Posting json data to remote server with http.Post - json

Question

I am stumped on what seems like a very simple problem.
I am receiving a json object from a client. It looks like this:
{
"user": "test#example.com"
}
I need to simply pass this on to another part of the api as a POST request. This is what i've got until now:
//Decode incomming json
decoder := json.NewDecoder(r.Body)
var user UserInformation
err := decoder.Decode(&user)
if err != nil {
log.Println(err)
}
jsonUser, _ := json.Marshal(user)
log.Println(string(jsonUser[:])) //Correct output
buffer := bytes.NewBuffer(jsonUser)
log.Println(string(buffer.Bytes()[:])) //Also correct
resp, err := http.Post("http://example.com/api/has_publisher", "application/json", buffer)
if err != nil {
log.Println(err)
}
As I cannot test this program on a live system, I verified the resulting post request with wireshark only to find that the content is missing along with Content-Length being 0. For some reason, http.Post doesn't read from the buffer.
Am i missing something here? I would greatly appreciate if someone could point me in the right direction.
Thanks!

Answer 1

Shouldn`t be the root cause but replace
buffer := bytes.NewBuffer(jsonUser)
with
buffer := bytes.NewReader(jsonUser)
It is more likely that your test setup is the root cause. I assume you are pointing to a non-existing endpoint. This would result in a failure (TCP SYN fails) before the actual HTTP POST is send.
Check if you can use mockable.io as an alternative to mock your backend.