Check if a URL is reachable using Golang - http

Question

I want to create a simple script that checks if a certain hostname:port is running. I only want to get a bool response if that URL is live, but I'm not sure if there's a straightforward way of doing it.

Answer 1

If you only want see if a URL is reachable you could use net.DialTimeout. Like this:
timeout := 1 * time.Second
conn, err := net.DialTimeout("tcp","mysyte:myport", timeout)
if err != nil {
log.Println("Site unreachable, error: ", err)
}

Answer 2

If you want to check if a Web server answers on a certain URL, you can invoke an HTTP GET request using net/http.
You will get a timeout if the server doesn't response at all. You might also check the response status.
resp, err := http.Get("http://google.com/")
if err != nil {
print(err.Error())
} else {
print(string(resp.StatusCode) + resp.Status)
}
You can change the default timeout by initializing a http.Client.
timeout := time.Duration(1 * time.Second)
client := http.Client{
Timeout: timeout,
}
resp, err := client.Get("http://google.com")
Bonus:
Go generally does not rely on exceptions and the built in libraries generally do not panic, but return an error as a second value.
See Why does Go not have exceptions?.
You can assume that something very bad happened if your call to a native function panics.

Answer 3

You can make a HEAD request:
package main
import "net/http"
func head(s string) bool {
r, e := http.Head(s)
return e == nil && r.StatusCode == 200
}
func main() {
b := head("https://stackoverflow.com")
println(b)
}
https://golang.org/pkg/net/http#Head

Answer 4

If you don't mind the port, use http.Get(web):
package main
import (
"fmt"
"net/http"
"os"
)
func main() {
web := os.Args[1]
fmt.Println(webIsReachable(web))
}
func webIsReachable(web string) bool {
response, errors := http.Get(web)
if errors != nil {
_, netErrors := http.Get("https://www.google.com")
if netErrors != nil {
fmt.Fprintf(os.Stderr, "no internet\n")
os.Exit(1)
}
return false
}
if response.StatusCode == 200 {
return true
}
return false
}