package main

import (
	"log"
	"net/http"
)

func main() {
	router := NewRouter()
	err := http.ListenAndServe(":" + os.Getenv("PORT"), router)
	if err != nil {
		log.Fatal("ListenAndServe Error: ", err)
	}
}

package main

import (
	"log"
	"net/http"
)

func main() {
	router := NewRouter()
	err := http.ListenAndServe(":8080", router)
	if err != nil {
		log.Fatal("ListenAndServe Error: ", err)
	}
}

--- 
+++ 
@@ -7,7 +7,7 @@
 
 func main() {
 	router := NewRouter()
-	err := http.ListenAndServe(":8080", router)
+	err := http.ListenAndServe(":" + os.Getenv("PORT"), router)
 	if err != nil {
 		log.Fatal("ListenAndServe Error: ", err)
 	}
Make http port into env var
