This content originally appeared on Level Up Coding - Medium and was authored by Clavin June
To use a random available port in Golang, you can use :0. I believe the port 0 would works for another language as well as I tried in python.
$ python -m SimpleHTTPServer 0
Serving HTTP on 0.0.0.0 port 43481 ...
According to lifewire, port 0 is a non-ephemeral port that works as a wildcard that tells the system to find any available ports particularly in the Unix OS.
The Go Code
package main
import (
"log"
"net"
"net/http"
)
func createListener() (l net.Listener, close func()) {
l, err := net.Listen("tcp", ":0")
if err != nil {
panic(err)
}return l, func() {
_ = l.Close()
}
}func main() {
l, close := createListener()
defer close()http.Handle("/", http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
// handle like normal
}))log.Println("listening at", l.Addr().(*net.TCPAddr).Port)
http.Serve(l, nil)
}Execute it:
$ go run main.go
2022/01/04 17:40:16 listening at 33845
Thank you for reading!
Originally published at https://clavinjune.dev on January 4, 2022.
Listening to Random Available Port in Go was originally published in Level Up Coding on Medium, where people are continuing the conversation by highlighting and responding to this story.
This content originally appeared on Level Up Coding - Medium and was authored by Clavin June
Clavin June | Sciencx (2022-01-04T14:59:20+00:00) Listening to Random Available Port in Go. Retrieved from https://www.scien.cx/2022/01/04/listening-to-random-available-port-in-go/
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