Proxy Advanced Usage

Proxy Advanced Usage

The Swixter proxy gateway supports advanced routing, header injection, and traffic monitoring beyond the basic usage covered in Proxy Gateway commands.

Architecture

┌──────────┐     ┌──────────────┐     ┌──────────────┐
│ AI Coder │ ──▶ │ Swixter Proxy│ ──▶ │ Provider API │
│ (client) │     │ (localhost)  │     │ (remote)     │
└──────────┘     └──────┬───────┘     └──────────────┘
                        │
                   ┌────▼────┐
                   │  Logger │
                   └─────────┘

Configuration

Full proxy configuration in ~/.config/swixter/config.json:

{
  "proxy": {
    "port": 18721,
    "host": "127.0.0.1",
    "autoStart": false,
    "logLevel": "debug",
    "timeout": 30000,
    "maxBodyLogSize": 4096,
    "headers": {
      "X-Custom-Header": "value"
    }
  }
}

Option	Description	Default
port	Listen port (0 = auto-assign)	0
host	Listen address	"127.0.0.1"
autoStart	Start proxy on profile apply	false
logLevel	debug, info, warn, error	"info"
timeout	Request timeout in ms	30000
maxBodyLogSize	Max bytes to log per request/response body	4096
headers	Additional headers to inject	{}

Custom Routing

Route different models to different backends:

{
  "proxy": {
    "routes": [
      {
        "match": { "model": "claude-*" },
        "upstream": "https://api.anthropic.com"
      },
      {
        "match": { "model": "gpt-*" },
        "upstream": "https://api.openai.com/v1"
      }
    ]
  }
}

Each route has:

• match: Criteria to match (model, provider)
• upstream: URL to forward matching requests to

Header Injection

Add custom headers to proxied requests:

{
  "proxy": {
    "headers": {
      "X-Environment": "development",
      "X-Request-Source": "swixter-proxy"
    }
  }
}

Useful for:

• API gateway routing keys
• Usage tracking per environment
• Custom authentication middleware

Logging & Monitoring

Log Levels

# Detailed debug output
swixter proxy start --log-level debug

# Production mode (errors only)
swixter proxy start --log-level error

Log Format

Each request is logged with:

{
  "timestamp": "2026-04-29T10:30:00.000Z",
  "method": "POST",
  "path": "/v1/messages",
  "status": 200,
  "duration_ms": 1234,
  "request_size": 2048,
  "response_size": 512
}

Real-Time Logs

# Tail logs
swixter proxy logs --follow

# Filter by status code
swixter proxy logs --status 4xx

# Last 50 requests
swixter proxy logs --last 50

Performance

The proxy adds minimal overhead (~1-5ms latency):

• Request/response body streaming (no buffering for large payloads)
• Connection pooling for upstream requests
• No TLS termination overhead (plain HTTP on localhost)

Security

• Proxy binds to 127.0.0.1 by default (localhost only)
• No external network access
• Headers are sanitized (Hop-by-hop headers removed)
• Body logging truncation prevents sensitive data leaks in logs