Configs from environment variables

config/config.go

@@ -0,0 +1,19 @@
+package config
+
+import (
+	"log"
+
+	"github.com/caarlos0/env"
+)
+
+type Config struct {
+	Port string `env:"PORT" envDefault:"3000"`
+}
+
+func Get() (cfg Config) {
+	err := env.Parse(&cfg)
+	if err != nil {
+		log.Fatal(err)
+	}
+	return
+}

main.go

@@ -5,6 +5,7 @@ import (
 	"net/http"
 
 	"github.com/gorilla/mux"
+	"github.com/robertoduessmann/weather-api/config"
 	"github.com/robertoduessmann/weather-api/controller"
 )
 
@@ -13,7 +14,7 @@ func main() {
 	weather := mux.NewRouter()
 	weather.Path("/weather/{city}").Methods(http.MethodGet).HandlerFunc(controller.CurrentWeather)
 
-	if err := http.ListenAndServe(":3000", weather); err != nil {
+	if err := http.ListenAndServe(":"+config.Get().Port, weather); err != nil {
 		log.Fatal(err)
 	}