simple geo ip server

cmd/server/main.go

@@ -0,0 +1,68 @@
+package main
+
+import (
+	"log"
+	"os"
+
+	"github.com/gofiber/fiber/v2"
+
+	"geoip-rest/internal/geo"
+)
+
+const (
+	defaultPort   = "8080"
+	defaultDBPath = "/data/GeoLite2-City.mmdb"
+)
+
+func main() {
+	dbPath := env("GEOIP_DB_PATH", defaultDBPath)
+	port := env("PORT", defaultPort)
+
+	resolver, err := geo.NewResolver(dbPath)
+	if err != nil {
+		log.Fatalf("failed to open GeoIP database: %v", err)
+	}
+	defer resolver.Close()
+
+	app := fiber.New(fiber.Config{
+		DisableStartupMessage: true,
+	})
+
+	app.Get("/health", func(c *fiber.Ctx) error {
+		return c.JSON(fiber.Map{"status": "ok"})
+	})
+
+	app.Get("/lookup", func(c *fiber.Ctx) error {
+		ip := c.Query("ip")
+		if ip == "" {
+			ip = c.IP()
+		}
+
+		location, err := resolver.Lookup(ip)
+		if err != nil {
+			if err == geo.ErrInvalidIP {
+				return c.Status(fiber.StatusBadRequest).JSON(fiber.Map{
+					"error": "invalid ip address",
+				})
+			}
+
+			return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{
+				"error": "lookup failed",
+			})
+		}
+
+		return c.JSON(location)
+	})
+
+	log.Printf("starting GeoIP API on :%s using %s", port, dbPath)
+	if err := app.Listen(":" + port); err != nil {
+		log.Fatalf("server stopped: %v", err)
+	}
+}
+
+func env(key, fallback string) string {
+	if val := os.Getenv(key); val != "" {
+		return val
+	}
+	return fallback
+}