Support Trio with httpx (#263)

* Support Trio on httpx backend

The main limitation is that sniffing isn't supported, as the way it's currently
designed (starting a task in the background and never collecting it) is not
compatible with structured concurrency.

* Fix lint

* Add trio to develop dependencies

* Remove anyio from runtime dependencies

* Clarify asyncio/trio support

* Link to HTTPX issue in badssl tests

* Remove debug print

* Reverse asyncio/trio check per review feedback

(cherry picked from commit 33c0af3)

Author: pquentin

elastic_transport/_async_transport.py

@@ -17,6 +17,7 @@
 
 import asyncio
 import logging
+import time
 from typing import (
     Any,
     Awaitable,
@@ -30,6 +31,8 @@
     Union,
 )
 
+import sniffio
+
 from ._compat import await_if_coro
 from ._exceptions import (
     ConnectionError,
@@ -169,6 +172,7 @@ def __init__(
         # time it's needed. Gets set within '_async_call()' which should
         # precede all logic within async calls.
         self._loop: asyncio.AbstractEventLoop = None  # type: ignore[assignment]
+        self._async_library: str = None  # type: ignore[assignment]
 
         # AsyncTransport doesn't require a thread lock for
         # sniffing. Uses '_sniffing_task' instead.
@@ -258,7 +262,7 @@ async def perform_request(  # type: ignore[override, return]
             node_failure = False
             last_response: Optional[TransportApiResponse] = None
             node: BaseAsyncNode = self.node_pool.get()  # type: ignore[assignment]
-            start_time = self._loop.time()
+            start_time = time.monotonic()
             try:
                 otel_span.set_node_metadata(
                     node.host, node.port, node.base_url, target, method
@@ -277,7 +281,7 @@ async def perform_request(  # type: ignore[override, return]
                         node.base_url,
                         target,
                         resp.meta.status,
-                        self._loop.time() - start_time,
+                        time.monotonic() - start_time,
                     )
                 )
 
@@ -300,7 +304,7 @@ async def perform_request(  # type: ignore[override, return]
                         node.base_url,
                         target,
                         "N/A",
-                        self._loop.time() - start_time,
+                        time.monotonic() - start_time,
                     )
                 )
 
@@ -377,6 +381,10 @@ async def perform_request(  # type: ignore[override, return]
                     )
 
     async def sniff(self, is_initial_sniff: bool = False) -> None:  # type: ignore[override]
+        if sniffio.current_async_library() == "trio":
+            raise ValueError(
+                f"Asynchronous sniffing is not supported with the 'trio' library, got {sniffio.current_async_library}"
+            )
         await self._async_call()
         task = self._create_sniffing_task(is_initial_sniff)
 
@@ -409,8 +417,7 @@ def _should_sniff(self, is_initial_sniff: bool) -> bool:
             self._sniffing_task.result()
 
         return (
-            self._loop.time() - self._last_sniffed_at
-            >= self._min_delay_between_sniffing
+            time.monotonic() - self._last_sniffed_at >= self._min_delay_between_sniffing
         )
 
     def _create_sniffing_task(
@@ -429,7 +436,7 @@ async def _sniffing_task_impl(self, is_initial_sniff: bool) -> None:
         """Implementation of the sniffing task"""
         previously_sniffed_at = self._last_sniffed_at
         try:
-            self._last_sniffed_at = self._loop.time()
+            self._last_sniffed_at = time.monotonic()
             options = SniffOptions(
                 is_initial_sniff=is_initial_sniff, sniff_timeout=self._sniff_timeout
             )
@@ -466,8 +473,13 @@ async def _async_call(self) -> None:
         because we're not guaranteed to be within an active asyncio event loop
         when __init__() is called.
         """
-        if self._loop is not None:
+        if self._async_library is not None:
             return  # Call at most once!
+
+        self._async_library = sniffio.current_async_library()
+        if self._async_library == "trio":
+            return
+
         self._loop = asyncio.get_running_loop()
         if self._sniff_on_start:
             await self.sniff(True)

elastic_transport/_node/_http_aiohttp.py

@@ -72,7 +72,10 @@ class RequestKwarg(TypedDict, total=False):
 
 
 class AiohttpHttpNode(BaseAsyncNode):
-    """Default asynchronous node class using the ``aiohttp`` library via HTTP"""
+    """Default asynchronous node class using the ``aiohttp`` library via HTTP.
+
+    Supports asyncio.
+    """
 
     _CLIENT_META_HTTP_CLIENT = ("ai", _AIOHTTP_META_VERSION)
 

elastic_transport/_node/_http_httpx.py

@@ -46,6 +46,10 @@
 
 
 class HttpxAsyncHttpNode(BaseAsyncNode):
+    """
+    Async HTTP node using httpx. Supports both Trio and asyncio.
+    """
+
     _CLIENT_META_HTTP_CLIENT = ("hx", _HTTPX_META_VERSION)
 
     def __init__(self, config: NodeConfig):
@@ -175,11 +179,11 @@ async def perform_request(  # type: ignore[override]
                 body=body,
                 exception=err,
             )
-            raise err from None
+            raise err from e
 
         meta = ApiResponseMeta(
             resp.status_code,
-            resp.http_version,
+            resp.http_version.lstrip("HTTP/"),
             HttpHeaders(resp.headers),
             duration,
             self.config,

setup.py

@@ -52,6 +52,7 @@
     install_requires=[
         "urllib3>=1.26.2, <3",
         "certifi",
+        "sniffio",
     ],
     python_requires=">=3.8",
     extras_require={
@@ -70,6 +71,8 @@
             "opentelemetry-api",
             "opentelemetry-sdk",
             "orjson",
+            "anyio",
+            "trio",
             # Override Read the Docs default (sphinx<2)
             "sphinx>2",
             "furo",

tests/async_/test_async_transport.py

@@ -24,7 +24,9 @@
 import warnings
 from unittest import mock
 
+import anyio
 import pytest
+import sniffio
 
 from elastic_transport import (
     AiohttpHttpNode,
@@ -45,9 +47,11 @@
 from tests.conftest import AsyncDummyNode
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_async_transport_httpbin(httpbin_node_config, httpbin):
-    t = AsyncTransport([httpbin_node_config], meta_header=False)
+    t = AsyncTransport(
+        [httpbin_node_config], meta_header=False, node_class=HttpxAsyncHttpNode
+    )
     resp, data = await t.perform_request("GET", "/anything?key=value")
 
     assert resp.status == 200
@@ -57,6 +61,8 @@ async def test_async_transport_httpbin(httpbin_node_config, httpbin):
 
     data["headers"].pop("X-Amzn-Trace-Id", None)
     assert data["headers"] == {
+        "Accept": "*/*",
+        "Accept-Encoding": "gzip, deflate, br",
         "User-Agent": DEFAULT_USER_AGENT,
         "Connection": "keep-alive",
         "Host": f"{httpbin.host}:{httpbin.port}",
@@ -66,15 +72,15 @@ async def test_async_transport_httpbin(httpbin_node_config, httpbin):
 @pytest.mark.skipif(
     sys.version_info < (3, 8), reason="Mock didn't support async before Python 3.8"
 )
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_transport_close_node_pool():
     t = AsyncTransport([NodeConfig("http", "localhost", 443)])
     with mock.patch.object(t.node_pool.all()[0], "close") as node_close:
         await t.close()
     node_close.assert_called_with()
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_request_with_custom_user_agent_header():
     t = AsyncTransport(
         [NodeConfig("http", "localhost", 80)],
@@ -91,7 +97,7 @@ async def test_request_with_custom_user_agent_header():
     } == t.node_pool.get().calls[0][1]
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_body_gets_encoded_into_bytes():
     t = AsyncTransport([NodeConfig("http", "localhost", 80)], node_class=AsyncDummyNode)
 
@@ -105,7 +111,7 @@ async def test_body_gets_encoded_into_bytes():
     assert kwargs["body"] == b'{"key":"\xe4\xbd\xa0\xe5\xa5\xbd"}'
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_body_bytes_get_passed_untouched():
     t = AsyncTransport([NodeConfig("http", "localhost", 80)], node_class=AsyncDummyNode)
 
@@ -131,7 +137,7 @@ def test_kwargs_passed_on_to_node_pool():
     assert dt is t.node_pool.max_dead_node_backoff
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_request_will_fail_after_x_retries():
     t = AsyncTransport(
         [
@@ -154,7 +160,7 @@ async def test_request_will_fail_after_x_retries():
 
 
 @pytest.mark.parametrize("retry_on_timeout", [True, False])
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_retry_on_timeout(retry_on_timeout):
     t = AsyncTransport(
         [
@@ -189,7 +195,7 @@ async def test_retry_on_timeout(retry_on_timeout):
         assert len(e.value.errors) == 0
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_retry_on_status():
     t = AsyncTransport(
         [
@@ -233,7 +239,7 @@ async def test_retry_on_status():
     ]
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_failed_connection_will_be_marked_as_dead():
     t = AsyncTransport(
         [
@@ -262,7 +268,7 @@ async def test_failed_connection_will_be_marked_as_dead():
     assert all(isinstance(error, ConnectionError) for error in e.value.errors)
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_resurrected_connection_will_be_marked_as_live_on_success():
     for method in ("GET", "HEAD"):
         t = AsyncTransport(
@@ -283,7 +289,7 @@ async def test_resurrected_connection_will_be_marked_as_live_on_success():
         assert 1 == len(t.node_pool._dead_nodes.queue)
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_mark_dead_error_doesnt_raise():
     t = AsyncTransport(
         [
@@ -303,7 +309,7 @@ async def test_mark_dead_error_doesnt_raise():
     mark_dead.assert_called_with(bad_node)
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_node_class_as_string():
     t = AsyncTransport([NodeConfig("http", "localhost", 80)], node_class="aiohttp")
     assert isinstance(t.node_pool.get(), AiohttpHttpNode)
@@ -320,7 +326,7 @@ async def test_node_class_as_string():
 
 
 @pytest.mark.parametrize(["status", "boolean"], [(200, True), (299, True)])
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_head_response_true(status, boolean):
     t = AsyncTransport(
         [NodeConfig("http", "localhost", 80, _extras={"status": status, "body": b""})],
@@ -331,7 +337,7 @@ async def test_head_response_true(status, boolean):
     assert data is None
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_head_response_false():
     t = AsyncTransport(
         [NodeConfig("http", "localhost", 80, _extras={"status": 404, "body": b""})],
@@ -353,7 +359,7 @@ async def test_head_response_false():
         (HttpxAsyncHttpNode, "hx"),
     ],
 )
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_transport_client_meta_node_class(node_class, client_short_name):
     t = AsyncTransport([NodeConfig("http", "localhost", 80)], node_class=node_class)
     assert (
@@ -366,7 +372,7 @@ async def test_transport_client_meta_node_class(node_class, client_short_name):
     )
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_transport_default_client_meta_node_class():
     # Defaults to aiohttp
     t = AsyncTransport(
@@ -635,7 +641,7 @@ async def test_sniff_on_start_no_results_errors(sniff_callback):
 
 
 @pytest.mark.parametrize("pool_size", [1, 8])
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_multiple_tasks_test(pool_size):
     node_configs = [
         NodeConfig("http", "localhost", 80),
@@ -648,34 +654,43 @@ async def sniff_callback(*_):
         await asyncio.sleep(random.random())
         return node_configs
 
+    kwargs = {}
+    if sniffio.current_async_library() == "asyncio":
+        kwargs = {
+            "sniff_on_start": True,
+            "sniff_before_requests": True,
+            "sniff_on_node_failure": True,
+            "sniff_callback": sniff_callback,
+        }
+
     t = AsyncTransport(
         node_configs,
         retry_on_status=[500],
         max_retries=5,
         node_class=AsyncDummyNode,
-        sniff_on_start=True,
-        sniff_before_requests=True,
-        sniff_on_node_failure=True,
-        sniff_callback=sniff_callback,
+        **kwargs,
     )
 
-    loop = asyncio.get_running_loop()
-    start = loop.time()
+    start = time.monotonic()
+
+    successful_requests = 0
 
     async def run_requests():
-        successful_requests = 0
-        while loop.time() - start < 2:
+        nonlocal successful_requests
+        while time.monotonic() - start < 2:
             await t.perform_request("GET", "/")
             successful_requests += 1
         return successful_requests
 
-    tasks = [loop.create_task(run_requests()) for _ in range(pool_size * 2)]
-    assert sum([await task for task in tasks]) >= 1000
+    async with anyio.create_task_group() as tg:
+        for _ in range(pool_size * 2):
+            tg.start_soon(run_requests)
+    assert successful_requests >= 1000
 
 
-@pytest.mark.asyncio
+@pytest.mark.anyio
 async def test_httpbin(httpbin_node_config):
-    t = AsyncTransport([httpbin_node_config])
+    t = AsyncTransport([httpbin_node_config], node_class=HttpxAsyncHttpNode)
     resp = await t.perform_request("GET", "/anything")
     assert resp.meta.status == 200
     assert isinstance(resp.body, dict)