Support setting OpenAI params using environment variables (#12)

README.md

@@ -219,6 +219,20 @@ for hero in create_superhero_team("The Food Dudes"):
 - The `Annotated` type annotation can be used to provide descriptions and other metadata for function parameters. See [the pydantic documentation on using `Field` to describe function arguments](https://docs.pydantic.dev/latest/usage/validation_decorator/#using-field-to-describe-function-arguments).
 - The `@prompt` and `@prompt_chain` decorators also accept a `model` argument. You can pass an instance of `OpenaiChatModel` (from `magentic.chat_model.openai_chat_model`) to use GPT4 or configure a different temperature.
 
+## Configuration
+
+The order of precedence of configuration is
+
+1. Arguments passed when initializing an instance in Python
+2. Environment variables
+
+The following environment variables can be set.
+
+| Environment Variable        | Description               |
+| --------------------------- | ------------------------- |
+| MAGENTIC_OPENAI_MODEL       | OpenAI model e.g. "gpt-4" |
+| MAGENTIC_OPENAI_TEMPERATURE | OpenAI temperature, float |
+
 ## Type Checking
 
 Many type checkers will raise warnings or errors for functions with the `@prompt` decorator due to the function having no body or return value. There are several ways to deal with these.

pyproject.toml

@@ -27,6 +27,7 @@ repository = "https://github.com/jackmpcollins/magentic"
 python = ">=3.10"
 openai = ">=0.27"
 pydantic = ">=2.0.0"
+pydantic-settings = ">=2.0.0"
 
 [tool.poetry.group.dev.dependencies]
 black = "*"

src/magentic/chat_model/openai_chat_model.py

@@ -17,6 +17,7 @@
     UserMessage,
 )
 from magentic.function_call import FunctionCall
+from magentic.settings import get_settings
 from magentic.streaming import (
     AsyncStreamedStr,
     StreamedStr,
@@ -435,10 +436,22 @@ async def openai_chatcompletion_acreate(
 
 
 class OpenaiChatModel:
-    def __init__(self, model: str = "gpt-3.5-turbo-0613", temperature: float = 0):
+    def __init__(self, model: str | None = None, temperature: float | None = None):
         self._model = model
         self._temperature = temperature
 
+    @property
+    def model(self) -> str:
+        if self._model is not None:
+            return self._model
+        return get_settings().openai_model
+
+    @property
+    def temperature(self) -> float | None:
+        if self._temperature is not None:
+            return self._temperature
+        return get_settings().openai_temperature
+
     def complete(
         self,
         messages: Iterable[Message[Any]],
@@ -463,9 +476,9 @@ def complete(
 
         openai_functions = [schema.dict() for schema in function_schemas]
         response = openai_chatcompletion_create(
-            model=self._model,
+            model=self.model,
             messages=[message_to_openai_message(m) for m in messages],
-            temperature=self._temperature,
+            temperature=self.temperature,
             functions=openai_functions,
             function_call=(
                 {"name": openai_functions[0]["name"]}
@@ -536,9 +549,9 @@ async def acomplete(
 
         openai_functions = [schema.dict() for schema in function_schemas]
         response = await openai_chatcompletion_acreate(
-            model=self._model,
+            model=self.model,
             messages=[message_to_openai_message(m) for m in messages],
-            temperature=self._temperature,
+            temperature=self.temperature,
             functions=openai_functions,
             function_call=(
                 {"name": openai_functions[0]["name"]}

src/magentic/settings.py

@@ -0,0 +1,12 @@
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class Settings(BaseSettings):
+    model_config = SettingsConfigDict(env_prefix="MAGENTIC_")
+
+    openai_model: str = "gpt-3.5-turbo"
+    openai_temperature: float | None = None
+
+
+def get_settings() -> Settings:
+    return Settings()

tests/test_openai_chat_model.py

@@ -14,6 +14,7 @@
     DictFunctionSchema,
     FunctionCallFunctionSchema,
     IterableFunctionSchema,
+    OpenaiChatModel,
 )
 from magentic.function_call import FunctionCall
 from magentic.streaming import async_iter
@@ -605,3 +606,13 @@ def test_function_call_function_schema_serialize_args(
 ):
     serialized_args = FunctionCallFunctionSchema(function).serialize_args(args)
     assert json.loads(serialized_args) == json.loads(expected_args_str)
+
+
+def test_openai_chat_model_model(monkeypatch):
+    monkeypatch.setenv("MAGENTIC_OPENAI_MODEL", "gpt-4")
+    assert OpenaiChatModel().model == "gpt-4"
+
+
+def test_openai_chat_model_temperature(monkeypatch):
+    monkeypatch.setenv("MAGENTIC_OPENAI_TEMPERATURE", "2")
+    assert OpenaiChatModel().temperature == 2