Aleksey Shakhmatov
f609b12c2f
Document RateLimit's RemoteAddr-by-default keying and WithTrustedProxies, and that WithMaxResponseBody returns ErrResponseTooLarge rather than truncating.
57 lines
3.4 KiB
Markdown
57 lines
3.4 KiB
Markdown
# CLAUDE.md — httpx
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## Commands
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```bash
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go build ./... # compile
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go test ./... # all tests
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go test -race ./... # tests with race detector
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go test -v -run TestName ./package/ # single test
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go vet ./... # static analysis
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```
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## Architecture
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- **Module**: `git.codelab.vc/pkg/httpx`, Go 1.24, zero external dependencies
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### Client
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- **Core pattern**: middleware is `func(http.RoundTripper) http.RoundTripper`
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- **Chain assembly order** (client.go): Logging → User MW → Retry → CB → Balancer → Transport
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- Retry wraps CB+Balancer so each attempt can hit a different endpoint
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- **Circuit breaker** is per-host (`sync.Map` of host → Breaker)
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- **Sentinel errors**: canonical values live in sub-packages, root package re-exports as aliases
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- **balancer.Transport** returns `(Middleware, *Closer)` — Closer must be tracked for health checker shutdown
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- **Client.Close()** stops the health checker goroutine
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- **Client.Patch()** — PATCH method, same pattern as Put/Post
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- **NewFormRequest** — form-encoded request builder (`application/x-www-form-urlencoded`) with `GetBody` for retry
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- **WithMaxResponseBody** — caps `resp.Body` reads; returns `ErrResponseTooLarge` (not silent truncation) when exceeded
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- **middleware.RequestID()** — propagates request ID from context to outgoing `X-Request-Id` header
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- **`internal/requestid`** — shared context key used by both `server` and `middleware` packages to avoid circular imports
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### Server (`server/`)
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- **Core pattern**: middleware is `func(http.Handler) http.Handler`
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- **Server** wraps `http.Server` with `net.Listener`, graceful shutdown via signal handling, lifecycle hooks
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- **Router** wraps `http.ServeMux` — supports groups with prefix + middleware inheritance, `Mount` for sub-handlers, `WithNotFoundHandler` for custom 404
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- **Middleware chain** via `Chain(A, B, C)` — A outermost, C innermost (same as client side)
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- **statusWriter** wraps `http.ResponseWriter` to capture status; implements `Unwrap()` for `http.ResponseController`
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- **Defaults()** preset: RequestID → Recovery → Logging + production timeouts
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- **HealthHandler** exposes `GET /healthz` (liveness) and `GET /readyz` (readiness with pluggable checkers)
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- **CORS** middleware — preflight OPTIONS handling, `AllowOrigins`, `AllowMethods`, `AllowHeaders`, `ExposeHeaders`, `AllowCredentials`, `MaxAge`
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- **RateLimit** middleware — per-key token bucket (`sync.Map`), keys on `RemoteAddr` by default; `X-Forwarded-For` is honored only via `WithTrustedProxies`; `WithRate`/`WithBurst`/`WithKeyFunc`/`WithMaxKeys`, uses `internal/clock`, idle buckets evicted to bound memory
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- **MaxBodySize** middleware — wraps `r.Body` via `http.MaxBytesReader`
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- **Timeout** middleware — wraps `http.TimeoutHandler`, returns 503
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- **WriteJSON** / **WriteError** — JSON response helpers in `server/respond.go`
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## Conventions
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- Functional options for all configuration (client and server)
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- Test helpers: `mockTransport(fn)` wrapping `middleware.RoundTripperFunc` (client), `httptest.NewRecorder`/`httptest.NewRequest` (server)
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- Server tests use `waitForAddr(t, srv)` helper to poll until server is ready
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- No external test frameworks — stdlib only
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- Thread safety required (`sync.Mutex`/`atomic`)
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- `internal/clock` for deterministic time testing
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## See also
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- `AGENTS.md` — universal AI agent guide with common tasks, gotchas, and ASCII diagrams
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