Making service to be opened on dynamic port by making serice an insta…

…nce var

cmd/main.go

@@ -5,5 +5,6 @@ import (
 )
 
 func main() {
- service.Start()
+ service := service.Service{}
+ service.Start("")
 }

service/service.go

@@ -3,6 +3,10 @@ package service
 import (
  "net/http"
  "time"
+ "log"
+ "os"
+ "os/signal"
+ "context"
 
  "pricingengine/service/app"
  "pricingengine/service/rpc"
@@ -12,7 +16,11 @@ import (
 )
 
 // Start begins a chi-Mux'd net/http server on port 3000
-func Start() {
+type Service struct {
+ Server *http.Server
+}
+
+func (s * Service)Start(port string) {
  r := chi.NewRouter()
 
  r.Use(middleware.Logger)
@@ -21,8 +29,43 @@ func Start() {
  rpc := rpc.RPC{
  App: &app.App{},
  }
-
+ if len(port) == 0 {
+ // default port 3000
+ port = "3000"
+ }
  r.Post("/generate_pricing", rpc.GeneratePricing)
  r.Get("/generate_pricing", rpc.GeneratePricingConfig)
- http.ListenAndServe(":3000", r)
+ s.ListenAndServe(":"+port, r)
+}
+
+func (s *Service)ListenAndServe(port string, r http.Handler) {
+ log.Println("Starting Server!")
+ s.Server = &http.Server{Addr: port, Handler: r}
+ if err := s.Server.ListenAndServe(); err != nil {
+ // handle err
+ }
+
+ // Setting up signal capturing
+ stop := make(chan os.Signal, 1)
+ signal.Notify(stop, os.Interrupt)
+
+ // Waiting for SIGINT (pkill -2)
+ <-stop
+ log.Println("Received Server Stop!")
+ s.Stop()
+ // Wait for ListenAndServe goroutine to close.
+}
+
+// check and stop the currently running http server
+func (s * Service)Stop() {
+ log.Println("Stopping Server!")
+ ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+ defer cancel()
+ if s.Server != nil {
+ log.Println(" Initiating Server Shutdown!")
+ if err := s.Server.Shutdown(ctx); err != nil {
+ // handle err
+ log.Println("Error while stopping Server!", err)
+ }
+ }
 }