[Serve][Core] Refactor serve tail logs to serve core

sky/backends/cloud_vm_ray_backend.py

@@ -35,7 +35,6 @@
 from sky import optimizer
 from sky import provision as provision_lib
 from sky import resources as resources_lib
-from sky import serve as serve_lib
 from sky import sky_logging
 from sky import status_lib
 from sky import task as task_lib
@@ -4037,43 +4036,6 @@ def _rsync_down(args) -> None:
                     f'{colorama.Style.RESET_ALL}')
         return {str(job_id): local_log_dir}
 
-    def tail_serve_logs(self, handle: CloudVmRayResourceHandle,
-                        service_name: str, target: serve_lib.ServiceComponent,
-                        replica_id: Optional[int], follow: bool) -> None:
-        """Tail the logs of a service.
-
-        Args:
-            handle: The handle to the sky serve controller.
-            service_name: The name of the service.
-            target: The component to tail the logs of. Could be controller,
-                load balancer, or replica.
-            replica_id: The replica ID to tail the logs of. Only used when
-                target is replica.
-            follow: Whether to follow the logs.
-        """
-        if target != serve_lib.ServiceComponent.REPLICA:
-            code = serve_lib.ServeCodeGen.stream_serve_process_logs(
-                service_name,
-                stream_controller=(
-                    target == serve_lib.ServiceComponent.CONTROLLER),
-                follow=follow)
-        else:
-            assert replica_id is not None, service_name
-            code = serve_lib.ServeCodeGen.stream_replica_logs(
-                service_name, replica_id, follow)
-
-        signal.signal(signal.SIGINT, backend_utils.interrupt_handler)
-        signal.signal(signal.SIGTSTP, backend_utils.stop_handler)
-
-        self.run_on_head(
-            handle,
-            code,
-            stream_logs=True,
-            process_stream=False,
-            ssh_mode=command_runner.SshMode.INTERACTIVE,
-            stdin=subprocess.DEVNULL,
-        )
-
     def teardown_no_lock(self,
                          handle: CloudVmRayResourceHandle,
                          terminate: bool,

sky/serve/core.py

@@ -1,6 +1,9 @@
 """SkyServe core APIs."""
 import re
+import signal
+import subprocess
 import tempfile
+import threading
 from typing import Any, Dict, List, Optional, Tuple, Union
 
 import colorama
@@ -18,6 +21,7 @@
 from sky.skylet import constants
 from sky.usage import usage_lib
 from sky.utils import admin_policy_utils
+from sky.utils import command_runner
 from sky.utils import common_utils
 from sky.utils import controller_utils
 from sky.utils import resources_utils
@@ -731,8 +735,27 @@ def tail_logs(
 
     backend = backend_utils.get_backend_from_handle(handle)
     assert isinstance(backend, backends.CloudVmRayBackend), backend
-    backend.tail_serve_logs(handle,
-                            service_name,
-                            target,
-                            replica_id,
-                            follow=follow)
+
+    if target != serve_utils.ServiceComponent.REPLICA:
+        code = serve_utils.ServeCodeGen.stream_serve_process_logs(
+            service_name,
+            stream_controller=(
+                target == serve_utils.ServiceComponent.CONTROLLER),
+            follow=follow)
+    else:
+        assert replica_id is not None, service_name
+        code = serve_utils.ServeCodeGen.stream_replica_logs(
+            service_name, replica_id, follow)
+
+    # With the stdin=subprocess.DEVNULL, the ctrl-c will not directly
+    # kill the process, so we need to handle it manually here.
+    if threading.current_thread() is threading.main_thread():
+        signal.signal(signal.SIGINT, backend_utils.interrupt_handler)
+        signal.signal(signal.SIGTSTP, backend_utils.stop_handler)
+
+    backend.run_on_head(handle,
+                        code,
+                        stream_logs=True,
+                        process_stream=False,
+                        ssh_mode=command_runner.SshMode.INTERACTIVE,
+                        stdin=subprocess.DEVNULL)