Minimal gin application

main.go

package main

import (
	"context"
	"log"
	"net/http"
	"os"
	"os/signal"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/joho/godotenv"
)

func main() {
	if err := godotenv.Load(); err != nil {
		log.Println("Warning: .env file not loading. " + err.Error())
	}

	engine := gin.Default()
	engine.GET("/ping", func(c *gin.Context) {
		c.JSON(200, gin.H{
			"message": "pong",
		})
	})

	if port := os.Getenv("PORT"); port != "" {
		srv := http.Server{
			Addr:    ":" + port,
			Handler: engine,
		}

		go func() {
			if err := srv.ListenAndServe(); err != nil {
				log.Printf("ListenAndServe failed, err:" + err.Error())
			}
		}()

		quit := make(chan os.Signal)
		signal.Notify(quit, os.Interrupt, os.Kill)
		<-quit

		log.Printf("Shutdown server ...")

		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancel()

		if err := srv.Shutdown(ctx); err != nil {
			log.Fatalf("Server shutdown failed, err:" + err.Error())
		}

		log.Printf("Server exiting")
		return
	}

	if sockFile := os.Getenv("SOCK_FILE"); sockFile != "" {
		if err := engine.RunUnix(sockFile); err != nil {
			log.Panicf("Cannot start a server, err:" + err.Error())
		}
	}

	log.Panic("Cannot start a server, undefined PORT or SOCK_FILE environment")
}