Should be able to deploy

backend/main.go

@@ -41,12 +41,14 @@ func main() {
 	environ := os.Getenv("ENVIRONMENT")
 
 	port := os.Getenv("BACKEND_DOCKER_PORT")
+	hostname := os.Getenv("DATABASE_HOSTNAME")
 	if environ == "DEV" {
 		port = os.Getenv("BACKEND_PORT")
+		hostname = "localhost"
 	}
 
 	dsn := core.DSN{
-		Hostname: "localhost",
+		Hostname: hostname,
 		Port:     os.Getenv("POSTGRES_PORT"),
 		DBName:   os.Getenv("POSTGRES_DB"),
 		User:     os.Getenv("POSTGRES_USER"),