Read request body on first try

Even if successful by always reading the body we can make certain that
the body will be sent to the server, even if the request fails before
reading the body. See parent commit for further reference.

Signed-off-by: Leandro López (inkel) <leandro.lopez@grafana.com>

Author: inkel

client.go

@@ -71,28 +71,22 @@ func (c Client) WithOrgID(orgID int64) *Client {
 	return &c
 }
 
-func (c *Client) request(method, requestPath string, query url.Values, body io.Reader, responseStruct interface{}) error {
+func (c *Client) request(method, requestPath string, query url.Values, bodyRd io.Reader, responseStruct interface{}) error {
 	var (
 		req          *http.Request
 		resp         *http.Response
 		err          error
 		bodyContents []byte
 	)
 
-	// If we want to retry a request that sends data, we'll need to stash the request data in memory. Otherwise, we lose it since readers cannot be replayed.
-	var bodyBuffer bytes.Buffer
-	if c.config.NumRetries > 0 && body != nil {
-		body = io.TeeReader(body, &bodyBuffer)
+	body, err := io.ReadAll(bodyRd)
+	if err != nil {
+		return fmt.Errorf("cannot read request body: %w", err)
 	}
 
 	// retry logic
 	for n := 0; n <= c.config.NumRetries; n++ {
-		// If it's not the first request, re-use the request body we stashed earlier.
-		if n > 0 {
-			body = bytes.NewReader(bodyBuffer.Bytes())
-		}
-
-		req, err = c.newRequest(method, requestPath, query, body)
+		req, err = c.newRequest(method, requestPath, query, bytes.NewReader(body))
 		if err != nil {
 			return err
 		}