fix: pod logs streaming blocked by cleanResponseMiddleware buffering. Fixes #3470

server/routes/clean_response_middleware.go

@@ -46,6 +46,12 @@ func (w customResponseWriter) WriteString(s string) (int, error) {
 // cleanResponseMiddleware is a Gin middleware to clean up data in the response body.
 func cleanResponseMiddleware() gin.HandlerFunc {
 	return func(c *gin.Context) {
+		// Skip buffering for streaming endpoints (e.g. pod logs with follow=true),
+		// otherwise the response would never be written to the client.
+		if strings.HasSuffix(c.FullPath(), "/pods/:pod/logs") {
+			c.Next()
+			return
+		}
 		// Replace the original response writer with our custom one
 		w := &customResponseWriter{body: bytes.NewBufferString(""), ResponseWriter: c.Writer}
 		c.Writer = w

server/routes/clean_response_middleware_test.go

@@ -397,6 +397,31 @@ func TestCustomResponseWriter_Write(t *testing.T) {
 	})
 }
 
+func TestCleanResponseMiddleware_SkipsPodLogsStreaming(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+
+	t.Run("pod logs route bypasses response buffering", func(t *testing.T) {
+		router := gin.New()
+		router.Use(cleanResponseMiddleware())
+
+		w := httptest.NewRecorder()
+		var bytesReceivedDuringHandler int
+		router.GET("/api/v1/namespaces/:namespace/pods/:pod/logs", func(c *gin.Context) {
+			_, _ = c.Writer.WriteString("log line 1\n")
+			c.Writer.Flush()
+			bytesReceivedDuringHandler = w.Body.Len()
+			_, _ = c.Writer.WriteString("log line 2\n")
+		})
+
+		req, _ := http.NewRequest(http.MethodGet, "/api/v1/namespaces/ns/pods/my-pod/logs?container=numa&follow=true", nil)
+		router.ServeHTTP(w, req)
+
+		assert.Greater(t, bytesReceivedDuringHandler, 0, "logs should reach the client while the handler is still streaming")
+		assert.Equal(t, http.StatusOK, w.Code)
+		assert.Equal(t, "log line 1\nlog line 2\n", w.Body.String())
+	})
+}
+
 func TestCleanResponseMiddleware_EdgeCases(t *testing.T) {
 	gin.SetMode(gin.TestMode)