cohere[patch]: Allow overriding of the base URL in Cohere Client (#19766)

This PR adds the ability for a user to override the base API url for the
Cohere client for embeddings and chat llm.

libs/partners/cohere/langchain_cohere/embeddings.py

@@ -45,6 +45,9 @@ class CohereEmbeddings(BaseModel, Embeddings):
     user_agent: str = "langchain"
     """Identifier for the application making the request."""
 
+    base_url: Optional[str] = None
+    """Override the default Cohere API URL."""
+
     class Config:
         """Configuration for this pydantic object."""
 
@@ -64,11 +67,13 @@ class CohereEmbeddings(BaseModel, Embeddings):
             cohere_api_key,
             timeout=request_timeout,
             client_name=client_name,
+            base_url=values["base_url"],
         )
         values["async_client"] = cohere.AsyncClient(
             cohere_api_key,
             timeout=request_timeout,
             client_name=client_name,
+            base_url=values["base_url"],
         )
 
         return values

libs/partners/cohere/langchain_cohere/llms.py

@@ -69,6 +69,9 @@ class BaseCohere(Serializable):
     user_agent: str = "langchain"
     """Identifier for the application making the request."""
 
+    base_url: Optional[str] = None
+    """Override the default Cohere API URL."""
+
     @root_validator()
     def validate_environment(cls, values: Dict) -> Dict:
         """Validate that api key and python package exists in environment."""
@@ -79,10 +82,12 @@ class BaseCohere(Serializable):
         values["client"] = cohere.Client(
             api_key=values["cohere_api_key"].get_secret_value(),
             client_name=client_name,
+            base_url=values["base_url"],
         )
         values["async_client"] = cohere.AsyncClient(
             api_key=values["cohere_api_key"].get_secret_value(),
             client_name=client_name,
+            base_url=values["base_url"],
         )
         return values