Support locally served models which do not require an api key (#814)

Co-authored-by: JONEMI21 <[email protected]>
Co-authored-by: Samuel Colvin <[email protected]>

Author: mikeedjones

pydantic_ai_slim/pydantic_ai/models/openai.py

@@ -1,5 +1,6 @@
 from __future__ import annotations as _annotations
 
+import os
 from collections.abc import AsyncIterable, AsyncIterator, Iterable
 from contextlib import asynccontextmanager
 from dataclasses import dataclass, field
@@ -101,7 +102,11 @@ def __init__(
                 In the future, this may be inferred from the model name.
         """
         self.model_name: OpenAIModelName = model_name
-        if openai_client is not None:
+        # This is a workaround for the OpenAI client requiring an API key, whilst locally served,
+        # openai compatible models do not always need an API key.
+        if api_key is None and 'OPENAI_API_KEY' not in os.environ and base_url is not None and openai_client is None:
+            api_key = ''
+        elif openai_client is not None:
             assert http_client is None, 'Cannot provide both `openai_client` and `http_client`'
             assert base_url is None, 'Cannot provide both `openai_client` and `base_url`'
             assert api_key is None, 'Cannot provide both `openai_client` and `api_key`'

tests/models/test_openai.py

@@ -29,7 +29,7 @@
 from .mock_async_stream import MockAsyncStream
 
 with try_import() as imports_successful:
-    from openai import NOT_GIVEN, AsyncOpenAI
+    from openai import NOT_GIVEN, AsyncOpenAI, OpenAIError
     from openai.types import chat
     from openai.types.chat.chat_completion import Choice
     from openai.types.chat.chat_completion_chunk import (
@@ -65,6 +65,19 @@ def test_init_with_base_url():
     m.name()
 
 
+def test_init_with_non_openai_model():
+    m = OpenAIModel('llama3.2-vision:latest', base_url='https://example.com/v1/')
+    m.name()
+
+
+def test_init_of_openai_without_api_key_raises_error():
+    with pytest.raises(
+        OpenAIError,
+        match='^The api_key client option must be set either by passing api_key to the client or by setting the OPENAI_API_KEY environment variable$',
+    ):
+        OpenAIModel('gpt-4o')
+
+
 @dataclass
 class MockOpenAI:
     completions: chat.ChatCompletion | list[chat.ChatCompletion] | None = None