[Feature] Open AI Client Mixin (#779)

## Changes
Add Open AI Client Mixing with the Serving Endpoints API. Open AI Client
requires a token to be authenticated. Therefore we are moving the
creation of OpenAI client to the databricks sdk so that users can easily
use it in both the notebook and model serving environments

## Tests
Dogfood Test:
https://e2-dogfood.staging.cloud.databricks.com/editor/notebooks/2337940012762945?o=6051921418418893

- [x] `make test` run locally
- [x] `make fmt` applied
- [ ] relevant integration tests applied

---------

Signed-off-by: aravind-segu <[email protected]>

Author: aravind-segu

.codegen/__init__.py.tmpl

@@ -5,6 +5,7 @@ from databricks.sdk.credentials_provider import CredentialsStrategy
 from databricks.sdk.mixins.files import DbfsExt
 from databricks.sdk.mixins.compute import ClustersExt
 from databricks.sdk.mixins.workspace import WorkspaceExt
+from databricks.sdk.mixins.open_ai_client import ServingEndpointsExt
 {{- range .Services}}
 from databricks.sdk.service.{{.Package.Name}} import {{.PascalName}}API{{end}}
 from databricks.sdk.service.provisioning import Workspace
@@ -17,7 +18,7 @@ from typing import Optional
   "google_credentials" "google_service_account" }}
 
 {{- define "api" -}}
-  {{- $mixins := dict "ClustersAPI" "ClustersExt" "DbfsAPI" "DbfsExt" "WorkspaceAPI" "WorkspaceExt" -}}
+  {{- $mixins := dict "ClustersAPI" "ClustersExt" "DbfsAPI" "DbfsExt" "WorkspaceAPI" "WorkspaceExt" "ServingEndpointsExt" "ServingEndpointsApi" -}}
   {{- $genApi := concat .PascalName "API" -}}
   {{- getOrDefault $mixins $genApi $genApi -}}
 {{- end -}}

NOTICE

@@ -12,8 +12,22 @@ googleapis/google-auth-library-python - https://github.com/googleapis/google-aut
 Copyright google-auth-library-python authors
 License - https://github.com/googleapis/google-auth-library-python/blob/main/LICENSE
 
+openai/openai-python - https://github.com/openai/openai-python
+Copyright 2024 OpenAI
+License - https://github.com/openai/openai-python/blob/main/LICENSE
+
 This software contains code from the following open source projects, licensed under the BSD (3-clause) license.
 
 x/oauth2 - https://cs.opensource.google/go/x/oauth2/+/master:oauth2.go
 Copyright 2014 The Go Authors. All rights reserved.
 License - https://cs.opensource.google/go/x/oauth2/+/master:LICENSE
+
+encode/httpx - https://github.com/encode/httpx
+Copyright 2019, Encode OSS Ltd
+License - https://github.com/encode/httpx/blob/master/LICENSE.md
+
+This software contains code from the following open source projects, licensed under the MIT license:
+
+langchain-ai/langchain - https://github.com/langchain-ai/langchain/blob/master/libs/partners/openai
+Copyright 2023 LangChain, Inc.
+License - https://github.com/langchain-ai/langchain/blob/master/libs/partners/openai/LICENSE

databricks/sdk/__init__.py

@@ -0,0 +1,52 @@
+from databricks.sdk.service.serving import ServingEndpointsAPI
+
+
+class ServingEndpointsExt(ServingEndpointsAPI):
+
+    # Using the HTTP Client to pass in the databricks authorization
+    # This method will be called on every invocation, so when using with model serving will always get the refreshed token
+    def _get_authorized_http_client(self):
+        import httpx
+
+        class BearerAuth(httpx.Auth):
+
+            def __init__(self, get_headers_func):
+                self.get_headers_func = get_headers_func
+
+            def auth_flow(self, request: httpx.Request) -> httpx.Request:
+                auth_headers = self.get_headers_func()
+                request.headers["Authorization"] = auth_headers["Authorization"]
+                yield request
+
+        databricks_token_auth = BearerAuth(self._api._cfg.authenticate)
+
+        # Create an HTTP client with Bearer Token authentication
+        http_client = httpx.Client(auth=databricks_token_auth)
+        return http_client
+
+    def get_open_ai_client(self):
+        try:
+            from openai import OpenAI
+        except Exception:
+            raise ImportError(
+                "Open AI is not installed. Please install the Databricks SDK with the following command `pip isntall databricks-sdk[openai]`"
+            )
+
+        return OpenAI(
+            base_url=self._api._cfg.host + "/serving-endpoints",
+            api_key="no-token", # Passing in a placeholder to pass validations, this will not be used
+            http_client=self._get_authorized_http_client())
+
+    def get_langchain_chat_open_ai_client(self, model):
+        try:
+            from langchain_openai import ChatOpenAI
+        except Exception:
+            raise ImportError(
+                "Langchain Open AI is not installed. Please install the Databricks SDK with the following command `pip isntall databricks-sdk[openai]` and ensure you are using python>3.7"
+            )
+
+        return ChatOpenAI(
+            model=model,
+            openai_api_base=self._api._cfg.host + "/serving-endpoints",
+            api_key="no-token", # Passing in a placeholder to pass validations, this will not be used
+            http_client=self._get_authorized_http_client())

databricks/sdk/mixins/open_ai_client.py

@@ -17,8 +17,10 @@
       extras_require={"dev": ["pytest", "pytest-cov", "pytest-xdist", "pytest-mock",
                               "yapf", "pycodestyle", "autoflake", "isort", "wheel",
                               "ipython", "ipywidgets", "requests-mock", "pyfakefs",
-                              "databricks-connect", "pytest-rerunfailures"],
-                      "notebook": ["ipython>=8,<9", "ipywidgets>=8,<9"]},
+                              "databricks-connect", "pytest-rerunfailures", "openai", 
+                              'langchain-openai; python_version > "3.7"', "httpx"],
+                      "notebook": ["ipython>=8,<9", "ipywidgets>=8,<9"],
+                      "openai": ["openai", 'langchain-openai; python_version > "3.7"', "httpx"]},
       author="Serge Smertin",
       author_email="[email protected]",
       description="Databricks SDK for Python (Beta)",

setup.py

@@ -0,0 +1,30 @@
+import sys
+
+import pytest
+
+from databricks.sdk.core import Config
+
+
+def test_open_ai_client(monkeypatch):
+    from databricks.sdk import WorkspaceClient
+
+    monkeypatch.setenv('DATABRICKS_HOST', 'test_host')
+    monkeypatch.setenv('DATABRICKS_TOKEN', 'test_token')
+    w = WorkspaceClient(config=Config())
+    client = w.serving_endpoints.get_open_ai_client()
+
+    assert client.base_url == "https://test_host/serving-endpoints/"
+    assert client.api_key == "no-token"
+
+
+@pytest.mark.skipif(sys.version_info < (3, 8), reason="Requires Python > 3.7")
+def test_langchain_open_ai_client(monkeypatch):
+    from databricks.sdk import WorkspaceClient
+
+    monkeypatch.setenv('DATABRICKS_HOST', 'test_host')
+    monkeypatch.setenv('DATABRICKS_TOKEN', 'test_token')
+    w = WorkspaceClient(config=Config())
+    client = w.serving_endpoints.get_langchain_chat_open_ai_client("databricks-meta-llama-3-1-70b-instruct")
+
+    assert client.openai_api_base == "https://test_host/serving-endpoints"
+    assert client.model_name == "databricks-meta-llama-3-1-70b-instruct"