follow redirects with go and collect all the cookies returned

getcookies.go

import (                                                                                                                                                                  
        "fmt"                                                                                                                                                             
        "io/ioutil"                                                                                                                                                       
        "log"                                                                                                                                                             
        "net/http"                                                                                                                                                        
        "strings"                                                                                                                                                         
)                                                                                                                                                                         
                                                                                                                                                                          
// main, do not ignore errors like this in production                                                                                                                     
func main() {                                                                                                                                                             
        url := "https://www.vinmonopolet.no/api/products/546402?fields=FULL"                                                                                              
        cookies, err := followRedirectsWithCookies(url)                                                                                                                   
        if err != nil {                                                                                                                                                   
                log.Fatalf("Something bad happened, %v", err)                                                                                                             
        }                                                                                                                                                                 
        req, _ := http.NewRequest("GET", url, nil)                                                                                                                        
        for _, c := range cookies {                                                                                                                                       
                req.AddCookie(c)                                                                                                                                          
        }                                                                                                                                                                 
                                                                                                                                                                          
        resp, _ := http.DefaultClient.Do(req)                                                                                                                             
        body, _ := ioutil.ReadAll(resp.Body)                                                                                                                              
        log.Printf("got response\n\n\t%s", body)                                                                                                                          
                                                                                                                                                                          
}                                                                                                                                                                         
                                                                                                                                                                          
func followRedirectsWithCookies(url string) ([]*http.Cookie, error) {                                                                                                     
                                                                                                                                                                          
        cookies := make([]*http.Cookie, 0)                                                                                                                                
        transport := http.Transport{}                                                                                                                                     
                                                                                                                                                                          
        location := url                                                                                                                                                   
                                                                                                                                                                          
        for {                                                                                                                                                             
                req, err := http.NewRequest("GET", location, nil)                                                                                                         
                if err != nil {                                                                                                                                           
                        return nil, err                                                                                                                                   
                }                                                                                                                                                         
                for _, c := range cookies {                                                                                                                               
                        req.AddCookie(c)                                                                                                                                  
                }                                                                                                                                                         
                resp, err := transport.RoundTrip(req)                                                                                                                     
                if err != nil {                                                                                                                                           
                        return nil, err                                                                                                                                   
                }                                                                                                                                                         
                if resp.Cookies() != nil {                                                                                                                                
                        cookies = append(cookies, resp.Cookies()...)                                                                                                      
                }                                                                                                                                                         
                if resp.StatusCode != 302 {                                                                                                                               
                        log.Printf("\nGot final url at %s", location)                                                                                                     
                        break                                                                                                                                             
                } else {                                                                                                                                                  
                        location = resp.Header.Get("Location")                                                                                                            
                        fmt.Printf("...%s", location)                                                                                                                     
                                                                                                                                                                          
                        if !strings.HasPrefix(location, "https") {                                                                                                        
                                location = fmt.Sprintf("https://%s%s", req.Host, location)                                                                                
                        }                                                                                                                                                 
                                                                                                                                                                          
                }                                                                                                                                                         
        }                                                                                                                                                                 
                                                                                                                                                                          
        return cookies, nil                                                                                                                                               
}