fix(utils): honor Retry-After for 429 retries

pkg/utils/http_retry_test.go

@@ -80,6 +80,81 @@ func TestDoRequestWithRetry(t *testing.T) {
 	}
 }
 
+func TestDoRequestWithRetry_RetryAfter429Honored(t *testing.T) {
+	retryDelayUnit = 10 * time.Millisecond
+	t.Cleanup(func() { retryDelayUnit = time.Second })
+
+	attempts := 0
+	var firstAttemptAt time.Time
+	var secondAttemptAt time.Time
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		if attempts == 1 {
+			firstAttemptAt = time.Now()
+			w.Header().Set("Retry-After", "1")
+			w.WriteHeader(http.StatusTooManyRequests)
+			return
+		}
+		if attempts == 2 {
+			secondAttemptAt = time.Now()
+		}
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer server.Close()
+
+	client := &http.Client{Timeout: 5 * time.Second}
+	req, err := http.NewRequest(http.MethodGet, server.URL, nil)
+	require.NoError(t, err)
+
+	resp, err := DoRequestWithRetry(client, req)
+	require.NoError(t, err)
+	require.NotNil(t, resp)
+	assert.Equal(t, http.StatusOK, resp.StatusCode)
+	resp.Body.Close()
+	require.Equal(t, 2, attempts)
+
+	assert.GreaterOrEqual(t, secondAttemptAt.Sub(firstAttemptAt), 900*time.Millisecond)
+}
+
+func TestDoRequestWithRetry_RetryAfter429InvalidFallsBack(t *testing.T) {
+	retryDelayUnit = 50 * time.Millisecond
+	t.Cleanup(func() { retryDelayUnit = time.Second })
+
+	attempts := 0
+	var firstAttemptAt time.Time
+	var secondAttemptAt time.Time
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		if attempts == 1 {
+			firstAttemptAt = time.Now()
+			w.Header().Set("Retry-After", "invalid")
+			w.WriteHeader(http.StatusTooManyRequests)
+			return
+		}
+		if attempts == 2 {
+			secondAttemptAt = time.Now()
+		}
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer server.Close()
+
+	client := &http.Client{Timeout: 5 * time.Second}
+	req, err := http.NewRequest(http.MethodGet, server.URL, nil)
+	require.NoError(t, err)
+
+	resp, err := DoRequestWithRetry(client, req)
+	require.NoError(t, err)
+	require.NotNil(t, resp)
+	assert.Equal(t, http.StatusOK, resp.StatusCode)
+	resp.Body.Close()
+	require.Equal(t, 2, attempts)
+
+	assert.GreaterOrEqual(t, secondAttemptAt.Sub(firstAttemptAt), 45*time.Millisecond)
+	assert.Less(t, secondAttemptAt.Sub(firstAttemptAt), 500*time.Millisecond)
+}
+
 func TestDoRequestWithRetry_ContextCancel(t *testing.T) {
 	// Use a long retry delay so cancellation always hits during sleepWithCtx.
 	retryDelayUnit = 10 * time.Second