[CI] Refactor disaggregation tests (#10068)

Signed-off-by: Shangming Cai <csmthu@gmail.com>

python/sglang/test/test_disaggregation_utils.py

@@ -0,0 +1,66 @@
+import time
+
+import requests
+
+from sglang.srt.utils import kill_process_tree
+from sglang.test.test_utils import (
+    DEFAULT_TIMEOUT_FOR_SERVER_LAUNCH,
+    CustomTestCase,
+    popen_with_error_check,
+)
+
+
+class TestDisaggregationBase(CustomTestCase):
+    @classmethod
+    def setUpClass(cls):
+        cls.process_lb, cls.process_decode, cls.process_prefill = None, None, None
+        pass
+
+    @classmethod
+    def launch_lb(cls):
+        lb_command = [
+            "python3",
+            "-m",
+            "sglang_router.launch_router",
+            "--pd-disaggregation",
+            "--mini-lb",  # FIXME: remove this
+            "--prefill",
+            cls.prefill_url,
+            "--decode",
+            cls.decode_url,
+            "--host",
+            cls.base_host,
+            "--port",
+            cls.lb_port,
+        ]
+        print("Starting load balancer:", " ".join(lb_command))
+        cls.process_lb = popen_with_error_check(lb_command)
+        cls.wait_server_ready(cls.lb_url + "/health")
+
+    @classmethod
+    def wait_server_ready(cls, url, timeout=DEFAULT_TIMEOUT_FOR_SERVER_LAUNCH):
+        start_time = time.perf_counter()
+        while True:
+            try:
+                response = requests.get(url)
+                if response.status_code == 200:
+                    print(f"Server {url} is ready")
+                    return
+            except Exception:
+                pass
+
+            if time.perf_counter() - start_time > timeout:
+                raise RuntimeError(f"Server {url} failed to start in {timeout}s")
+            time.sleep(1)
+
+    @classmethod
+    def tearDownClass(cls):
+        for process in [cls.process_lb, cls.process_decode, cls.process_prefill]:
+            if process:
+                try:
+                    kill_process_tree(process.pid)
+                except Exception as e:
+                    print(f"Error killing process {process.pid}: {e}")
+
+        # wait for 5 seconds
+        time.sleep(5)