How to close http port in go?

In the Go language, closing the HTTP port can be achieved by using the `Close()` method of `http.Server`. First, we need to create an `http.Server` instance and listen on the specified port. Once the server is running, we can stop the server by calling the `Close()` method. This will cause the running HTTP server to stop immediately and release the listening port. In addition, we can also use semaphores to shut down the HTTP server gracefully, such as using the `os.Interrupt` signal to capture the Ctrl C event and shut down the server when the signal is received. In short, the Go language provides a simple and flexible method to close the HTTP port, allowing us to better control the operation of the server.

Question content

I just learned go and create simple web applications. But every time I start localhost in go (even if I stop the process in terminal), it doesn't close the port. So how do I turn it off.

This is the code

const portNumber = ":8080"
func main() {
http.HandleFunc("/", Home)
http.HandleFunc("/about", About)

fmt.Println(fmt.Sprintf("Starting on port %s", portNumber))
_ = http.ListenAndServe(portNumber, nil)
}

I did research online but couldn't find a solution so I hope you can help me. Thank you

SOLUTION

I think the first important thing is to rephrase your question and really understand what you are asking. There is no such thing as a closed http port. This is how http server works at a very high level:

1. So when you ask an http server to start listening on a certain port, you are basically asking the operating system to create an internet socket that represents the endpoint. By endpoint, I mean ip:port.

2. In the case of http 1, 1.1 and 2, the socket is specifically a tcp internet socket.

3. The socket is running in the listening phase and is listening for any incoming connection requests. If it receives any incoming request then the kernel will simply do a 3 way tcp handshake and after a successful handshake the kernel creates a connection object and hands it over to the process representing the backend application where you will listen for any A new connection is created. So you will see that the port has always existed in your system, you did not create a new port when you started the http server, but basically created an internet socket object and asked your kernel to start listening to the port for New connection and hand it over to your backend application when the connection is created. So you're basically asking me how to stop listening at that endpoint and ask the kernel to delete that internet socket. Below is a rough code snippet to give you an idea of ​​how to do this.

   import (
    "context"
    "log"
    "net/http"
    "os"
    "os/signal"
    "syscall"
    "time"
    )
    func main() {
        server := &http.Server{Addr: ":8080", Handler: myHandler}
        go server.ListenAndServe()
   
        interrupt := make(chan os.Signal, 1)
        signal.Notify(interrupt, os.Interrupt, syscall.SIGTERM)
   
        <-interrupt
        log.Println("Shutting down server...")
   
        ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
        defer cancel()
   
        if err := server.Shutdown(ctx); err != nil {
            log.Fatal("Server forced to shutdown:", err)
        }
        log.Println("Server stopped")
    }
   
    func myHandler(w http.ResponseWriter, r *http.Request) {
        // Handle requests
    }

   Copy after login

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