golang http helloworld doesn't block

Question

My code is just the same as in gowiki

package main

import (
    "fmt"
    "net/http"
)

func handler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Hi there, I love %s!", r.URL.Path[1:])
}

func main() {
    http.HandleFunc("/", handler)
    http.ListenAndServe(":8080", nil)
}

However, after I build and run this program, it exit immediately without blocking so that I get no response when I try to access http://localhost:8080/monkey from Chrome.

Environment: Ubuntu 14(in VirtualBox on Windows7)

Why?

Do you have anything else using port 8080? Are there any error messages? — Rowland Shaw
– Rowland Shaw, Commented Aug 4, 2014 at 15:11

OneOfOne · Accepted Answer · 2014-08-04 15:15:39Z

20

Check the error returned from ListenAndServe

func main() {
    http.HandleFunc("/", handler)
    fmt.Println(http.ListenAndServe(":8080", nil))
}

answered Aug 4, 2014 at 15:15

OneOfOne

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Comments

Rostyslav Dzinko · Accepted Answer · 2014-08-04 15:49:14Z

5

http.ListenAndServe function returns an object that conforms error interface. If the call does not block, it definitely means that some kind of error has happened. The most popular are:

there is already another process listening that port
your user has no right to bind socket on port 8080, or 0.0.0.0 interface

answered Aug 4, 2014 at 15:49

Rostyslav Dzinko

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Comments

Harshith Vasireddy · Accepted Answer · 2020-03-23 10:47:00Z

1

In my case, it was a permission denied error. Using sudo worked like a charm.

sudo go run filename.go

or

sudo filename

answered Mar 23, 2020 at 10:47

Harshith Vasireddy

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