package main

import (
    "fmt"
    "net/http"
    "time"
)

func main() {
    http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        time.Sleep(3*time.Second)
        fmt.Fprintf(w, "req rcvd")
    })
    http.ListenAndServe(":8080", nil)
}

package main

import (
    "fmt"
    "io/ioutil"
    "net"
    "net/http"
    "net/url"
    "time"
)

func main() {
    client := &http.Client{
        Timeout: time.Duration(time.Second),
    }

    req, err := client.Get("http://localhost:8080")
    if err != nil {
        fmt.Printf("type: %T\n", err)
        fmt.Printf("error: %v\n", err)
        if err2, ok := err.(*url.Error); ok {
            fmt.Printf("inner type: %T\n", err2.Err)
            fmt.Printf("inner error: %v\n", err2.Err)
            if err3, ok := err2.Err.(net.Error); ok {
                fmt.Printf("is timeout: %v\n", err3.Timeout())
            }
            if err4, ok := err2.Err.(*net.OpError); ok {
                fmt.Printf("OpError inner type: %T\n", err4.Err)
                fmt.Printf("OpError inner error: %v\n", err4.Err)
            }
        }
        return
    }

    resp, err := ioutil.ReadAll(req.Body)
    req.Body.Close()
    if err != nil {
        fmt.Println(err)
    }
    fmt.Printf("%s", resp)
}