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go.missing_graceful_shutdown

Stability High

Detects HTTP servers that don’t handle SIGTERM for graceful shutdown, causing dropped requests during deployments.

Why It Matters

Without graceful shutdown:

Dropped requests — In-flight requests are terminated mid-processing
Data loss — Partial writes, uncommitted transactions
Connection errors — Clients receive connection reset errors
Deployment failures — Rolling updates cause user-visible errors

Example

// ❌ Before (no graceful shutdown)
func main() {
    http.ListenAndServe(":8080", handler)
}

// ✅ After (graceful shutdown)
func main() {
    server := &http.Server{
        Addr:    ":8080",
        Handler: handler,
    }

    // Start server in goroutine
    go func() {
        if err := server.ListenAndServe(); err != http.ErrServerClosed {
            log.Fatal(err)
        }
    }()

    // Wait for interrupt signal
    quit := make(chan os.Signal, 1)
    signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)
    <-quit

    // Graceful shutdown with timeout
    ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
    defer cancel()

    if err := server.Shutdown(ctx); err != nil {
        log.Fatal("Server forced to shutdown:", err)
    }
    log.Println("Server exited gracefully")
}

What Unfault Detects

http.ListenAndServe() without signal handling
Missing server.Shutdown() calls
log.Fatal() in signal handlers (prevents cleanup)
Hardcoded exits without cleanup

Auto-Fix

Unfault generates patches that add signal handling and graceful shutdown:

import (
    "context"
    "os"
    "os/signal"
    "syscall"
)

// Graceful shutdown setup
quit := make(chan os.Signal, 1)
signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)

Kubernetes Configuration

spec:
  terminationGracePeriodSeconds: 30
  containers:
    - name: app
      lifecycle:
        preStop:
          exec:
            command: ["/bin/sh", "-c", "sleep 5"]