Initial bootrap of application

- Creates scaffold for router and server
- Main program set up for environment, OS signal listener
- Makefile generic commands

cmd/api/main.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"context"
+	"log"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"github.com/davidlick/supermarket-api/internal/http"
+	"github.com/sirupsen/logrus"
+)
+
+var (
+	cfg    config
+	logger *logrus.Logger
+	err    error
+)
+
+func init() {
+	cfg, err = load()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	ll, err := logrus.ParseLevel(cfg.LogLevel)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	logger = logrus.New()
+	logger.SetLevel(ll)
+}
+
+func main() {
+	server := http.NewServer(cfg.APIPort, logger, cfg.Env)
+
+	// Allow app to listen for OS Interrupts and SIGTERMS.
+	serverErrors := make(chan error, 1)
+	osSignals := make(chan os.Signal, 1)
+	signal.Notify(osSignals, os.Interrupt, syscall.SIGTERM)
+
+	go func() {
+		serverErrors <- server.Run()
+	}()
+
+	// Handling for server errors and OS signals.
+	select {
+	case err := <-serverErrors:
+		log.Fatal("error starting server: %w", err.Error())
+	case <-osSignals:
+		log.Println("starting server shutdown...")
+		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+
+		err := server.Shutdown(ctx)
+		if err != nil {
+			log.Fatalf("error shutting down http server: %v", err.Error())
+		}
+	}
+}