fix(anthropic): Add proxy (#32409)

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fix #30146
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---------

Co-authored-by: Mason Daugherty <mason@langchain.dev>
Co-authored-by: Mason Daugherty <github@mdrxy.com>

libs/partners/anthropic/langchain_anthropic/_client_utils.py

@@ -50,6 +50,7 @@ def _get_default_httpx_client(
     *,
     base_url: Optional[str],
     timeout: Any = _NOT_GIVEN,
+    anthropic_proxy: Optional[str] = None,
 ) -> _SyncHttpxClientWrapper:
     kwargs: dict[str, Any] = {
         "base_url": base_url
@@ -58,6 +59,8 @@ def _get_default_httpx_client(
     }
     if timeout is not _NOT_GIVEN:
         kwargs["timeout"] = timeout
+    if anthropic_proxy is not None:
+        kwargs["proxy"] = anthropic_proxy
     return _SyncHttpxClientWrapper(**kwargs)
 
 
@@ -66,6 +69,7 @@ def _get_default_async_httpx_client(
     *,
     base_url: Optional[str],
     timeout: Any = _NOT_GIVEN,
+    anthropic_proxy: Optional[str] = None,
 ) -> _AsyncHttpxClientWrapper:
     kwargs: dict[str, Any] = {
         "base_url": base_url
@@ -74,4 +78,6 @@ def _get_default_async_httpx_client(
     }
     if timeout is not _NOT_GIVEN:
         kwargs["timeout"] = timeout
+    if anthropic_proxy is not None:
+        kwargs["proxy"] = anthropic_proxy
     return _AsyncHttpxClientWrapper(**kwargs)

libs/partners/anthropic/langchain_anthropic/chat_models.py

@@ -502,6 +502,9 @@ class ChatAnthropic(BaseChatModel):
     Key init args — client params:
         timeout: Optional[float]
             Timeout for requests.
+        anthropic_proxy: Optional[str]
+            Proxy to use for the Anthropic clients, will be used for every API call.
+            If not passed in will be read from env var ``ANTHROPIC_PROXY``.
         max_retries: int
             Max number of retries if a request fails.
         api_key: Optional[str]
@@ -1245,6 +1248,14 @@ class ChatAnthropic(BaseChatModel):
     )
     """Automatically read from env var ``ANTHROPIC_API_KEY`` if not provided."""
 
+    anthropic_proxy: Optional[str] = Field(
+        default_factory=from_env("ANTHROPIC_PROXY", default=None)
+    )
+    """Proxy to use for the Anthropic clients, will be used for every API call.
+
+    If not provided, will attempt to read from the ``ANTHROPIC_PROXY`` environment
+    variable."""
+
     default_headers: Optional[Mapping[str, str]] = None
     """Headers to pass to the Anthropic clients, will be used for every API call."""
 
@@ -1360,6 +1371,8 @@ class ChatAnthropic(BaseChatModel):
         http_client_params = {"base_url": client_params["base_url"]}
         if "timeout" in client_params:
             http_client_params["timeout"] = client_params["timeout"]
+        if self.anthropic_proxy:
+            http_client_params["anthropic_proxy"] = self.anthropic_proxy
         http_client = _get_default_httpx_client(**http_client_params)
         params = {
             **client_params,
@@ -1373,6 +1386,8 @@ class ChatAnthropic(BaseChatModel):
         http_client_params = {"base_url": client_params["base_url"]}
         if "timeout" in client_params:
             http_client_params["timeout"] = client_params["timeout"]
+        if self.anthropic_proxy:
+            http_client_params["anthropic_proxy"] = self.anthropic_proxy
         http_client = _get_default_async_httpx_client(**http_client_params)
         params = {
             **client_params,

libs/partners/anthropic/tests/unit_tests/test_chat_models.py

@@ -62,6 +62,55 @@ def test_anthropic_client_caching() -> None:
     assert llm1._client._client is not llm5._client._client
 
 
+def test_anthropic_proxy_support() -> None:
+    """Test that both sync and async clients support proxy configuration."""
+    proxy_url = "http://proxy.example.com:8080"
+
+    # Test sync client with proxy
+    llm_sync = ChatAnthropic(
+        model="claude-3-5-sonnet-latest", anthropic_proxy=proxy_url
+    )
+    sync_client = llm_sync._client
+    assert sync_client is not None
+
+    # Test async client with proxy - this should not raise TypeError
+    async_client = llm_sync._async_client
+    assert async_client is not None
+
+    # Test that clients with different proxy settings are not cached together
+    llm_no_proxy = ChatAnthropic(model="claude-3-5-sonnet-latest")
+    llm_with_proxy = ChatAnthropic(
+        model="claude-3-5-sonnet-latest", anthropic_proxy=proxy_url
+    )
+
+    # Different proxy settings should result in different cached clients
+    assert llm_no_proxy._client._client is not llm_with_proxy._client._client
+
+
+def test_anthropic_proxy_from_environment() -> None:
+    """Test that proxy can be set from ANTHROPIC_PROXY environment variable."""
+    proxy_url = "http://env-proxy.example.com:8080"
+
+    # Test with environment variable set
+    with patch.dict(os.environ, {"ANTHROPIC_PROXY": proxy_url}):
+        llm = ChatAnthropic(model="claude-3-5-sonnet-latest")
+        assert llm.anthropic_proxy == proxy_url
+
+        # Should be able to create clients successfully
+        sync_client = llm._client
+        async_client = llm._async_client
+        assert sync_client is not None
+        assert async_client is not None
+
+    # Test that explicit parameter overrides environment variable
+    with patch.dict(os.environ, {"ANTHROPIC_PROXY": "http://env-proxy.com"}):
+        explicit_proxy = "http://explicit-proxy.com"
+        llm = ChatAnthropic(
+            model="claude-3-5-sonnet-latest", anthropic_proxy=explicit_proxy
+        )
+        assert llm.anthropic_proxy == explicit_proxy
+
+
 @pytest.mark.requires("anthropic")
 def test_anthropic_model_name_param() -> None:
     llm = ChatAnthropic(model_name="foo")  # type: ignore[call-arg, call-arg]

libs/partners/anthropic/tests/unit_tests/test_client_utils.py

@@ -0,0 +1,62 @@
+"""Test client utility functions."""
+
+from __future__ import annotations
+
+from langchain_anthropic._client_utils import (
+    _get_default_async_httpx_client,
+    _get_default_httpx_client,
+)
+
+
+def test_sync_client_without_proxy() -> None:
+    """Test sync client creation without proxy."""
+    client = _get_default_httpx_client(base_url="https://api.anthropic.com")
+
+    # Should not have proxy configured
+    assert not hasattr(client, "proxies") or client.proxies is None
+
+
+def test_sync_client_with_proxy() -> None:
+    """Test sync client creation with proxy."""
+    proxy_url = "http://proxy.example.com:8080"
+    client = _get_default_httpx_client(
+        base_url="https://api.anthropic.com", anthropic_proxy=proxy_url
+    )
+
+    # Check internal _transport since httpx stores proxy configuration in the transport
+    # layer
+    transport = getattr(client, "_transport", None)
+    assert transport is not None
+
+
+def test_async_client_without_proxy() -> None:
+    """Test async client creation without proxy."""
+    client = _get_default_async_httpx_client(base_url="https://api.anthropic.com")
+
+    assert not hasattr(client, "proxies") or client.proxies is None
+
+
+def test_async_client_with_proxy() -> None:
+    """Test async client creation with proxy."""
+    proxy_url = "http://proxy.example.com:8080"
+    client = _get_default_async_httpx_client(
+        base_url="https://api.anthropic.com", anthropic_proxy=proxy_url
+    )
+
+    transport = getattr(client, "_transport", None)
+    assert transport is not None
+
+
+def test_client_proxy_none_value() -> None:
+    """Test that explicitly passing None for proxy works correctly."""
+    sync_client = _get_default_httpx_client(
+        base_url="https://api.anthropic.com", anthropic_proxy=None
+    )
+
+    async_client = _get_default_async_httpx_client(
+        base_url="https://api.anthropic.com", anthropic_proxy=None
+    )
+
+    # Both should be created successfully with None proxy
+    assert sync_client is not None
+    assert async_client is not None