Prepare http server to run another service in parallel

main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+ "context"
  "embed"
  "encoding/json"
  "fmt"
@@ -9,8 +10,10 @@ import (
  "io/fs"
  "net/http"
  "os"
+ "os/signal"
  "path"
  "strings"
+ "syscall"
  "time"
 
  "github.com/rs/zerolog"
@@ -111,10 +114,33 @@ func createModule(config *Config, moduleName string) modules.Module {
 }
 
 func run(cmd *cobra.Command, args []string) {
+ // Logging
+ configureLoggers()
+
  config := parseConfigFile(configFilePath)
  module := createModule(config, moduleName)
 
- runServer(config, module)
+ ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
+ defer stop()
+
+ srv := runHttpServer(config, module)
+
+ // Listen for the interrupt signal.
+ <-ctx.Done()
+
+ // Restore default behavior on the interrupt signal and notify user of shutdown.
+ stop()
+ mainLogger.Info().Msg("Shutting down gracefully, press Ctrl+C again to force")
+
+ // The context is used to inform the server it has 5 seconds to finish
+ // the request it is currently handling
+ ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+ defer cancel()
+ if err := srv.Shutdown(ctx); err != nil {
+ mainLogger.Fatal().Err(err).Msg("Server forced to shutdown")
+ }
+
+ mainLogger.Info().Msg("Server exiting")
 }
 
 //go:embed index.html
@@ -129,6 +155,20 @@ var (
  mainLogger zerolog.Logger
 )
 
+func resolveAddress() string {
+ port := os.Getenv("PORT")
+ if port != "" {
+ mainLogger.
+ Debug().
+ Msg(fmt.Sprintf("Environment variable PORT=\"%s\"", port))
+ return ":" + port
+ }
+ mainLogger.
+ Debug().
+ Msg("Environment variable PORT is undefined. Using port :8080 by default")
+ return ":8080"
+}
+
 func configureLoggers() {
  zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
  var outputWriter io.Writer = os.Stderr
@@ -171,7 +211,7 @@ func loggerWithZerolog(logger *zerolog.Logger) gin.HandlerFunc {
  }
 }
 
-func runServer(config *Config, module modules.Module) {
+func runHttpServer(config *Config, module modules.Module) *http.Server {
  // Configure Gin
  router := gin.New()
  router.Use(loggerWithZerolog(&ginLogger))
@@ -180,9 +220,6 @@ func runServer(config *Config, module modules.Module) {
  html := template.Must(template.ParseFS(templateFS, "index.html"))
  router.SetHTMLTemplate(html)
 
- // Logging
- configureLoggers()
-
  // Serve static folder
  staticSubtreeFS, err := fs.Sub(staticFS, "static")
  if err != nil {
@@ -277,7 +314,19 @@ func runServer(config *Config, module modules.Module) {
  })
  }
 
- router.Run()
+ srv := &http.Server{
+ Addr: resolveAddress(),
+ Handler: router,
+ }
+
+ go func() {
+ err := srv.ListenAndServe()
+ if err != nil && err != http.ErrServerClosed {
+ mainLogger.Fatal().Err(err).Msg("An error occurred while starting the server")
+ }
+ }()
+
+ return srv
 }
 
 func init() {