From 924d4b7177449241b3b732735ba0e9639c42c070 Mon Sep 17 00:00:00 2001 From: sneak Date: Mon, 21 Sep 2026 12:49:59 +0000 Subject: [PATCH] fix(server): shut down through fx so buffered reports flush (closes #22) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The server ran os.Exit at the end of its own goroutine, racing fx's teardown and sometimes killing the process before reportbuf's OnStop flushed — silently losing a full flush window of telemetry on every restart, at exit 0. Shutdown now goes through fx.Shutdowner, so every OnStop runs in order. The http.Server is built synchronously in OnStart before the serving goroutine, so shutdown can no longer race or nil-deref it. A listen failure exits non-zero via fx.ExitCode(1). reportbuf's OnStop is guarded by sync.Once. writeTimeout now exceeds the chi per-request budget so that budget is reachable. Dead startupTime, exitCode, and cancelFunc fields are gone. A new test asserts a buffered report reaches disk after the lifecycle stops. Model: opus-4-8 --- TODO.md | 9 ++ backend/internal/reportbuf/reportbuf.go | 20 ++-- backend/internal/reportbuf/reportbuf_test.go | 74 ++++++++++++- backend/internal/server/http.go | 41 +++++-- backend/internal/server/server.go | 110 ++++++------------- 5 files changed, 154 insertions(+), 100 deletions(-) diff --git a/TODO.md b/TODO.md index b284278..ee9f313 100644 --- a/TODO.md +++ b/TODO.md @@ -22,6 +22,15 @@ files, so merging it also closes most compliance gaps. # Completed Steps +- 2026-09-21: shutdown lifecycle correctness. The process now shuts down through + fx instead of `os.Exit`, so every component's `OnStop` runs and buffered + reports are flushed to disk on `SIGTERM` — previously a full flush window of + telemetry was silently lost on every restart. The `http.Server` is now built + before its serving goroutine starts, so shutdown can no longer race or + nil-deref it; a listen failure exits non-zero via `fx.Shutdowner`; `reportbuf` + `OnStop` is idempotent; and `writeTimeout` now exceeds the chi per-request + budget so that budget is actually reachable. Dead `startupTime`, `exitCode`, + and `cancelFunc` fields were removed - 2026-09-21: backend HTTP hardening (issue #19): added `ReadHeaderTimeout` and `IdleTimeout` to the server, a `SecurityHeaders` middleware (HSTS, tight CSP, frame/sniff/referrer/permissions headers) registered before CORS, and diff --git a/backend/internal/reportbuf/reportbuf.go b/backend/internal/reportbuf/reportbuf.go index ff4cbad..1ef3b19 100644 --- a/backend/internal/reportbuf/reportbuf.go +++ b/backend/internal/reportbuf/reportbuf.go @@ -40,11 +40,12 @@ type Params struct { // Buffer accumulates JSON lines in memory and flushes them // to zstd-compressed files on disk. type Buffer struct { - buf bytes.Buffer - dataDir string - done chan struct{} - log *slog.Logger - mu sync.Mutex + buf bytes.Buffer + dataDir string + done chan struct{} + log *slog.Logger + mu sync.Mutex + stopOnce sync.Once } // New creates a Buffer and registers lifecycle hooks to @@ -76,8 +77,13 @@ func New( return nil }, OnStop: func(_ context.Context) error { - close(b.done) - b.flushLocked() + // stopOnce makes OnStop idempotent: a second + // invocation must not close an already-closed channel + // (which would panic) or flush again. + b.stopOnce.Do(func() { + close(b.done) + b.flushLocked() + }) return nil }, diff --git a/backend/internal/reportbuf/reportbuf_test.go b/backend/internal/reportbuf/reportbuf_test.go index 24a9ae9..4b6b550 100644 --- a/backend/internal/reportbuf/reportbuf_test.go +++ b/backend/internal/reportbuf/reportbuf_test.go @@ -1,13 +1,77 @@ package reportbuf_test import ( + "os" + "strings" "testing" - _ "sneak.berlin/go/netwatch/internal/reportbuf" + "sneak.berlin/go/netwatch/internal/config" + "sneak.berlin/go/netwatch/internal/globals" + "sneak.berlin/go/netwatch/internal/logger" + "sneak.berlin/go/netwatch/internal/reportbuf" + + "go.uber.org/fx" + "go.uber.org/fx/fxtest" ) -func TestImport(t *testing.T) { - t.Parallel() - // Compilation check — verifies the package parses - // and all imports resolve. +// TestFlushOnShutdown proves the flush-on-shutdown path: a +// report appended after start but before the periodic flush +// window must reach disk when the fx lifecycle stops. This is +// the exact case that silent data loss on restart used to +// destroy. +func TestFlushOnShutdown(t *testing.T) { + dir := t.TempDir() + t.Setenv("DATA_DIR", dir) + + var buf *reportbuf.Buffer + + app := fxtest.New(t, + fx.Provide( + globals.New, + logger.New, + config.New, + reportbuf.New, + ), + fx.Populate(&buf), + ) + + app.RequireStart() + + err := buf.Append(map[string]string{"probe": "shutdown"}) + if err != nil { + t.Fatalf("append report: %v", err) + } + + // RequireStop runs the reportbuf OnStop hook, which is the + // only code path that flushes buffered reports on shutdown. + app.RequireStop() + + if !hasReportFile(t, dir) { + t.Fatal("no report file on disk after shutdown; " + + "the buffered report was lost") + } +} + +func hasReportFile(t *testing.T, dir string) bool { + t.Helper() + + entries, err := os.ReadDir(dir) + if err != nil { + t.Fatalf("read data dir: %v", err) + } + + for _, e := range entries { + if strings.HasSuffix(e.Name(), ".jsonl.zst") { + info, statErr := e.Info() + if statErr != nil { + t.Fatalf("stat %s: %v", e.Name(), statErr) + } + + if info.Size() > 0 { + return true + } + } + } + + return false } diff --git a/backend/internal/server/http.go b/backend/internal/server/http.go index a0d3c68..e621ce7 100644 --- a/backend/internal/server/http.go +++ b/backend/internal/server/http.go @@ -5,20 +5,31 @@ import ( "fmt" "net/http" "time" + + "go.uber.org/fx" ) const ( readTimeout = 10 * time.Second readHeaderTimeout = 5 * time.Second - writeTimeout = 10 * time.Second idleTimeout = 60 * time.Second maxHeaderBytes = 1 << 20 // 1 MiB + + // requestTimeout (routes.go) is the single per-request + // processing budget, enforced by chi's middleware.Timeout. + // writeTimeout must exceed that budget so a handler can write + // its 503 when the chi timeout fires; if it were shorter the + // server would abort the write first and the chi budget would + // be unreachable dead configuration. + writeTimeout = requestTimeout + 5*time.Second ) -func (s *Server) serveUntilShutdown() { +// newHTTPServer constructs the http.Server. It performs no I/O +// and does not start listening. +func (s *Server) newHTTPServer() *http.Server { listenAddr := fmt.Sprintf(":%d", s.params.Config.Port) - s.httpServer = &http.Server{ + return &http.Server{ Addr: listenAddr, Handler: s, MaxHeaderBytes: maxHeaderBytes, @@ -27,21 +38,29 @@ func (s *Server) serveUntilShutdown() { WriteTimeout: writeTimeout, IdleTimeout: idleTimeout, } +} - s.SetupRoutes() - +// listenAndServe runs the listener until the server is shut +// down. A genuine listen failure (not the expected +// ErrServerClosed from a clean shutdown) requests process +// shutdown through fx with a non-zero exit code, so the failure +// is visible to any supervisor. +func (s *Server) listenAndServe() { s.log.Info("http begin listen", - "listenaddr", listenAddr, + "listenaddr", s.httpServer.Addr, "version", s.params.Globals.Version, "buildarch", s.params.Globals.Buildarch, ) err := s.httpServer.ListenAndServe() - if err != nil && !errors.Is(err, http.ErrServerClosed) { - s.log.Error("listen error", "error", err) + if err == nil || errors.Is(err, http.ErrServerClosed) { + return + } - if s.cancelFunc != nil { - s.cancelFunc() - } + s.log.Error("listen error", "error", err) + + shutdownErr := s.shutdowner.Shutdown(fx.ExitCode(1)) + if shutdownErr != nil { + s.log.Error("request shutdown failed", "error", shutdownErr) } } diff --git a/backend/internal/server/server.go b/backend/internal/server/server.go index a67bd1e..d14dd25 100644 --- a/backend/internal/server/server.go +++ b/backend/internal/server/server.go @@ -1,16 +1,14 @@ // Package server provides the HTTP server lifecycle, -// including startup, routing, signal handling, and graceful -// shutdown. +// including startup, routing, and graceful shutdown. The +// process lifetime is owned by fx: shutdown is requested +// through fx.Shutdowner so every component's OnStop hook runs +// in dependency order. package server import ( "context" "log/slog" "net/http" - "os" - "os/signal" - "syscall" - "time" "sneak.berlin/go/netwatch/internal/config" "sneak.berlin/go/netwatch/internal/globals" @@ -31,19 +29,18 @@ type Params struct { Handlers *handlers.Handlers Logger *logger.Logger Middleware *middleware.Middleware + Shutdowner fx.Shutdowner } // Server is the top-level HTTP server orchestrator. type Server struct { - cancelFunc context.CancelFunc - exitCode int - h *handlers.Handlers - httpServer *http.Server - log *slog.Logger - mw *middleware.Middleware - params Params - router *chi.Mux - startupTime time.Time + h *handlers.Handlers + httpServer *http.Server + log *slog.Logger + mw *middleware.Middleware + params Params + router *chi.Mux + shutdowner fx.Shutdowner } // New creates a Server and registers lifecycle hooks for @@ -57,23 +54,25 @@ func New( s.mw = params.Middleware s.h = params.Handlers s.log = params.Logger.Get() + s.shutdowner = params.Shutdowner lc.Append(fx.Hook{ OnStart: func(_ context.Context) error { - s.startupTime = time.Now().UTC() + // Build the router and http.Server synchronously + // here, before spawning the serving goroutine, so + // httpServer is fully constructed by the time OnStop + // (or an early signal) can read it. fx guarantees + // OnStart returns before OnStop runs, so no + // synchronization or nil check is needed at shutdown. + s.SetupRoutes() + s.httpServer = s.newHTTPServer() - go func() { //nolint:contextcheck // fx OnStart ctx is startup-only; run() creates its own - s.run() - }() + go s.listenAndServe() return nil }, - OnStop: func(_ context.Context) error { - if s.cancelFunc != nil { - s.cancelFunc() - } - - return nil + OnStop: func(ctx context.Context) error { + return s.shutdown(ctx) }, }) @@ -88,60 +87,17 @@ func (s *Server) ServeHTTP( s.router.ServeHTTP(w, r) } -func (s *Server) run() { - exitCode := s.serve() - os.Exit(exitCode) -} - -func (s *Server) serve() int { - var ctx context.Context //nolint:wsl // ctx must be declared before multi-assign - - ctx, s.cancelFunc = context.WithCancel( - context.Background(), - ) - - go func() { - c := make(chan os.Signal, 1) - - signal.Ignore(syscall.SIGPIPE) - signal.Notify(c, os.Interrupt, syscall.SIGTERM) - - sig := <-c - s.log.Info("signal received", "signal", sig) - - if s.cancelFunc != nil { - s.cancelFunc() - } - }() - - go func() { - s.serveUntilShutdown() - }() - - <-ctx.Done() - s.cleanShutdown() - - return s.exitCode -} - -const shutdownTimeout = 5 * time.Second - -func (s *Server) cleanShutdown() { - s.exitCode = 0 - - ctxShutdown, shutdownCancel := context.WithTimeout( - context.Background(), - shutdownTimeout, - ) - defer shutdownCancel() - - err := s.httpServer.Shutdown(ctxShutdown) +// shutdown gracefully stops the HTTP server within the +// deadline of the context fx provides for OnStop. +func (s *Server) shutdown(ctx context.Context) error { + err := s.httpServer.Shutdown(ctx) if err != nil { - s.log.Error( - "server clean shutdown failed", - "error", err, - ) + s.log.Error("server clean shutdown failed", "error", err) + + return err } s.log.Info("server stopped") + + return nil } -- 2.54.0