.env

Connection Examples

Tailscale (no auth):

claude mcp add --transport http haproxy http://100.108.39.107:8000/mcp

External (with auth):

curl -X POST https://mcp.inouter.com/mcp \
  -H "Authorization: Bearer <token>" \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -d '{"jsonrpc":"2.0","method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"test","version":"1.0"}},"id":0}'

MCP Tools (17 total)

Domain Management

Tool	Description
haproxy_list_domains	List all domains with pool mappings and servers
haproxy_add_domain	Add domain to available pool (no reload)
haproxy_remove_domain	Remove domain from pool (no reload)

Server Management

Tool	Description
haproxy_list_servers	List servers for a domain
haproxy_add_server	Add server to slot (1-10), auto-saved
haproxy_remove_server	Remove server from slot, auto-saved
haproxy_set_server_state	Set state: ready/drain/maint
haproxy_set_server_weight	Set weight (0-256)
haproxy_get_server_health	Get UP/DOWN/MAINT status

Monitoring

Tool	Description
haproxy_stats	HAProxy statistics
haproxy_backends	List backends
haproxy_list_frontends	List frontends with status
haproxy_get_connections	Active connections per server

Configuration

Tool	Description
haproxy_reload	Validate and reload config
haproxy_check_config	Validate config syntax
haproxy_save_state	Save server state to disk (legacy)
haproxy_restore_state	Restore state from disk (legacy)

Key Conventions

Pool-Based Routing

• Domains map to pools: example.com → pool_N
• 100 pools available: pool_1 to pool_100
• Each pool has 10 server slots

Server Naming

Pool backends use simple naming: pool_N_1 to pool_N_10

Examples:

example.com → pool_5
  └─ pool_5_1 (slot 1)
  └─ pool_5_2 (slot 2)
  └─ ... up to pool_5_10

api.example.com → pool_6
  └─ pool_6_1 (slot 1)

Persistence

• domains.map: Survives HAProxy restart
• servers.json: Auto-restored by MCP on startup
• No manual save required - haproxy_add_server auto-saves

HAProxy Runtime API

# Show domain mappings
echo "show map /usr/local/etc/haproxy/domains.map" | nc localhost 9999

# Add domain mapping (runtime only)
echo "add map /usr/local/etc/haproxy/domains.map example.com pool_5" | nc localhost 9999

# Show server state
echo "show servers state" | nc localhost 9999

# Show backends
echo "show backend" | nc localhost 9999

# Set server address
echo "set server pool_1/pool_1_1 addr 10.0.0.1 port 80" | nc localhost 9999

# Enable server
echo "set server pool_1/pool_1_1 state ready" | nc localhost 9999

Directory Structure

/opt/haproxy/
├── mcp/                 # MCP server (streamable-http)
│   └── server.py        # Main MCP server (~1100 lines, 17 tools)
├── conf/
│   ├── haproxy.cfg      # Main HAProxy config (100 pool backends)
│   ├── domains.map      # Domain → Pool mapping
│   ├── servers.json     # Server persistence (auto-managed)
│   └── mcp-token.env    # Bearer token for MCP auth
├── certs/               # SSL/TLS certificates (HAProxy PEM format)
├── data/                # Legacy state files
├── scripts/             # Utility scripts
└── run/                 # Runtime socket files

~/.acme.sh/
├── *_ecc/               # Certificate directories (one per domain)
└── acme.sh              # ACME client script

/etc/containers/systemd/
└── haproxy.container    # Podman Quadlet config

Configuration Files

File	Purpose
/opt/haproxy/conf/haproxy.cfg	HAProxy main config
/opt/haproxy/conf/domains.map	Domain routing map
/opt/haproxy/conf/servers.json	Server persistence
/opt/haproxy/certs/*.pem	SSL certificates (auto-loaded)
/etc/containers/systemd/haproxy.container	Podman Quadlet
/etc/systemd/system/haproxy-mcp.service	MCP service
/opt/haproxy/conf/mcp-token.env	MCP auth token
~/.acme.sh/	acme.sh certificates and config
~/.secrets/cloudflare.ini	Cloudflare API token

Startup Sequence

1. systemd starts haproxy.service
   ↓
2. HAProxy loads haproxy.cfg (100 pool backends)
   ↓
3. HAProxy loads domains.map (domain → pool mapping)
   ↓
4. systemd starts haproxy-mcp.service
   ↓
5. MCP server reads servers.json
   ↓
6. MCP server restores servers via Runtime API
   ↓
7. Ready to serve traffic