zai-proxy

Production-grade LLM reverse proxy with token counting, adaptive rate limiting, and a real-time metrics dashboard.

What it is

zai-proxy sits in front of the Z.AI Claude API and adds the observability and reliability layer that bare API access lacks:

• Token tracking — counts input and output tokens on every request, using API-reported usage when available and tiktoken estimation as a fallback
• Adaptive rate limiting — tracks upstream 429 responses with an EWMA ceiling estimator and automatically holds just below the limit, probing periodically to detect ceiling increases
• Prometheus metrics — request counts, latency histograms, token rates, error rates, and rate-limit wait times, all labelled by model and deployment variant
• Blue/green and canary support — tag requests by DEPLOYMENT_VARIANT to compare proxy versions or model configurations side-by-side in the same metrics namespace
• SSE streaming — passes through chunked streaming responses without buffering

Components

proxy/

Go HTTP reverse proxy. Listens on :8080, forwards to the upstream LLM API, and exports Prometheus metrics at /metrics.

See proxy/README.md for full configuration and deployment instructions.

dashboard/

Go backend + React frontend for live monitoring. Scrapes the proxy's Prometheus endpoint every 5 seconds, stores dual-resolution snapshots in SQLite, and streams updates to the browser via SSE.

proxy :8080/metrics  →  Collector  →  SQLite  →  SSE Hub  →  React UI
                                       metrics_5s (24h)
                                       metrics_1m (7d)

Features: request throughput, latency percentiles, token usage totals, error rates, and per-variant comparison panels.

Quick start

# 1. Configure the upstream API key and (optionally) override the target URL
export ZAI_API_KEY="your-api-key"
export ZAI_TARGET_URL="https://your-llm-provider.example.com/v1"  # optional

# 2. Start the proxy
cd proxy
go run .

# Proxy → :8080   Metrics → :8080/metrics

# 3. (Optional) start the dashboard in another terminal
cd dashboard
go run .
# Dashboard → :8080

Environment variables

Proxy

Variable	Default	Description
ZAI_API_KEY	(required)	API key forwarded to the upstream provider
ZAI_TARGET_URL	https://api.z.ai/api/anthropic	Override the upstream base URL
TOKEN_COUNTING_ENABLED	true	Enable/disable token counting
TOKENIZER_MODEL	glm-4	Tokenizer model name for estimation
MAX_WORKERS	10	Max concurrent upstream requests
DEPLOYMENT_VARIANT	production	Label for blue/green or canary tracking
RATE_LIMIT_INITIAL	10.0	Initial rate (req/s)
RATE_LIMIT_MIN	1.0	Minimum rate floor
RATE_LIMIT_MAX	50.0	Maximum rate ceiling
RATE_LIMIT_CEILING_ALPHA	0.3	EWMA smoothing factor for ceiling estimation
RATE_LIMIT_HOLD_MARGIN	0.02	Hold margin below ceiling (as fraction, e.g., 0.02 = 2%)
RATE_LIMIT_PROBE_INTERVAL	10	Probe ceiling every N clean windows
MAX_RETRIES	3	Retry count on transient errors

Dashboard

See docs/notes/ for dashboard configuration and deployment.

Metrics

The proxy exposes standard Prometheus metrics at /metrics:

• zai_proxy_requests_total — request counts by method, path, status, and variant
• zai_proxy_request_duration_seconds — latency histogram
• zai_proxy_request_size_bytes — request size histogram
• zai_proxy_response_size_bytes — response size histogram
• zai_proxy_concurrent_requests — concurrent request gauge
• zai_proxy_upstream_errors_total — upstream error counts by type and variant
• zai_proxy_tokens_total — token counters with labels: direction (input/output/cache_read/cache_write), model, variant, pricing_tier
• zai_proxy_rate_limit_requests_per_second — current rate limit gauge
• zai_proxy_rate_limit_wait_seconds — time spent waiting on the rate limiter
• zai_proxy_rate_limit_adjustments_total — rate limit adjustments by direction and variant
• zai_proxy_rate_limit_rejections_total — requests rejected due to rate limiting
• zai_proxy_retry_attempts_total — retry attempts by reason and variant
• zai_proxy_worker_utilization_ratio — worker utilization gauge
• zai_proxy_max_workers — maximum concurrent workers gauge
• zai_proxy_token_rate_seconds — token processing time histogram
• zai_proxy_token_rate — token throughput histogram (tokens per second)
• zai_proxy_token_count_duration_seconds — token counting operation duration
• zai_proxy_build_info — build information (version, variant, commit, build time)

Docs

• docs/plan/ — architecture decisions and roadmaps
• docs/notes/ — deployment, operations, monitoring, canary procedures
• docs/research/ — tokenizer research, metrics references
• DEVELOPMENT.md — contributor guide
• CONTRIBUTING.md — contribution guidelines

License

See LICENSE if present, or contact the maintainer.