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netwatch/backend/README.md
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clawbot f3895789d2
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feat(backend): server hardening: timeouts, security headers, trusted-proxy client IP (closes #19)
Add ReadHeaderTimeout and IdleTimeout to the http.Server as named constants beside the existing timeouts. Add a SecurityHeaders middleware (HSTS, a JSON-API CSP of default-src 'none'; frame-ancestors 'none', X-Frame-Options DENY, nosniff, Referrer-Policy, Permissions-Policy), registered before CORS so preflight responses carry it. Resolve the client IP from X-Forwarded-For / X-Real-IP only when the direct peer is in the trusted-proxy allowlist (loopback plus RFC1918 by default, configurable via TRUSTED_PROXIES); an untrusted peer's forwarded headers are ignored. Uses net/netip; no new dependency.

Model: opus-4-8 (implementation and review); claude-fable-5 (merge)
2026-09-21 15:05:25 +02:00

3.1 KiB

netwatch-server is an MIT-licensed Go HTTP backend by @sneak that receives telemetry reports from the NetWatch SPA and persists them as zstd-compressed JSONL files on disk.

Getting Started

# Build and run locally
make run

# Run tests, lint, and format check
make check

# Docker
docker build -t netwatch-server .
docker run -p 8080:8080 netwatch-server

Rationale

The NetWatch frontend collects latency measurements from the browser but has no way to persist or aggregate them. This backend provides a minimal POST /api/v1/reports endpoint that buffers incoming reports in memory and flushes them to compressed files on disk for later analysis.

Design

The server is structured as an fx-wired Go application under cmd/netwatch-server/. Internal packages in internal/ follow standard Go project layout:

  • config: Loads configuration from environment variables and config files via Viper.
  • handlers: HTTP request handlers for the API (health check, report ingestion).
  • reportbuf: In-memory buffer that accumulates JSONL report lines and flushes to zstd-compressed files when the buffer reaches 10 MiB or every 60 seconds.
  • server: Chi-based HTTP server with middleware wiring and route registration.
  • healthcheck, middleware, logger, globals: Supporting infrastructure.

Configuration

Variable Default Description
PORT 8080 HTTP listen port
DATA_DIR ./data/reports Directory for compressed reports
DEBUG false Enable debug logging
TRUSTED_PROXIES loopback + RFC1918 Comma-separated CIDRs whose X-Forwarded-For / X-Real-IP headers are trusted for client IP resolution

TRUSTED_PROXIES defaults to 127.0.0.1/32,::1/128,10.0.0.0/8,172.16.0.0/12,192.168.0.0/16. The loopback entries cover the reverse proxy that shares the container; the RFC1918 ranges match nginx.conf. A request whose direct peer is outside this set has its forwarded headers ignored, and the direct peer is logged instead.

Report storage

Reports are written as reports-<timestamp>.jsonl.zst files in DATA_DIR. Each file contains one JSON object per line, compressed with zstd. Files are created with O_EXCL to prevent overwrites.

TODO

  • Add integration test that POSTs a report and verifies the compressed output
  • Add report decompression/query endpoint
  • Add metrics (Prometheus) for buffer size, flush count, report count
  • Add retention policy to prune old report files

License

MIT. See LICENSE.

Author

@sneak