[cli][ray] ray start should error by default if there's already an instance running (#10826)

python/ray/scripts/scripts.py

@@ -10,6 +10,7 @@ import time
 import urllib
 import urllib.parse
 import yaml
+from socket import socket
 
 import ray
 import psutil
@@ -160,11 +161,11 @@ def dashboard(cluster_config_file, cluster_name, port, remote_port):
     "--address", required=False, type=str, help="the address to use for Ray")
 @click.option(
     "--port",
+    type=int,
     required=False,
-    type=str,
-    help="the port of the head ray process. If not provided, tries to use "
-    "{0}, falling back to a random port if {0} is "
-    "not available".format(ray_constants.DEFAULT_PORT))
+    help=f"the port of the head ray process. If not provided, defaults to "
+    f"{ray_constants.DEFAULT_PORT}; if port is set to 0, we will"
+    f" allocate an available port.")
 @click.option(
     "--redis-password",
     required=False,
@@ -368,7 +369,6 @@ def start(node_ip_address, address, port, redis_password, redis_shard_ports,
           log_color, verbose):
     """Start Ray processes manually on the local machine."""
     cli_logger.configure(log_style, log_color, verbose)
-
     if gcs_server_port and not head:
         raise ValueError(
             "gcs_server_port can be only assigned when you specify --head.")
@@ -381,7 +381,6 @@ def start(node_ip_address, address, port, redis_password, redis_shard_ports,
     if address is not None:
         (redis_address, redis_address_ip,
          redis_address_port) = services.validate_redis_address(address)
-
     try:
         resources = json.loads(resources)
     except Exception:
@@ -430,6 +429,15 @@ def start(node_ip_address, address, port, redis_password, redis_shard_ports,
         enable_object_reconstruction=enable_object_reconstruction,
         metrics_export_port=metrics_export_port)
     if head:
+        # Use default if port is none, allocate an available port if port is 0
+        if port is None:
+            port = ray_constants.DEFAULT_PORT
+
+        if port == 0:
+            with socket() as s:
+                s.bind(("", 0))
+                port = s.getsockname()[1]
+
         num_redis_shards = None
         # Start Ray on the head node.
         if redis_shard_ports is not None:
@@ -447,9 +455,10 @@ def start(node_ip_address, address, port, redis_password, redis_shard_ports,
                             "started, so a Redis address should not be "
                             "provided.")
 
+        node_ip_address = services.get_node_ip_address()
+
         # Get the node IP address if one is not provided.
-        ray_params.update_if_absent(
-            node_ip_address=services.get_node_ip_address())
+        ray_params.update_if_absent(node_ip_address=node_ip_address)
         cli_logger.labeled_value("Local node IP", ray_params.node_ip_address)
         cli_logger.old_info(logger, "Using IP address {} for this node.",
                             ray_params.node_ip_address)
@@ -462,6 +471,16 @@ def start(node_ip_address, address, port, redis_password, redis_shard_ports,
             autoscaling_config=autoscaling_config,
         )
 
+        # Fail early when starting a new cluster when one is already running
+        if address is None:
+            default_address = f"{node_ip_address}:{port}"
+            redis_addresses = services.find_redis_address(default_address)
+            if len(redis_addresses) > 0:
+                raise ConnectionError(
+                    f"Ray is already running at {default_address}. "
+                    f"Please specify a different port using the `--port`"
+                    f" command to `ray start`.")
+
         node = ray.node.Node(
             ray_params, head=True, shutdown_at_exit=block, spawn_reaper=block)
         redis_address = node.redis_address

python/ray/services.py

@@ -110,7 +110,7 @@ def new_port():
     return random.randint(10000, 65535)
 
 
-def find_redis_address_or_die():
+def find_redis_address(address=None):
     pids = psutil.pids()
     redis_addresses = set()
     for pid in pids:
@@ -129,12 +129,19 @@ def find_redis_address_or_die():
                 for arg in arglist.split(" "):
                     # TODO(ekl): Find a robust solution for locating Redis.
                     if arg.startswith("--redis-address="):
-                        addr = arg.split("=")[1]
-                        redis_addresses.add(addr)
+                        proc_addr = arg.split("=")[1]
+                        if address is not None and address != proc_addr:
+                            continue
+                        redis_addresses.add(proc_addr)
         except psutil.AccessDenied:
             pass
         except psutil.NoSuchProcess:
             pass
+    return redis_addresses
+
+
+def find_redis_address_or_die():
+    redis_addresses = find_redis_address()
     if len(redis_addresses) > 1:
         raise ConnectionError(
             f"Found multiple active Ray instances: {redis_addresses}. "

python/ray/tests/conftest.py

@@ -178,9 +178,8 @@ def ray_start_object_store_memory(request):
 @pytest.fixture
 def call_ray_start(request):
     parameter = getattr(
-        request, "param",
-        "ray start --head --num-cpus=1 --min-worker-port=0 --max-worker-port=0"
-    )
+        request, "param", "ray start --head --num-cpus=1 --min-worker-port=0 "
+        "--max-worker-port=0 --port 0")
     command_args = parameter.split(" ")
     out = ray.utils.decode(
         subprocess.check_output(command_args, stderr=subprocess.STDOUT))

python/ray/tests/test_cli.py

@@ -158,9 +158,9 @@ DEFAULT_TEST_CONFIG_PATH = str(
     reason=("Mac builds don't provide proper locale support"))
 def test_ray_start(configure_lang):
     runner = CliRunner()
-    result = runner.invoke(
-        scripts.start,
-        ["--head", "--log-style=pretty", "--log-color", "False"])
+    result = runner.invoke(scripts.start, [
+        "--head", "--log-style=pretty", "--log-color", "False", "--port", "0"
+    ])
     _die_on_error(runner.invoke(scripts.stop))
 
     _check_output_via_pattern("test_ray_start.txt", result)

python/ray/tests/test_multi_node.py

@@ -301,7 +301,7 @@ ray.get([a.log.remote(), f.remote()])
 @pytest.mark.parametrize(
     "call_ray_start", [
         "ray start --head --num-cpus=1 --num-gpus=1 " +
-        "--min-worker-port=0 --max-worker-port=0"
+        "--min-worker-port=0 --max-worker-port=0 --port 0"
     ],
     indirect=True)
 def test_drivers_release_resources(call_ray_start):
@@ -369,26 +369,24 @@ print("success")
 
 
 def test_calling_start_ray_head(call_ray_stop_only):
+
     # Test that we can call ray start with various command line
     # parameters. TODO(rkn): This test only tests the --head code path. We
     # should also test the non-head node code path.
 
-    # Test starting Ray with no arguments.
-    check_call_ray(["start", "--head"])
-    check_call_ray(["stop"])
-
     # Test starting Ray with a redis port specified.
-    check_call_ray(["start", "--head"])
+    check_call_ray(["start", "--head", "--port", "0"])
     check_call_ray(["stop"])
 
     # Test starting Ray with a node IP address specified.
-    check_call_ray(["start", "--head", "--node-ip-address", "127.0.0.1"])
+    check_call_ray(
+        ["start", "--head", "--node-ip-address", "127.0.0.1", "--port", "0"])
     check_call_ray(["stop"])
 
     # Test starting Ray with a system config parameter set.
     check_call_ray([
         "start", "--head", "--system-config",
-        "{\"metrics_report_interval_ms\":100}"
+        "{\"metrics_report_interval_ms\":100}", "--port", "0"
     ])
     check_call_ray(["stop"])
 
@@ -396,45 +394,49 @@ def test_calling_start_ray_head(call_ray_stop_only):
     # specified.
     check_call_ray([
         "start", "--head", "--object-manager-port", "12345",
-        "--node-manager-port", "54321"
+        "--node-manager-port", "54321", "--port", "0"
     ])
     check_call_ray(["stop"])
 
     # Test starting Ray with the worker port range specified.
     check_call_ray([
         "start", "--head", "--min-worker-port", "50000", "--max-worker-port",
-        "51000"
+        "51000", "--port", "0"
     ])
     check_call_ray(["stop"])
 
     # Test starting Ray with the number of CPUs specified.
-    check_call_ray(["start", "--head", "--num-cpus", "2"])
+    check_call_ray(["start", "--head", "--num-cpus", "2", "--port", "0"])
     check_call_ray(["stop"])
 
     # Test starting Ray with the number of GPUs specified.
-    check_call_ray(["start", "--head", "--num-gpus", "100"])
+    check_call_ray(["start", "--head", "--num-gpus", "100", "--port", "0"])
     check_call_ray(["stop"])
 
     # Test starting Ray with redis shard ports specified.
-    check_call_ray(
-        ["start", "--head", "--redis-shard-ports", "6380,6381,6382"])
+    check_call_ray([
+        "start", "--head", "--redis-shard-ports", "6380,6381,6382", "--port",
+        "0"
+    ])
     check_call_ray(["stop"])
 
     # Test starting Ray with all arguments specified.
     check_call_ray([
         "start", "--head", "--redis-shard-ports", "6380,6381,6382",
         "--object-manager-port", "12345", "--num-cpus", "2", "--num-gpus", "0",
-        "--resources", "{\"Custom\": 1}"
+        "--resources", "{\"Custom\": 1}", "--port", "0"
     ])
     check_call_ray(["stop"])
 
     # Test starting Ray with invalid arguments.
     with pytest.raises(subprocess.CalledProcessError):
-        check_call_ray(["start", "--head", "--address", "127.0.0.1:6379"])
+        check_call_ray(
+            ["start", "--head", "--address", "127.0.0.1:6379", "--port", "0"])
     check_call_ray(["stop"])
 
     # Test --block. Killing a child process should cause the command to exit.
-    blocked = subprocess.Popen(["ray", "start", "--head", "--block"])
+    blocked = subprocess.Popen(
+        ["ray", "start", "--head", "--block", "--port", "0"])
 
     wait_for_children_of_pid(blocked.pid, num_children=7, timeout=30)
 
@@ -447,7 +449,8 @@ def test_calling_start_ray_head(call_ray_stop_only):
     assert blocked.returncode != 0, "ray start shouldn't return 0 on bad exit"
 
     # Test --block. Killing the command should clean up all child processes.
-    blocked = subprocess.Popen(["ray", "start", "--head", "--block"])
+    blocked = subprocess.Popen(
+        ["ray", "start", "--head", "--block", "--port", "0"])
     blocked.poll()
     assert blocked.returncode is None
 

python/ray/tests/test_tempfile.py

@@ -42,7 +42,7 @@ def test_tempdir_commandline():
     shutil.rmtree(ray.utils.get_ray_temp_dir(), ignore_errors=True)
     check_call_ray([
         "start", "--head", "--temp-dir=" + os.path.join(
-            ray.utils.get_user_temp_dir(), "i_am_a_temp_dir2")
+            ray.utils.get_user_temp_dir(), "i_am_a_temp_dir2"), "--port", "0"
     ])
     assert os.path.exists(
         os.path.join(ray.utils.get_user_temp_dir(),