fix(runtime): skip default retries for unsafe methods

pkg/runtime/client.go

@@ -55,11 +55,12 @@ func HTTPClient(opts ClientOptions) *http.Client {
 		transport = &http.Transport{TLSClientConfig: tlsCfg}
 	}
 	maxRetries := opts.MaxRetries
-	if maxRetries == 0 {
+	safeMethodsOnly := maxRetries == 0
+	if safeMethodsOnly {
 		maxRetries = 3
 	}
 	if maxRetries > 0 {
-		transport = &retryTransport{inner: transport, maxRetries: maxRetries, debug: opts.Debug}
+		transport = &retryTransport{inner: transport, maxRetries: maxRetries, debug: opts.Debug, safeMethodsOnly: safeMethodsOnly}
 	}
 	if opts.Debug {
 		transport = &debugTransport{inner: transport}

pkg/runtime/retry.go

@@ -10,10 +10,11 @@ import (
 )
 
 type retryTransport struct {
-	inner      http.RoundTripper
-	maxRetries int
-	sleepFn    func(time.Duration)
-	debug      bool
+	inner           http.RoundTripper
+	maxRetries      int
+	sleepFn         func(time.Duration)
+	debug           bool
+	safeMethodsOnly bool
 }
 
 func (t *retryTransport) RoundTrip(req *http.Request) (*http.Response, error) {
@@ -48,7 +49,7 @@ func (t *retryTransport) RoundTrip(req *http.Request) (*http.Response, error) {
 		if err != nil {
 			return nil, err
 		}
-		if !isRetryable(resp.StatusCode) {
+		if !isRetryable(req.Method, resp.StatusCode, t.safeMethodsOnly) {
 			return resp, nil
 		}
 		if attempt < t.maxRetries {
@@ -58,9 +59,17 @@ func (t *retryTransport) RoundTrip(req *http.Request) (*http.Response, error) {
 	return resp, nil
 }
 
-func isRetryable(status int) bool {
+func isRetryable(method string, status int, safeMethodsOnly bool) bool {
 	switch status {
 	case 429, 500, 502, 503, 504:
+	default:
+		return false
+	}
+	if !safeMethodsOnly {
+		return true
+	}
+	switch method {
+	case http.MethodGet, http.MethodHead, http.MethodOptions:
 		return true
 	}
 	return false

pkg/runtime/retry_test.go

@@ -75,6 +75,32 @@ func TestRetryTransport_RetriesOn5xx(t *testing.T) {
 	}
 }
 
+func TestHTTPClient_DefaultRetriesSkipPost(t *testing.T) {
+	var calls int32
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if atomic.AddInt32(&calls, 1) > 1 {
+			w.WriteHeader(200)
+			return
+		}
+		w.WriteHeader(500)
+	}))
+	defer srv.Close()
+
+	req, _ := http.NewRequestWithContext(context.Background(), "POST", srv.URL, strings.NewReader(`{"key":"val"}`))
+	resp, err := HTTPClient(ClientOptions{Timeout: 3 * time.Second}).Do(req)
+	if err != nil {
+		t.Fatalf("Do: %v", err)
+	}
+	resp.Body.Close()
+
+	if resp.StatusCode != 500 {
+		t.Fatalf("status = %d, want 500", resp.StatusCode)
+	}
+	if got := atomic.LoadInt32(&calls); got != 1 {
+		t.Fatalf("calls = %d, want 1", got)
+	}
+}
+
 func TestRetryTransport_NoRetryOn4xx(t *testing.T) {
 	var calls int32
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {