fix: add http error responses (#494)

This features adds rfc7807 Problem detail responses when an error happens processing a request.

This will greatly improve the common issues  with "blank pages" and "404 pages" issues which should now properly tell the user what input was wrong (group that does not exist, container name that does not exist, etc.)

internal/server/server.go

@@ -0,0 +1,67 @@
+package server
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"github.com/gin-gonic/gin"
+	"github.com/sablierapp/sablier/app/http/routes"
+	"github.com/sablierapp/sablier/config"
+	"log/slog"
+	"net/http"
+	"time"
+)
+
+func setupRouter(ctx context.Context, logger *slog.Logger, serverConf config.Server, s *routes.ServeStrategy) *gin.Engine {
+	r := gin.New()
+
+	r.Use(StructuredLogger(logger))
+	r.Use(gin.Recovery())
+
+	registerRoutes(ctx, r, serverConf, s)
+
+	return r
+}
+
+func Start(ctx context.Context, logger *slog.Logger, serverConf config.Server, s *routes.ServeStrategy) {
+	start := time.Now()
+
+	if logger.Enabled(ctx, slog.LevelDebug) {
+		gin.SetMode(gin.DebugMode)
+	} else {
+		gin.SetMode(gin.ReleaseMode)
+	}
+
+	r := setupRouter(ctx, logger, serverConf, s)
+
+	var server *http.Server
+	server = &http.Server{
+		Addr:    fmt.Sprintf(":%d", serverConf.Port),
+		Handler: r,
+	}
+
+	logger.Info("starting ",
+		slog.String("listen", server.Addr),
+		slog.Duration("startup", time.Since(start)))
+
+	go StartHttp(server, logger)
+
+	// Graceful web server shutdown.
+	<-ctx.Done()
+	logger.Info("server: shutting down")
+	err := server.Close()
+	if err != nil {
+		logger.Error("server: shutdown failed", slog.Any("error", err))
+	}
+}
+
+// StartHttp starts the Web server in http mode.
+func StartHttp(s *http.Server, logger *slog.Logger) {
+	if err := s.ListenAndServe(); err != nil {
+		if errors.Is(err, http.ErrServerClosed) {
+			logger.Info("server: shutdown complete")
+		} else {
+			logger.Error("server failed to start", slog.Any("error", err))
+		}
+	}
+}