Wait for the Dapr health check asynchronously in aio/clients/grpc/subscription.py to avoid blocking, ensuring the asyncio gRPC stream can close properly.

dapr/aio/clients/grpc/client.py

@@ -1912,7 +1912,7 @@ async def wait(self, timeout_s: float):
                     remaining = (start + timeout_s) - time.time()
                     if remaining < 0:
                         raise e
-                    asyncio.sleep(min(1, remaining))
+                    await asyncio.sleep(min(1, remaining))
 
     async def get_metadata(self) -> GetMetadataResponse:
         """Returns information about the sidecar allowing for runtime

dapr/aio/clients/grpc/subscription.py

@@ -3,7 +3,7 @@
 from grpc.aio import AioRpcError
 
 from dapr.clients.grpc._response import TopicEventResponse
-from dapr.clients.health import DaprHealth
+from dapr.aio.clients.health import DaprHealth
 from dapr.common.pubsub.subscription import (
     StreamInactiveError,
     SubscriptionMessage,
@@ -51,7 +51,7 @@ async def outgoing_request_iterator():
 
     async def reconnect_stream(self):
         await self.close()
-        DaprHealth.wait_for_sidecar()
+        await DaprHealth.wait_until_ready()
         print('Attempting to reconnect...')
         await self.start()
 
@@ -66,7 +66,7 @@ async def next_message(self):
                     return None
                 return SubscriptionMessage(message.event_message)
         except AioRpcError as e:
-            if e.code() == StatusCode.UNAVAILABLE:
+            if e.code() == StatusCode.UNAVAILABLE or e.code() == StatusCode.UNKNOWN:
                 print(
                     f'gRPC error while reading from stream: {e.details()}, '
                     f'Status Code: {e.code()}. '

dapr/aio/clients/health.py

@@ -0,0 +1,55 @@
+# -*- coding: utf-8 -*-
+
+"""
+Copyright 2024 The Dapr Authors
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+"""
+import asyncio
+import urllib.request
+import urllib.error
+import time
+
+from dapr.clients.http.conf import DAPR_API_TOKEN_HEADER, USER_AGENT_HEADER, DAPR_USER_AGENT
+from dapr.clients.http.helpers import get_api_url
+from dapr.conf import settings
+
+
+class DaprHealth:
+    @staticmethod
+    async def wait_until_ready():
+        health_url = f'{get_api_url()}/healthz/outbound'
+        headers = {USER_AGENT_HEADER: DAPR_USER_AGENT}
+        if settings.DAPR_API_TOKEN is not None:
+            headers[DAPR_API_TOKEN_HEADER] = settings.DAPR_API_TOKEN
+        timeout = float(settings.DAPR_HEALTH_TIMEOUT)
+
+        start = time.time()
+        while True:
+            try:
+                req = urllib.request.Request(health_url, headers=headers)
+                with urllib.request.urlopen(req, context=DaprHealth.get_ssl_context()) as response:
+                    if 200 <= response.status < 300:
+                        break
+            except urllib.error.URLError as e:
+                print(f'Health check on {health_url} failed: {e.reason}')
+            except Exception as e:
+                print(f'Unexpected error during health check: {e}')
+
+            remaining = (start + timeout) - time.time()
+            if remaining <= 0:
+                raise TimeoutError(f'Dapr health check timed out, after {timeout}.')
+            await asyncio.sleep(min(1.0, remaining))
+
+    @staticmethod
+    def get_ssl_context():
+        # This method is used (overwritten) from tests
+        # to return context for self-signed certificates
+        return None

tests/clients/test_dapr_grpc_client_async_secure.py

@@ -18,14 +18,16 @@
 from unittest.mock import patch
 
 from dapr.aio.clients.grpc.client import DaprGrpcClientAsync
-from dapr.clients.health import DaprHealth
+from dapr.aio.clients.health import DaprHealth as DaprHealthAsync
+from dapr.clients.health import DaprHealth as DaprHealth
 from tests.clients.certs import replacement_get_credentials_func, replacement_get_health_context
 from tests.clients.test_dapr_grpc_client_async import DaprGrpcClientAsyncTests
 from .fake_dapr_server import FakeDaprSidecar
 from dapr.conf import settings
 
 
 DaprGrpcClientAsync.get_credentials = replacement_get_credentials_func
+DaprHealthAsync.get_ssl_context = replacement_get_health_context
 DaprHealth.get_ssl_context = replacement_get_health_context
 
 

tests/clients/test_healthcheck_async.py

@@ -0,0 +1,181 @@
+# -*- coding: utf-8 -*-
+
+"""
+Copyright 2025 The Dapr Authors
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+"""
+import asyncio
+import time
+import unittest
+from unittest.mock import patch, MagicMock
+
+from dapr.aio.clients.health import DaprHealth
+from dapr.conf import settings
+from dapr.version import __version__
+
+
+class DaprHealthCheckAsyncTests(unittest.IsolatedAsyncioTestCase):
+    @patch.object(settings, 'DAPR_HTTP_ENDPOINT', 'http://domain.com:3500')
+    @patch('urllib.request.urlopen')
+    async def test_wait_until_ready_success(self, mock_urlopen):
+        mock_urlopen.return_value.__enter__.return_value = MagicMock(status=200)
+
+        try:
+            await DaprHealth.wait_until_ready()
+        except Exception as e:
+            self.fail(f'wait_until_ready() raised an exception unexpectedly: {e}')
+
+        mock_urlopen.assert_called_once()
+
+        called_url = mock_urlopen.call_args[0][0].full_url
+        self.assertEqual(called_url, 'http://domain.com:3500/v1.0/healthz/outbound')
+
+        # Check headers are properly set
+        headers = mock_urlopen.call_args[0][0].headers
+        self.assertIn('User-agent', headers)
+        self.assertEqual(headers['User-agent'], f'dapr-sdk-python/{__version__}')
+
+    @patch.object(settings, 'DAPR_HTTP_ENDPOINT', 'http://domain.com:3500')
+    @patch.object(settings, 'DAPR_API_TOKEN', 'mytoken')
+    @patch('urllib.request.urlopen')
+    async def test_wait_until_ready_success_with_api_token(self, mock_urlopen):
+        mock_urlopen.return_value.__enter__.return_value = MagicMock(status=200)
+
+        try:
+            await DaprHealth.wait_until_ready()
+        except Exception as e:
+            self.fail(f'wait_until_ready() raised an exception unexpectedly: {e}')
+
+        mock_urlopen.assert_called_once()
+
+        # Check headers are properly set
+        headers = mock_urlopen.call_args[0][0].headers
+        self.assertIn('User-agent', headers)
+        self.assertEqual(headers['User-agent'], f'dapr-sdk-python/{__version__}')
+        self.assertIn('Dapr-api-token', headers)
+        self.assertEqual(headers['Dapr-api-token'], 'mytoken')
+
+    @patch.object(settings, 'DAPR_HEALTH_TIMEOUT', '2.5')
+    @patch('urllib.request.urlopen')
+    async def test_wait_until_ready_timeout(self, mock_urlopen):
+        mock_urlopen.return_value.__enter__.return_value = MagicMock(status=500)
+
+        start = time.time()
+
+        with self.assertRaises(TimeoutError):
+            await DaprHealth.wait_until_ready()
+
+        self.assertGreaterEqual(time.time() - start, 2.5)
+        self.assertGreater(mock_urlopen.call_count, 1)
+
+    @patch.object(settings, 'DAPR_HTTP_ENDPOINT', 'http://domain.com:3500')
+    @patch.object(settings, 'DAPR_HEALTH_TIMEOUT', '5.0')
+    @patch('urllib.request.urlopen')
+    async def test_health_check_does_not_block(self, mock_urlopen):
+        """Test that health check doesn't block other async tasks from running"""
+        # Mock health check to retry several times before succeeding
+        call_count = [0]  # Use list to allow modification in nested function
+
+        class MockResponse:
+            def __init__(self, status):
+                self.status = status
+
+            def __enter__(self):
+                return self
+
+            def __exit__(self, exc_type, exc_val, exc_tb):
+                return None
+
+        def side_effect(*args, **kwargs):
+            call_count[0] += 1
+            # First 2 calls fail with URLError, then succeed
+            # This will cause ~2 seconds of retries (1 second sleep after each failure)
+            if call_count[0] <= 2:
+                import urllib.error
+
+                raise urllib.error.URLError('Connection refused')
+            else:
+                return MockResponse(status=200)
+
+        mock_urlopen.side_effect = side_effect
+
+        # Counter that will be incremented by background task
+        counter = [0]  # Use list to allow modification in nested function
+        is_running = [True]
+
+        async def increment_counter():
+            """Background task that increments counter every 0.5 seconds"""
+            while is_running[0]:
+                await asyncio.sleep(0.5)
+                counter[0] += 1
+
+        # Start the background task
+        counter_task = asyncio.create_task(increment_counter())
+
+        try:
+            # Run health check (will take ~2 seconds with retries)
+            await DaprHealth.wait_until_ready()
+
+            # Stop the background task
+            is_running[0] = False
+            await asyncio.sleep(0.1)  # Give it time to finish current iteration
+
+            # Verify the counter was incremented during health check
+            # In 2 seconds with 0.5s intervals, we expect at least 3 increments
+            self.assertGreaterEqual(
+                counter[0],
+                3,
+                f'Expected counter to increment at least 3 times during health check, '
+                f'but got {counter[0]}. This indicates health check may be blocking.',
+            )
+
+            # Verify health check made multiple attempts
+            self.assertGreaterEqual(call_count[0], 2)
+
+        finally:
+            # Clean up
+            is_running[0] = False
+            counter_task.cancel()
+            try:
+                await counter_task
+            except asyncio.CancelledError:
+                pass
+
+    @patch.object(settings, 'DAPR_HTTP_ENDPOINT', 'http://domain.com:3500')
+    @patch('urllib.request.urlopen')
+    async def test_multiple_health_checks_concurrent(self, mock_urlopen):
+        """Test that multiple health check calls can run concurrently"""
+        mock_urlopen.return_value.__enter__.return_value = MagicMock(status=200)
+
+        # Run multiple health checks concurrently
+        start_time = time.time()
+        results = await asyncio.gather(
+            DaprHealth.wait_until_ready(),
+            DaprHealth.wait_until_ready(),
+            DaprHealth.wait_until_ready(),
+        )
+        elapsed = time.time() - start_time
+
+        # All should complete successfully
+        self.assertEqual(len(results), 3)
+        self.assertIsNone(results[0])
+        self.assertIsNone(results[1])
+        self.assertIsNone(results[2])
+
+        # Should complete quickly since they run concurrently
+        self.assertLess(elapsed, 1.0)
+
+        # Verify multiple calls were made
+        self.assertGreaterEqual(mock_urlopen.call_count, 3)
+
+
+if __name__ == '__main__':
+    unittest.main()