golang http client returning wrong content type

Question

I have a very simple Go program that performs HTTP HEAD on a URL, and prints the content-type of the response:

package main
import (
        "fmt"
        "net/http"
)
func main() {
        resp, _ := http.Head("https://jira.softwareplant.com/servicedesk/customer/portal/1/")
        fmt.Println(resp.Header.Get("Content-Type"))
}

When I run it, it returns the following:

$ go run url.go
application/octet-stream;charset=UTF-8

However, when I do the same using curl, it returns a different content type (both in the original response, and after the redirect):

$ curl -I -L https://jira.softwareplant.com/servicedesk/customer/portal/1/
HTTP/1.1 302
Date: Thu, 11 Jun 2020 18:07:26 GMT
Content-Type: text/html;charset=UTF-8
Connection: keep-alive
X-AREQUESTID: 1207x5410258x1
X-XSS-Protection: 1; mode=block
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN
Content-Security-Policy: frame-ancestors 'self'
X-ASEN: SEN-L15483924
Set-Cookie: atlassian.xsrf.token=BWV3-4JDO-FP3E-CBA1_b0942d30c14d689f92051e7b2d8467e0a0ce2129_lout; Path=/; Secure
Set-Cookie: JSESSIONID=8FE57CA54FEC626F0521327DCBA1D3DB; Path=/; Secure; HttpOnly
X-ASESSIONID: 18hzbge
X-AUSERNAME: anonymous
Location: /plugins/servlet/desk/portal/1/

HTTP/1.1 302
Date: Thu, 11 Jun 2020 18:07:26 GMT
Content-Type: text/html;charset=UTF-8
Connection: keep-alive
X-AREQUESTID: 1207x5410259x1
X-XSS-Protection: 1; mode=block
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN
Content-Security-Policy: frame-ancestors 'self'
X-ASEN: SEN-L15483924
Set-Cookie: atlassian.xsrf.token=BWV3-4JDO-FP3E-CBA1_fcd3f481d084e039075ebbce34039870d7cd044d_lout; Path=/; Secure
Set-Cookie: JSESSIONID=7B895577760D8E31F02B818FA8C0E1B2; Path=/; Secure; HttpOnly
X-ASESSIONID: 289ito
X-AUSERNAME: anonymous
Location: /servicedesk/customer/portal/1//user/login?destination=portal%2F1/

HTTP/1.1 200
Date: Thu, 11 Jun 2020 18:07:26 GMT
Content-Type: text/html;charset=UTF-8
Connection: keep-alive
X-AREQUESTID: 1207x5410260x1
X-XSS-Protection: 1; mode=block
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN
Content-Security-Policy: frame-ancestors 'self'
X-ASEN: SEN-L15483924
Set-Cookie: atlassian.xsrf.token=BWV3-4JDO-FP3E-CBA1_dc371dbc76497b29f1fa939a65dc6dd5b3488e7f_lout; Path=/; Secure
Set-Cookie: JSESSIONID=E17E2F0C4B7CA5C9ADDC4BE468A5D459; Path=/; Secure; HttpOnly
X-ASESSIONID: 1byquf1
X-AUSERNAME: anonymous
Cache-Control: no-cache, no-store, no-transform

Am I doing something wrong? Is there a way in Go to get the correct content-type for such URLs? I am using Golang 1.14.4 on Ubuntu. The above URL is not the only one that has this issue.

Answer 1

If you change the Accept header sent by Go, you will get Content-Type: text/html;charset=UTF-8:

package main

import (
        "fmt"
        "net/http"
)

func main() {
        client := &http.Client{}
        req, _ := http.NewRequest("HEAD", "https://jira.softwareplant.com/servicedesk/customer/portal/1/", nil)
        req.Header.Set("Accept", "*/*")
        resp, _ := client.Do(req)
        fmt.Println(resp.Header.Get("Content-Type"))
}