feat: Add support for NO_PROXY for websocket connections

src/prefect/events/clients.py

@@ -16,6 +16,7 @@
     cast,
 )
 from urllib.parse import urlparse
+from urllib.request import proxy_bypass
 from uuid import UUID
 
 import orjson
@@ -95,6 +96,9 @@ def __init__(self: Self, uri: str, **kwargs: Any):
         u = urlparse(uri)
         host = u.hostname
 
+        if not host:
+            raise ValueError(f"Invalid URI {uri}, no hostname found")
+
         if u.scheme == "ws":
             port = u.port or 80
             proxy_url = os.environ.get("HTTP_PROXY")
@@ -107,7 +111,9 @@ def __init__(self: Self, uri: str, **kwargs: Any):
                 "Unsupported scheme %s. Expected 'ws' or 'wss'. " % u.scheme
             )
 
-        self._proxy = Proxy.from_url(proxy_url) if proxy_url else None
+        self._proxy = (
+            Proxy.from_url(proxy_url) if proxy_url and not proxy_bypass(host) else None
+        )
         self._host = host
         self._port = port
 

tests/utilities/test_proxy.py

@@ -1,5 +1,7 @@
 from unittest.mock import Mock
 
+import pytest
+
 from prefect.events.clients import WebsocketProxyConnect
 
 
@@ -32,11 +34,41 @@ def test_init_ws_with_proxy(monkeypatch):
 
 
 def test_init_wss_with_proxy(monkeypatch):
-    monkeypatch.setenv("HTTPS_PROXY", "https://proxy:3128")
+    monkeypatch.setenv("HTTPS_PROXY", "http://proxy:3128")
     mock_proxy = Mock()
     monkeypatch.setattr("prefect.events.clients.Proxy", mock_proxy)
 
     client = WebsocketProxyConnect("wss://example.com")
 
-    mock_proxy.from_url.assert_called_once_with("https://proxy:3128")
+    mock_proxy.from_url.assert_called_once_with("http://proxy:3128")
     assert client._proxy is not None
+
+
+@pytest.mark.parametrize(
+    "no_proxy", ["example.com", ".com", "example.com,example2.com"]
+)
+def test_init_ws_with_no_proxy(monkeypatch, no_proxy: str):
+    # Validate http proxy is set
+    monkeypatch.setenv("HTTP_PROXY", "http://proxy:3128")
+    client = WebsocketProxyConnect("ws://example.com")
+    assert client._proxy is not None
+
+    # Keeping existing proxy configuration, validate we can disable it with NO_PROXY
+    monkeypatch.setenv("NO_PROXY", no_proxy)
+    client = WebsocketProxyConnect("ws://example.com")
+    assert client._proxy is None
+
+
+@pytest.mark.parametrize(
+    "no_proxy", ["example.com", ".com", "example.com,example2.com"]
+)
+def test_init_wss_with_no_proxy(monkeypatch, no_proxy: str):
+    # Validate https proxy is set
+    monkeypatch.setenv("HTTPS_PROXY", "http://proxy:3128")
+    client = WebsocketProxyConnect("wss://example.com")
+    assert client._proxy is not None
+
+    # Keeping existing proxy configuration, validate we can disable it with NO_PROXY
+    monkeypatch.setenv("NO_PROXY", no_proxy)
+    client = WebsocketProxyConnect("wss://example.com")
+    assert client._proxy is None