devops: deployment setup and docs

cmd/server/main.go

@@ -1,15 +1,23 @@
 package main
 
 import (
+	"context"
 	"fmt"
 	"log/slog"
 	"net/http"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
 
 	"git.juancwu.dev/juancwu/budgit/internal/app"
 	"git.juancwu.dev/juancwu/budgit/internal/config"
 	"git.juancwu.dev/juancwu/budgit/internal/routes"
 )
 
+// version is set at build time via -ldflags.
+var version = "dev"
+
 func main() {
 	cfg := config.Load()
 
@@ -26,10 +34,40 @@ func main() {
 	}()
 
 	handler := routes.SetupRoutes(a)
-	slog.Info("server starting", "host", cfg.Host, "port", cfg.Port, "env", cfg.AppEnv, "url", fmt.Sprintf("http://%s:%s", cfg.Host, cfg.Port))
 
-	err = http.ListenAndServe(":"+cfg.Port, handler)
-	if err != nil {
+	// Health check bypasses all middleware
+	finalHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method == http.MethodGet && r.URL.Path == "/healthz" {
+			if err := a.DB.Ping(); err != nil {
+				w.WriteHeader(http.StatusServiceUnavailable)
+				w.Write([]byte("db: unreachable"))
+				return
+			}
+			w.WriteHeader(http.StatusOK)
+			w.Write([]byte("ok" + " - version: " + version))
+			return
+		}
+		handler.ServeHTTP(w, r)
+	})
+
+	srv := &http.Server{
+		Addr:    ":" + cfg.Port,
+		Handler: finalHandler,
+	}
+
+	go func() {
+		sigCh := make(chan os.Signal, 1)
+		signal.Notify(sigCh, syscall.SIGTERM, syscall.SIGINT)
+		<-sigCh
+		slog.Info("shutting down gracefully")
+		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+		defer cancel()
+		srv.Shutdown(ctx)
+	}()
+
+	slog.Info("server starting", "version", version, "host", cfg.Host, "port", cfg.Port, "env", cfg.AppEnv, "url", fmt.Sprintf("http://%s:%s", cfg.Host, cfg.Port))
+
+	if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
 		slog.Error("server failed", "error", err)
 		panic(err)
 	}