Add openai.api_base to support openapi proxy (#2823)

I need access openai api through a proxy, so to add openai.api_base to
support this method.

Co-authored-by: bijia <bijia1@xiaomi.com>

langchain/llms/openai.py

@@ -151,6 +151,7 @@ class BaseOpenAI(BaseLLM):
     model_kwargs: Dict[str, Any] = Field(default_factory=dict)
     """Holds any model parameters valid for `create` call not explicitly specified."""
     openai_api_key: Optional[str] = None
+    openai_api_base: Optional[str] = None
     openai_organization: Optional[str] = None
     batch_size: int = 20
     """Batch size to use when passing multiple documents to generate."""
@@ -205,6 +206,12 @@ class BaseOpenAI(BaseLLM):
         openai_api_key = get_from_dict_or_env(
             values, "openai_api_key", "OPENAI_API_KEY"
         )
+        openai_api_base = get_from_dict_or_env(
+            values,
+            "openai_api_base",
+            "OPENAI_API_BASE",
+            default="",
+        )
         openai_organization = get_from_dict_or_env(
             values,
             "openai_organization",
@@ -215,6 +222,10 @@ class BaseOpenAI(BaseLLM):
             import openai
 
             openai.api_key = openai_api_key
+            if openai_api_base:
+                print("USING API_BASE: ")
+                print(openai_api_base)
+                openai.api_base = openai_api_base
             if openai_organization:
                 print("USING ORGANIZATION: ")
                 print(openai_organization)
@@ -567,6 +578,7 @@ class OpenAIChat(BaseLLM):
     model_kwargs: Dict[str, Any] = Field(default_factory=dict)
     """Holds any model parameters valid for `create` call not explicitly specified."""
     openai_api_key: Optional[str] = None
+    openai_api_base: Optional[str] = None
     max_retries: int = 6
     """Maximum number of retries to make when generating."""
     prefix_messages: List = Field(default_factory=list)
@@ -599,6 +611,12 @@ class OpenAIChat(BaseLLM):
         openai_api_key = get_from_dict_or_env(
             values, "openai_api_key", "OPENAI_API_KEY"
         )
+        openai_api_base = get_from_dict_or_env(
+            values,
+            "openai_api_base",
+            "OPENAI_API_BASE",
+            default="",
+        )
         openai_organization = get_from_dict_or_env(
             values, "openai_organization", "OPENAI_ORGANIZATION", default=""
         )
@@ -606,6 +624,8 @@ class OpenAIChat(BaseLLM):
             import openai
 
             openai.api_key = openai_api_key
+            if openai_api_base:
+                openai.api_base = openai_api_base
             if openai_organization:
                 openai.organization = openai_organization
         except ImportError: