HttpTransport

For advanced scenarios, you can provide your own http.Client / http.Transport. You need to create your own http.Client, set its http.Transport, then configure the new client with elastic.SetHttpClient(...). Here is an example that changes all GET requests to POST.

// GetToPostTransport will change all GET requests to POST.
type GetToPostTransport struct {
	next http.RoundTripper  // next round-tripper (use http.DefaultTransport if nil)
}

// RoundTrip implements a transport that will change all GET requests to POST.
func (tr *GetToPostTransport) RoundTrip(r *http.Request) (*http.Response, error) {
        if r.Method == "GET" {
                r.Method = "POST"
        }
	if tr.next != nil {
		return tr.next.RoundTrip(r)
	}
	return http.DefaultTransport.RoundTrip(r)
}

...
myHttpClient := &http.Client{Transport: GetToPostTransport{}}
client, err := elastic.NewClient(elastic.SetHttpClient(myHttpClient))